Refactor MediumEnvironment to improve FakeClock usage.

PiperOrigin-RevId: 904891357

connections/implementation/analytics/analytics_recorder_test.cc

@@ -151,10 +151,6 @@ class AnalyticsRecorderTest : public ::testing::Test {
   }
 
   void TearDown() override { MediumEnvironment::Instance().Stop(); }
-
-  FakeClock& GetFakeClock() const {
-    return *MediumEnvironment::Instance().GetSimulatedClock().value();
-  }
 };
 
 // Test if session_was_logged_ is reset by checking if LogSession can take
@@ -190,19 +186,19 @@ TEST_F(AnalyticsRecorderTest, SetFieldsCorrectlyForNestedAdvertisingCalls) {
       analytics_recorder.BuildAdvertisingMetadataParams();
   advertising_metadata_params->operation_result_with_mediums = {
       operation_result};
-  GetFakeClock().FastForward(absl::Milliseconds(50));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(50));
   analytics_recorder.OnStartAdvertising(strategy, /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStopAdvertising();
   operation_result.set_medium(BLE);
   advertising_metadata_params->operation_result_with_mediums = {
       operation_result};
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnStartAdvertising(strategy, /*mediums=*/{BLUETOOTH},
                                         advertising_metadata_params.get());
 
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
 
@@ -273,16 +269,16 @@ TEST_F(AnalyticsRecorderTest, SetFieldsCorrectlyForNestedDiscoveryCalls) {
           /*is_extended_advertisement_supported*/ true,
           /*connected_ap_frequency*/ 1, /*is_nfc_available=*/false,
           {operation_result, operation_result2});
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartDiscovery(strategy, /*mediums=*/{BLE, BLUETOOTH},
                                       discovery_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnStopDiscovery();
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnEndpointFound(BLUETOOTH);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnEndpointFound(BLE);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
 
   auto discovery_metadata_params2 =
       analytics_recorder.BuildDiscoveryMetadataParams(
@@ -291,7 +287,7 @@ TEST_F(AnalyticsRecorderTest, SetFieldsCorrectlyForNestedDiscoveryCalls) {
           {operation_result});
   analytics_recorder.OnStartDiscovery(strategy, /*mediums=*/{BLUETOOTH},
                                       discovery_metadata_params2.get());
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -307,14 +303,8 @@ TEST_F(AnalyticsRecorderTest, SetFieldsCorrectlyForNestedDiscoveryCalls) {
             duration_millis: 200
             medium: BLE
             medium: BLUETOOTH
-            discovered_endpoint {
-              medium: BLUETOOTH
-              latency_millis: 500
-            }
-            discovered_endpoint {
-              medium: BLE
-              latency_millis: 900
-            }
+            discovered_endpoint { medium: BLUETOOTH latency_millis: 500 }
+            discovered_endpoint { medium: BLE latency_millis: 900 }
             discovery_metadata {
               supports_extended_ble_advertisements: true
               connected_ap_frequency: 1
@@ -364,38 +354,38 @@ TEST_F(AnalyticsRecorderTest,
 
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(strategy, mediums,
                                         advertising_metadata_params.get());
   auto discovery_metadata_params =
       analytics_recorder.BuildDiscoveryMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnStartDiscovery(strategy, mediums,
                                       discovery_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnStopAdvertising();
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnStopDiscovery();
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.OnStartAdvertising(strategy, mediums,
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.OnStopAdvertising();
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
   analytics_recorder.OnStartDiscovery(strategy, mediums,
                                       discovery_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(800));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(800));
   analytics_recorder.OnStopDiscovery();
-  GetFakeClock().FastForward(absl::Milliseconds(900));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(900));
   analytics_recorder.OnStartDiscovery(strategy, mediums, {});
-  GetFakeClock().FastForward(absl::Milliseconds(1000));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1000));
   analytics_recorder.OnStartAdvertising(strategy, mediums,
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(1100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1100));
   analytics_recorder.OnStopDiscovery();
-  GetFakeClock().FastForward(absl::Milliseconds(1200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1200));
   analytics_recorder.OnStopAdvertising();
-  GetFakeClock().FastForward(absl::Milliseconds(1300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1300));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -503,35 +493,35 @@ TEST_F(AnalyticsRecorderTest, AdvertiserConnectionRequestsWorks) {
       analytics_recorder.BuildAdvertisingMetadataParams();
   advertising_metadata_params->operation_result_with_mediums = {
       operation_result};
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnConnectionRequestReceived(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnLocalEndpointAccepted(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnRemoteEndpointAccepted(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.OnConnectionRequestReceived(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.OnLocalEndpointAccepted(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
   analytics_recorder.OnRemoteEndpointRejected(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(800));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(800));
   analytics_recorder.OnConnectionRequestReceived(endpoint_id_2);
-  GetFakeClock().FastForward(absl::Milliseconds(900));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(900));
   analytics_recorder.OnLocalEndpointRejected(endpoint_id_2);
-  GetFakeClock().FastForward(absl::Milliseconds(1000));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1000));
   analytics_recorder.OnRemoteEndpointAccepted(endpoint_id_2);
-  GetFakeClock().FastForward(absl::Milliseconds(1100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1100));
   analytics_recorder.OnConnectionRequestReceived(endpoint_id_3);
-  GetFakeClock().FastForward(absl::Milliseconds(1200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1200));
   analytics_recorder.OnLocalEndpointRejected(endpoint_id_3);
-  GetFakeClock().FastForward(absl::Milliseconds(1300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1300));
   analytics_recorder.OnRemoteEndpointRejected(endpoint_id_3);
-  GetFakeClock().FastForward(absl::Milliseconds(1400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1400));
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
 
@@ -606,36 +596,36 @@ TEST_F(AnalyticsRecorderTest, DiscoveryConnectionRequestsWorks) {
   auto discovery_metadata_params =
       analytics_recorder.BuildDiscoveryMetadataParams();
   discovery_metadata_params->operation_result_with_mediums = {operation_result};
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartDiscovery(connections::Strategy::kP2pStar,
                                       /*mediums=*/{BLE, BLUETOOTH},
                                       discovery_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnConnectionRequestSent(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnLocalEndpointAccepted(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnRemoteEndpointAccepted(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.OnConnectionRequestSent(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.OnLocalEndpointAccepted(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
   analytics_recorder.OnRemoteEndpointRejected(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(800));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(800));
   analytics_recorder.OnConnectionRequestSent(endpoint_id_2);
-  GetFakeClock().FastForward(absl::Milliseconds(900));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(900));
   analytics_recorder.OnLocalEndpointRejected(endpoint_id_2);
-  GetFakeClock().FastForward(absl::Milliseconds(1000));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1000));
   analytics_recorder.OnRemoteEndpointAccepted(endpoint_id_2);
-  GetFakeClock().FastForward(absl::Milliseconds(1100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1100));
 
   analytics_recorder.OnConnectionRequestSent(endpoint_id_3);
-  GetFakeClock().FastForward(absl::Milliseconds(1200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1200));
   analytics_recorder.OnLocalEndpointRejected(endpoint_id_3);
-  GetFakeClock().FastForward(absl::Milliseconds(1300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1300));
   analytics_recorder.OnRemoteEndpointRejected(endpoint_id_3);
-  GetFakeClock().FastForward(absl::Milliseconds(1400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1400));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -712,26 +702,26 @@ TEST_F(AnalyticsRecorderTest,
       analytics_recorder.BuildAdvertisingMetadataParams();
   advertising_metadata_params->operation_result_with_mediums = {
       operation_result};
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
   // Ignored by local.
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnConnectionRequestReceived(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnRemoteEndpointAccepted(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
 
   // Ignored by remote.
   analytics_recorder.OnConnectionRequestReceived(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.OnLocalEndpointAccepted(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
 
   // Ignored by both.
   analytics_recorder.OnConnectionRequestReceived(endpoint_id_2);
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -801,27 +791,27 @@ TEST_F(AnalyticsRecorderTest,
   auto discovery_metadata_params =
       analytics_recorder.BuildDiscoveryMetadataParams();
   discovery_metadata_params->operation_result_with_mediums = {operation_result};
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartDiscovery(connections::Strategy::kP2pStar,
                                       /*mediums=*/{BLE, BLUETOOTH},
                                       discovery_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
 
   // Ignored by local.
   analytics_recorder.OnConnectionRequestSent(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnRemoteEndpointAccepted(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
 
   // Ignored by remote.
   analytics_recorder.OnConnectionRequestSent(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.OnLocalEndpointAccepted(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
 
   // Ignored by both.
   analytics_recorder.OnConnectionRequestSent(endpoint_id_2);
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -887,7 +877,7 @@ TEST_F(AnalyticsRecorderTest, SuccessfulIncomingConnectionAttempt) {
       analytics_recorder.BuildAdvertisingMetadataParams();
   advertising_metadata_params->operation_result_with_mediums = {
       operation_result};
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
@@ -896,13 +886,13 @@ TEST_F(AnalyticsRecorderTest, SuccessfulIncomingConnectionAttempt) {
       std::make_unique<ConnectionAttemptMetadataParams>();
   connections_attempt_metadata_params->operation_result_code =
       OperationResultCode::DETAIL_SUCCESS;
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnIncomingConnectionAttempt(
       INITIAL, BLUETOOTH, RESULT_SUCCESS, absl::Duration{},
       /*connection_token=*/"", connections_attempt_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnStopAdvertising();
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -982,17 +972,17 @@ TEST_F(AnalyticsRecorderTest,
           OperationResultCode::CONNECTIVITY_BT_CLIENT_SOCKET_CREATION_FAILURE);
   auto discovery_metadata_params =
       analytics_recorder.BuildDiscoveryMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartDiscovery(connections::Strategy::kP2pStar,
                                       /*mediums=*/{BLE, BLUETOOTH},
                                       discovery_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnConnectionRequestSent(endpoint_id);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnOutgoingConnectionAttempt(
       endpoint_id, INITIAL, BLUETOOTH, RESULT_ERROR, absl::Duration{},
       /*connection_token=*/"", connections_attempt_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1063,21 +1053,21 @@ TEST_F(AnalyticsRecorderTest,
 
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnConnectionEstablished(endpoint_id, BLUETOOTH,
                                              connection_token);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnConnectionClosed(
       endpoint_id, BLUETOOTH, UPGRADED,
       ConnectionsLog::EstablishedConnection::UNKNOWN_SAFE_DISCONNECTION_RESULT);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnConnectionEstablished(endpoint_id, WIFI_LAN,
                                              connection_token);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1139,41 +1129,41 @@ TEST_F(AnalyticsRecorderTest, OutgoingPayloadUpgraded) {
 
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnConnectionEstablished(endpoint_id, BLUETOOTH,
                                              connection_token);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnOutgoingPayloadStarted(
       {endpoint_id}, payload_id, connections::PayloadType::kFile, 50);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnPayloadChunkSent(endpoint_id, payload_id, 10);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.OnPayloadChunkSent(endpoint_id, payload_id, 10);
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.OnConnectionClosed(
       endpoint_id, BLUETOOTH, UPGRADED,
       ConnectionsLog::EstablishedConnection::SAFE_DISCONNECTION);
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
   analytics_recorder.OnConnectionEstablished(endpoint_id, WIFI_LAN,
                                              connection_token);
-  GetFakeClock().FastForward(absl::Milliseconds(800));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(800));
   analytics_recorder.OnPayloadChunkSent(endpoint_id, payload_id, 10);
-  GetFakeClock().FastForward(absl::Milliseconds(900));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(900));
   analytics_recorder.OnPayloadChunkSent(endpoint_id, payload_id, 10);
-  GetFakeClock().FastForward(absl::Milliseconds(1000));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1000));
   analytics_recorder.OnPayloadChunkSent(endpoint_id, payload_id, 10);
-  GetFakeClock().FastForward(absl::Milliseconds(1100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1100));
   analytics_recorder.OnOutgoingPayloadDone(endpoint_id, payload_id, SUCCESS,
                                            OperationResultCode::DETAIL_SUCCESS);
-  GetFakeClock().FastForward(absl::Milliseconds(1200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1200));
   analytics_recorder.OnConnectionClosed(
       endpoint_id, WIFI_LAN, LOCAL_DISCONNECTION,
       ConnectionsLog::EstablishedConnection::SAFE_DISCONNECTION);
-  GetFakeClock().FastForward(absl::Milliseconds(1300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1300));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1260,31 +1250,31 @@ TEST_F(AnalyticsRecorderTest, UpgradeAttemptWorks) {
 
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
 
   analytics_recorder.OnBandwidthUpgradeStarted(endpoint_id, BLE, WIFI_LAN,
                                                INCOMING, connection_token);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
 
   analytics_recorder.OnBandwidthUpgradeStarted(
       endpoint_id_1, BLUETOOTH, WIFI_LAN, INCOMING, connection_token);
   // Error to upgrade.
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnBandwidthUpgradeError(
       endpoint_id, WIFI_LAN_MEDIUM_ERROR, WIFI_LAN_SOCKET_CREATION,
       OperationResultCode::CONNECTIVITY_WIFI_LAN_INVALID_CREDENTIAL);
   // Success to upgrade.
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.OnBandwidthUpgradeSuccess(endpoint_id_1);
   // Upgrade is unfinished.
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.OnBandwidthUpgradeStarted(
       endpoint_id_2, BLUETOOTH, WIFI_LAN, INCOMING, connection_token);
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1362,26 +1352,26 @@ TEST_F(AnalyticsRecorderTest, StartListeningForIncomingConnectionsWorks) {
   FakeEventLogger event_logger(client_session_done_latch);
   AnalyticsRecorder analytics_recorder(&event_logger);
 
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartedIncomingConnectionListening(
       connections::Strategy::kP2pStar);
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
 
   analytics_recorder.OnBandwidthUpgradeStarted(endpoint_id, BLE, WIFI_LAN,
                                                INCOMING, connection_token);
 
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnBandwidthUpgradeStarted(
       endpoint_id_1, BLUETOOTH, WIFI_LAN, INCOMING, connection_token);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   // Error to upgrade.
   analytics_recorder.OnBandwidthUpgradeError(
       endpoint_id, WIFI_LAN_MEDIUM_ERROR, WIFI_LAN_SOCKET_CREATION,
       OperationResultCode::CONNECTIVITY_WIFI_LAN_INVALID_CREDENTIAL);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   // Success to upgrade.
   analytics_recorder.OnBandwidthUpgradeSuccess(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
 
   analytics_recorder.LogSession();
   // ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1432,7 +1422,7 @@ TEST_F(AnalyticsRecorderTest, SetErrorCodeFieldsCorrectly) {
 
   auto discovery_metadata_params =
       analytics_recorder.BuildDiscoveryMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartDiscovery(connections::Strategy::kP2pStar,
                                       /*mediums=*/{WEB_RTC},
                                       discovery_metadata_params.get());
@@ -1440,9 +1430,9 @@ TEST_F(AnalyticsRecorderTest, SetErrorCodeFieldsCorrectly) {
   ErrorCodeParams error_code_params = ErrorCodeRecorder::BuildErrorCodeParams(
       WEB_RTC, DISCONNECT, DISCONNECT_NETWORK_FAILED,
       TACHYON_SEND_MESSAGE_STATUS_EXCEPTION, "", "connection_token");
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnErrorCode(error_code_params);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1466,7 +1456,7 @@ TEST_F(AnalyticsRecorderTest,
 
   auto discovery_metadata_params =
       analytics_recorder.BuildDiscoveryMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartDiscovery(connections::Strategy::kP2pStar,
                                       /*mediums=*/{BLUETOOTH},
                                       discovery_metadata_params.get());
@@ -1477,9 +1467,9 @@ TEST_F(AnalyticsRecorderTest,
   error_code_params.event = START_DISCOVERING;
   error_code_params.start_discovering_error = START_EXTENDED_DISCOVERING_FAILED;
   error_code_params.connection_token = "connection_token";
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnErrorCode(error_code_params);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1502,7 +1492,7 @@ TEST_F(AnalyticsRecorderTest, SetErrorCodeFieldsCorrectlyForCommonError) {
 
   auto discovery_metadata_params =
       analytics_recorder.BuildDiscoveryMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartDiscovery(connections::Strategy::kP2pStar,
                                       /*mediums=*/{BLUETOOTH},
                                       discovery_metadata_params.get());
@@ -1510,9 +1500,9 @@ TEST_F(AnalyticsRecorderTest, SetErrorCodeFieldsCorrectlyForCommonError) {
   ErrorCodeParams error_code_params = ErrorCodeRecorder::BuildErrorCodeParams(
       BLUETOOTH, START_DISCOVERING, INVALID_PARAMETER,
       NULL_BLUETOOTH_DEVICE_NAME, "", "connection_token");
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnErrorCode(error_code_params);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1533,7 +1523,7 @@ TEST_F(AnalyticsRecorderTest, CheckIfSessionWasLogged) {
   FakeEventLogger event_logger(client_session_done_latch);
   AnalyticsRecorder analytics_recorder(&event_logger);
 
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   // LogSession to count down client_session_done_latch.
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1635,17 +1625,17 @@ TEST_F(AnalyticsRecorderTest,
 
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnConnectionRequestReceived(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnLocalEndpointAccepted(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnRemoteEndpointAccepted(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
 
   // LogSession
   analytics_recorder.LogSession();  // call ResetClientSessionLoggingResouces
@@ -1684,7 +1674,7 @@ TEST_F(AnalyticsRecorderTest,
   CountDownLatch new_start_client_session_done_latch(1);
   event_logger.SetStartClientSessionDoneLatchPtr(
       &new_start_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.LogStartSession();
   ASSERT_TRUE(
       new_start_client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1693,13 +1683,13 @@ TEST_F(AnalyticsRecorderTest,
   CountDownLatch new_client_session_done_latch(1);
   event_logger.SetClientSessionDoneLatch(new_client_session_done_latch);
   std::string endpoint_id_1 = "endpoint_id_1";
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
   analytics_recorder.OnConnectionRequestReceived(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(800));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(800));
   analytics_recorder.OnLocalEndpointAccepted(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(900));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(900));
   analytics_recorder.OnRemoteEndpointAccepted(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(1000));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1000));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(new_client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1767,18 +1757,18 @@ TEST_F(AnalyticsRecorderTest,
 
   auto discovery_metadata_params =
       analytics_recorder.BuildDiscoveryMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartDiscovery(connections::Strategy::kP2pStar,
                                       /*mediums=*/{BLE, BLUETOOTH},
                                       discovery_metadata_params.get());
 
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnConnectionRequestSent(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnLocalEndpointAccepted(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnRemoteEndpointAccepted(endpoint_id_0);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
 
   // LogSession
   analytics_recorder.LogSession();  // call ResetClientSessionLoggingResouces
@@ -1825,13 +1815,13 @@ TEST_F(AnalyticsRecorderTest,
   CountDownLatch new_client_session_done_latch(1);
   event_logger.SetClientSessionDoneLatch(new_client_session_done_latch);
   std::string endpoint_id_1 = "endpoint_id_1";
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.OnConnectionRequestSent(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
   analytics_recorder.OnLocalEndpointAccepted(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(800));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(800));
   analytics_recorder.OnRemoteEndpointAccepted(endpoint_id_1);
-  GetFakeClock().FastForward(absl::Milliseconds(900));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(900));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1901,14 +1891,14 @@ TEST_F(AnalyticsRecorderTest, ClearcActiveConnectionsAfterSessionWasLogged) {
 
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(strategy, mediums,
                                         advertising_metadata_params.get());
 
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnConnectionEstablished(endpoint_id, BLUETOOTH,
                                              connection_token);
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
 
   // LogSession
   analytics_recorder.LogSession();  // call ResetClientSessionLoggingResouces
@@ -1951,7 +1941,7 @@ TEST_F(AnalyticsRecorderTest, ClearcActiveConnectionsAfterSessionWasLogged) {
   CountDownLatch new_start_client_session_done_latch(1);
   event_logger.SetStartClientSessionDoneLatchPtr(
       &new_start_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.LogStartSession();
   ASSERT_TRUE(
       new_start_client_session_done_latch.Await(kDefaultTimeout).result());
@@ -1959,7 +1949,7 @@ TEST_F(AnalyticsRecorderTest, ClearcActiveConnectionsAfterSessionWasLogged) {
   // LogSession again
   CountDownLatch new_client_session_done_latch(1);
   event_logger.SetClientSessionDoneLatch(new_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
 
@@ -2024,33 +2014,33 @@ TEST_F(AnalyticsRecorderTest,
 
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
 
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnBandwidthUpgradeStarted(endpoint_id, BLE, WIFI_LAN,
                                                INCOMING, connection_token);
 
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnBandwidthUpgradeStarted(
       endpoint_id_1, BLUETOOTH, WIFI_LAN, INCOMING, connection_token);
   // - Error to upgrade.
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnBandwidthUpgradeError(
       endpoint_id, WIFI_LAN_MEDIUM_ERROR, WIFI_LAN_SOCKET_CREATION,
       OperationResultCode::CONNECTIVITY_WIFI_LAN_INVALID_CREDENTIAL);
   // - Success to upgrade.
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.OnBandwidthUpgradeSuccess(endpoint_id_1);
 
   // - Upgrade is unfinished.
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.OnBandwidthUpgradeStarted(
       endpoint_id_2, BLUETOOTH, WIFI_LAN, INCOMING, connection_token);
 
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
   // LogSession
   analytics_recorder.LogSession();  // call ResetClientSessionLoggingResouces
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -2123,7 +2113,7 @@ TEST_F(AnalyticsRecorderTest,
   CountDownLatch new_start_client_session_done_latch(1);
   event_logger.SetStartClientSessionDoneLatchPtr(
       &new_start_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(800));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(800));
   analytics_recorder.LogStartSession();
   ASSERT_TRUE(
       new_start_client_session_done_latch.Await(kDefaultTimeout).result());
@@ -2131,7 +2121,7 @@ TEST_F(AnalyticsRecorderTest,
   // LogSession again
   CountDownLatch new_client_session_done_latch(1);
   event_logger.SetClientSessionDoneLatch(new_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(900));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(900));
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
 
@@ -2216,14 +2206,14 @@ TEST_F(AnalyticsRecorderTest,
 
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLUETOOTH},
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnStopAdvertising();
 
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   // LogSession
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -2237,7 +2227,7 @@ TEST_F(AnalyticsRecorderTest,
   CountDownLatch new_start_client_session_done_latch(1);
   event_logger.SetStartClientSessionDoneLatchPtr(
       &new_start_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.LogStartSession();
   ASSERT_TRUE(
       new_start_client_session_done_latch.Await(kDefaultTimeout).result());
@@ -2246,12 +2236,12 @@ TEST_F(AnalyticsRecorderTest,
   CountDownLatch new_client_session_done_latch(1);
   event_logger.SetClientSessionDoneLatch(new_client_session_done_latch);
 
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.OnStartAdvertising(strategy, /*mediums=*/{BLUETOOTH},
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.OnStopAdvertising();
-  GetFakeClock().FastForward(absl::Milliseconds(700));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(700));
 
   analytics_recorder.LogSession();
   ASSERT_TRUE(new_client_session_done_latch.Await(kDefaultTimeout).result());
@@ -2272,13 +2262,13 @@ TEST_F(AnalyticsRecorderTest,
   // UpdateStrategySessionLocked.
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnStopAdvertising();
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   // LogSession
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -2310,7 +2300,7 @@ TEST_F(AnalyticsRecorderTest,
   CountDownLatch new_start_client_session_done_latch(1);
   event_logger.SetStartClientSessionDoneLatchPtr(
       &new_start_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.LogStartSession();
   ASSERT_TRUE(
       new_start_client_session_done_latch.Await(kDefaultTimeout).result());
@@ -2320,7 +2310,7 @@ TEST_F(AnalyticsRecorderTest,
   // strategy_session_proto will be logged.
   CountDownLatch new_client_session_done_latch(1);
   event_logger.SetClientSessionDoneLatch(new_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.LogSession();
   ASSERT_TRUE(new_client_session_done_latch.Await(kDefaultTimeout).result());
 
@@ -2337,14 +2327,14 @@ TEST_F(AnalyticsRecorderTest,
 
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(
       connections::Strategy::kP2pStar,
       /*mediums=*/{BLUETOOTH},
       advertising_metadata_params.get());  // set current_advertising_phase_
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnStopAdvertising();
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
 
   // LogSession
   analytics_recorder.LogSession();
@@ -2376,7 +2366,7 @@ TEST_F(AnalyticsRecorderTest,
   CountDownLatch new_start_client_session_done_latch(1);
   event_logger.SetStartClientSessionDoneLatchPtr(
       &new_start_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.LogStartSession();
   ASSERT_TRUE(
       new_start_client_session_done_latch.Await(kDefaultTimeout).result());
@@ -2387,7 +2377,7 @@ TEST_F(AnalyticsRecorderTest,
   // be logged.
   CountDownLatch new_client_session_done_latch(1);
   event_logger.SetClientSessionDoneLatch(new_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
 
@@ -2434,15 +2424,15 @@ TEST_F(AnalyticsRecorderTest,
       analytics_recorder.BuildDiscoveryMetadataParams(
           /*is_extended_advertisement_supported*/ true,
           /*connected_ap_frequency*/ 1, /*is_nfc_available=*/false);
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartDiscovery(
       strategy, {BLUETOOTH},
       discovery_metadata_params.get());  // set current_discovery_phase_
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnStopDiscovery();
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
   analytics_recorder.OnEndpointFound(BLUETOOTH);
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   // LogSession
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
@@ -2457,10 +2447,7 @@ TEST_F(AnalyticsRecorderTest,
           discovery_phase {
             duration_millis: 200
             medium: BLUETOOTH
-            discovered_endpoint {
-              medium: BLUETOOTH
-              latency_millis: 500
-            }
+            discovered_endpoint { medium: BLUETOOTH latency_millis: 500 }
             discovery_metadata {
               supports_extended_ble_advertisements: true
               connected_ap_frequency: 1
@@ -2477,7 +2464,7 @@ TEST_F(AnalyticsRecorderTest,
   CountDownLatch new_start_client_session_done_latch(1);
   event_logger.SetStartClientSessionDoneLatchPtr(
       &new_start_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.LogStartSession();
   ASSERT_TRUE(
       new_start_client_session_done_latch.Await(kDefaultTimeout).result());
@@ -2488,7 +2475,7 @@ TEST_F(AnalyticsRecorderTest,
   // logged.
   CountDownLatch new_client_session_done_latch(1);
   event_logger.SetClientSessionDoneLatch(new_client_session_done_latch);
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.LogSession();
   ASSERT_TRUE(client_session_done_latch.Await(kDefaultTimeout).result());
 
@@ -2536,13 +2523,13 @@ TEST_F(AnalyticsRecorderTest,
   // UpdateStrategySessionLocked.
   auto advertising_metadata_params =
       analytics_recorder.BuildAdvertisingMetadataParams();
-  GetFakeClock().FastForward(absl::Milliseconds(100));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(100));
   analytics_recorder.OnStartAdvertising(connections::Strategy::kP2pStar,
                                         /*mediums=*/{BLE, BLUETOOTH},
                                         advertising_metadata_params.get());
-  GetFakeClock().FastForward(absl::Milliseconds(200));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(200));
   analytics_recorder.OnStopAdvertising();
-  GetFakeClock().FastForward(absl::Milliseconds(300));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(300));
 
   // LogSession
   analytics_recorder.LogSession();
@@ -2573,14 +2560,14 @@ TEST_F(AnalyticsRecorderTest,
 
   // Without calling OnStartAdvertising won't create new
   // current_strategy_session_.
-  GetFakeClock().FastForward(absl::Milliseconds(400));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(400));
   analytics_recorder.OnConnectionEstablished(endpoint_id, BLUETOOTH,
                                              /*connection_token=*/"");
-  GetFakeClock().FastForward(absl::Milliseconds(500));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(500));
   analytics_recorder.OnConnectionClosed(
       endpoint_id, BLUETOOTH, UPGRADED,
       ConnectionsLog::EstablishedConnection::SAFE_DISCONNECTION);
-  GetFakeClock().FastForward(absl::Milliseconds(600));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(600));
   analytics_recorder.LogSession();
 
   // The proto won't change.

connections/implementation/client_proxy_test.cc

@@ -360,10 +360,7 @@ class ClientProxyTest : public ::testing::TestWithParam<FeatureFlags::Flags> {
   ClientProxy* client2() { return client2_.get(); }
 
   void FastForward(absl::Duration duration) {
-    (*env_.GetSimulatedClock())
-        ->FastForward(
-            ClientProxy::kHighPowerAdvertisementEndpointIdCacheTimeout +
-            absl::Milliseconds(100));
+    env_.FastForward(duration);
     // make sure the timer based callback is executed.
     absl::SleepFor(absl::Milliseconds(100));
   }

connections/implementation/mediums/ble/discovered_peripheral_tracker_test.cc

@@ -17,7 +17,6 @@
 #include <atomic>
 #include <list>
 #include <memory>
-#include <optional>
 #include <string>
 #include <tuple>
 #include <utility>
@@ -53,7 +52,6 @@
 #include "internal/platform/mutex.h"
 #include "internal/platform/mutex_lock.h"
 #include "internal/platform/uuid.h"
-#include "internal/test/fake_clock.h"
 
 namespace nearby {
 namespace connections {
@@ -1628,9 +1626,6 @@ TEST_P(DiscoveredPeripheralTrackerTest,
 
 TEST_P(DiscoveredPeripheralTrackerTest,
        OnlyGattAdvertisementReceivedOnDeviceWithExtended) {
-  std::optional<FakeClock*> fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock();
-
   std::vector<std::string> service_ids = {std::string(kServiceIdA)};
   ByteArray advertisement_hash = GenerateRandomAdvertisementHash();
   ByteArray advertisement_header_bytes =
@@ -1668,7 +1663,7 @@ TEST_P(DiscoveredPeripheralTrackerTest,
 
   // 2. Receive GATT advertisement data again after 4 seconds, it should access
   // GATT server.
-  (*fake_clock)->FastForward(absl::Seconds(4));
+  MediumEnvironment::Instance().FastForward(absl::Seconds(4));
   FindAdvertisement(advertisement_data, {advertisement_bytes}, fetch_latch);
 
   // We should receive a client callback of a peripheral discovery.
@@ -1678,9 +1673,6 @@ TEST_P(DiscoveredPeripheralTrackerTest,
 }
 
 TEST_P(DiscoveredPeripheralTrackerTest, SkipExpiredGattAdvertisement) {
-  std::optional<FakeClock*> fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock();
-
   std::vector<std::string> service_ids = {std::string(kServiceIdA)};
   ByteArray advertisement_hash = GenerateRandomAdvertisementHash();
   ByteArray advertisement_header_bytes =
@@ -1718,7 +1710,7 @@ TEST_P(DiscoveredPeripheralTrackerTest, SkipExpiredGattAdvertisement) {
 
   // 2. The GATT advertisement is already queued and will be skipped.
   FindAdvertisement(advertisement_data, {advertisement_bytes}, fetch_latch);
-  (*fake_clock)->FastForward(absl::Seconds(20));
+  MediumEnvironment::Instance().FastForward(absl::Seconds(20));
   discovered_peripheral_tracker_->StartFetchExecutorForTesting();
 
   // We should not receive a client callback of a peripheral discovery.
@@ -1729,9 +1721,6 @@ TEST_P(DiscoveredPeripheralTrackerTest, SkipExpiredGattAdvertisement) {
 
 TEST_P(DiscoveredPeripheralTrackerTest,
        DiscoveredOnceWhenGattAndExtendedAdvertisementReceived) {
-  std::optional<FakeClock*> fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock();
-
   std::vector<std::string> service_ids = {std::string(kServiceIdA)};
   ByteArray advertisement_hash = GenerateRandomAdvertisementHash();
   ByteArray advertisement_header_bytes =
@@ -1756,7 +1745,7 @@ TEST_P(DiscoveredPeripheralTrackerTest,
               },
       },
       bleutils::kCopresenceServiceUuid);
-  (*fake_clock)->FastForward(absl::Seconds(4));
+  MediumEnvironment::Instance().FastForward(absl::Seconds(4));
   discovered_peripheral_tracker_->StartFetchExecutorForTesting();
 
   // 1. Received extended advertisement.
@@ -1784,8 +1773,6 @@ TEST_P(DiscoveredPeripheralTrackerTest,
 
 TEST_P(DiscoveredPeripheralTrackerTest,
        FindGattAdvertisementInHigherPriorityThanExtendedGattAdvertisement) {
-  std::optional<FakeClock*> fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock();
   std::vector<std::string> service_ids = {std::string(kServiceIdA)};
   ByteArray advertisement_hash_a = GenerateRandomAdvertisementHash();
   ByteArray advertisement_header_a =
@@ -1823,7 +1810,7 @@ TEST_P(DiscoveredPeripheralTrackerTest,
               },
       },
       bleutils::kCopresenceServiceUuid);
-  (*fake_clock)->FastForward(absl::Seconds(4));
+  MediumEnvironment::Instance().FastForward(absl::Seconds(4));
   discovered_peripheral_tracker_->StartFetchExecutorForTesting();
 
   // 1. Find peripheral A with GATT advertisement.

internal/platform/implementation/g3/scheduled_executor.cc

@@ -16,16 +16,15 @@
 
 #include <atomic>
 #include <memory>
-#include <optional>
 #include <utility>
 
 #include "absl/strings/str_format.h"
 #include "absl/synchronization/mutex.h"
 #include "absl/time/time.h"
 #include "internal/platform/implementation/cancelable.h"
+#include "internal/platform/logging.h"
 #include "internal/platform/medium_environment.h"
 #include "internal/platform/runnable.h"
-#include "internal/test/fake_clock.h"
 
 namespace nearby {
 namespace g3 {
@@ -66,20 +65,13 @@ class ScheduledCancelable : public api::Cancelable {
 }  // namespace
 
 ScheduledExecutor::ScheduledExecutor() {
-  std::optional<FakeClock*> fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock();
-  if (fake_clock.has_value()) {
-    name_ = absl::StrFormat("G3 scheduled executor %p", this);
-    (*fake_clock)->AddObserver(name_, [this]() { RunReadyTasks(); });
-  }
+  name_ = absl::StrFormat("G3 scheduled executor %p", this);
+  MediumEnvironment::Instance().AddSimulatedClockObserver(
+      name_, [this]() { RunReadyTasks(); });
 }
 
 ScheduledExecutor::~ScheduledExecutor() {
-  std::optional<FakeClock*> fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock();
-  if (fake_clock.has_value()) {
-    (*fake_clock)->RemoveObserver(name_);
-  }
+  MediumEnvironment::Instance().RemoveSimulatedClockObserver(name_);
   executor_.Shutdown();
 }
 
@@ -96,10 +88,10 @@ std::shared_ptr<api::Cancelable> ScheduledExecutor::Schedule(
       runnable();
     }
   };
-  std::optional<FakeClock*> fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock();
-  if (fake_clock.has_value()) {
-    absl::Time trigger_time = (*fake_clock)->Now() + delay;
+  if (MediumEnvironment::Instance()
+          .GetEnvironmentConfig()
+          .use_simulated_clock) {
+    absl::Time trigger_time = MediumEnvironment::Instance().Now() + delay;
     absl::MutexLock lock(mutex_);
     tasks_.insert(std::pair<absl::Time, std::unique_ptr<Runnable>>(
         trigger_time, std::make_unique<Runnable>(std::move(task))));
@@ -110,15 +102,12 @@ std::shared_ptr<api::Cancelable> ScheduledExecutor::Schedule(
 }
 
 void ScheduledExecutor::RunReadyTasks() {
-  std::optional<FakeClock*> fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock();
   if (executor_.InShutdown()) {
     return;
   }
-  if (!fake_clock.has_value()) {
-    return;
-  }
-  absl::Time current_time = (*fake_clock)->Now();
+  CHECK(
+      MediumEnvironment::Instance().GetEnvironmentConfig().use_simulated_clock);
+  absl::Time current_time = MediumEnvironment::Instance().Now();
   absl::MutexLock lock(mutex_);
   for (auto it = tasks_.begin(); it != tasks_.end();) {
     if (it->first <= current_time) {

internal/platform/implementation/g3/system_clock.cc

@@ -15,26 +15,21 @@
 #include "internal/platform/implementation/system_clock.h"
 
 #include "absl/time/clock.h"
+#include "absl/time/time.h"
 #include "internal/platform/exception.h"
 #include "internal/platform/medium_environment.h"
-#include "internal/test/fake_clock.h"
 
 namespace nearby {
 
 absl::Time SystemClock::ElapsedRealtime() {
-  absl::optional<FakeClock*> fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock();
-  if (fake_clock.has_value()) {
-    return (*fake_clock)->Now();
-  }
-  return absl::Now();
+  return MediumEnvironment::Instance().Now();
 }
 
 Exception SystemClock::Sleep(absl::Duration duration) {
-  absl::optional<FakeClock*> fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock();
-  if (fake_clock.has_value()) {
-    (*fake_clock)->FastForward(duration);
+  if (MediumEnvironment::Instance()
+          .GetEnvironmentConfig()
+          .use_simulated_clock) {
+    MediumEnvironment::Instance().FastForward(duration);
   } else {
     absl::SleepFor(duration);
   }

internal/platform/medium_environment.cc

@@ -16,6 +16,7 @@
 
 #include <atomic>
 #include <cstdint>
+#include <functional>
 #include <memory>
 #include <optional>
 #include <string>
@@ -27,6 +28,7 @@
 #include "absl/status/status.h"
 #include "absl/strings/str_format.h"
 #include "absl/strings/string_view.h"
+#include "absl/time/clock.h"
 #include "absl/time/time.h"
 #include "internal/platform/borrowable.h"
 #include "internal/platform/byte_array.h"
@@ -46,6 +48,7 @@
 #include "internal/platform/nsd_service_info.h"
 #include "internal/platform/prng.h"
 #include "internal/platform/runnable.h"
+#include "internal/platform/service_address.h"
 #include "internal/platform/uuid.h"
 #include "internal/platform/wifi_credential.h"
 #include "internal/test/fake_clock.h"
@@ -69,10 +72,14 @@ MediumEnvironment& MediumEnvironment::Instance() {
 void MediumEnvironment::Start(EnvironmentConfig config) {
   if (!enabled_.exchange(true)) {
     LOG(INFO) << "MediumEnvironment::Start()";
-    config_ = std::move(config);
-    if (config_.use_simulated_clock) {
+    {
       MutexLock lock(&mutex_);
-      simulated_clock_ = std::make_unique<FakeClock>();
+      config_ = std::move(config);
+      if (config_.use_simulated_clock) {
+        simulated_clock_ = std::make_shared<FakeClock>();
+      } else {
+        simulated_clock_.reset();
+      }
     }
     Reset();
   }
@@ -82,8 +89,8 @@ void MediumEnvironment::Stop() {
   if (enabled_.exchange(false)) {
     LOG(INFO) << "MediumEnvironment::Stop()";
     Sync(false);
+    MutexLock lock(&mutex_);
     if (config_.use_simulated_clock) {
-      MutexLock lock(&mutex_);
       simulated_clock_.reset();
     }
     config_ = {};
@@ -132,7 +139,8 @@ void MediumEnvironment::Sync(bool enable_notifications) {
   LOG(INFO) << "MediumEnvironment::Sync(): done [count=" << count << "]";
 }
 
-const EnvironmentConfig& MediumEnvironment::GetEnvironmentConfig() {
+EnvironmentConfig MediumEnvironment::GetEnvironmentConfig() {
+  MutexLock lock(&mutex_);
   return config_;
 }
 
@@ -1150,12 +1158,43 @@ void MediumEnvironment::SetFeatureFlags(const FeatureFlags::Flags& flags) {
   FeatureFlags::GetMutableInstanceForTesting().SetFlags(flags);
 }
 
-std::optional<FakeClock*> MediumEnvironment::GetSimulatedClock() {
+absl::Time MediumEnvironment::Now() {
   MutexLock lock(&mutex_);
   if (simulated_clock_) {
-    return std::optional<FakeClock*>(simulated_clock_.get());
+    return simulated_clock_->Now();
+  }
+  return absl::Now();
+}
+
+// If simulated_clock_ is valid, it will be advanced by the given duration.
+// If simulated_clock_ is not valid, this method will do nothing.
+void MediumEnvironment::FastForward(absl::Duration duration) {
+  std::shared_ptr<FakeClock> sim_clock;
+  {
+    MutexLock lock(&mutex_);
+    if (simulated_clock_) {
+      sim_clock = simulated_clock_;
+    }
+  }
+  if (sim_clock) {
+    // Mutex is unlocked before calling FastForward to prevent deadlocks.
+    sim_clock->FastForward(duration);
+  }
+}
+
+void MediumEnvironment::AddSimulatedClockObserver(
+    const std::string& name, std::function<void()> observer) {
+  MutexLock lock(&mutex_);
+  if (simulated_clock_) {
+    simulated_clock_->AddObserver(name, std::move(observer));
+  }
+}
+
+void MediumEnvironment::RemoveSimulatedClockObserver(const std::string& name) {
+  MutexLock lock(&mutex_);
+  if (simulated_clock_) {
+    simulated_clock_->RemoveObserver(name);
   }
-  return std::nullopt;
 }
 
 void MediumEnvironment::RegisterGattServer(

internal/platform/medium_environment.h

@@ -17,6 +17,7 @@
 
 #include <atomic>
 #include <cstdint>
+#include <functional>
 #include <memory>
 #include <optional>
 #include <string>
@@ -162,7 +163,7 @@ class MediumEnvironment {
   // Returns a Bluetooth Device object matching given mac address to nullptr.
   api::BluetoothDevice* FindBluetoothDevice(MacAddress mac_address);
 
-  const EnvironmentConfig& GetEnvironmentConfig();
+  EnvironmentConfig GetEnvironmentConfig();
 #ifndef NO_WEBRTC
   // Registers |message_callback| to receive messages sent to device with id
   // |self_id|, and |complete_callback| to notify when signaling is complete.
@@ -334,7 +335,11 @@ class MediumEnvironment {
 
   void SetFeatureFlags(const FeatureFlags::Flags& flags);
 
-  std::optional<FakeClock*> GetSimulatedClock();
+  absl::Time Now();
+  void FastForward(absl::Duration duration);
+  void AddSimulatedClockObserver(const std::string& name,
+                                 std::function<void()> observer);
+  void RemoveSimulatedClockObserver(const std::string& name);
 
   api::ble::BleMedium* FindBleMedium(api::ble::BlePeripheral::UniqueId id);
 
@@ -516,7 +521,7 @@ class MediumEnvironment {
 
   bool use_valid_peer_connection_ = true;
   absl::Duration peer_connection_latency_ = absl::ZeroDuration();
-  std::unique_ptr<FakeClock> simulated_clock_ ABSL_GUARDED_BY(mutex_);
+  std::shared_ptr<FakeClock> simulated_clock_ ABSL_GUARDED_BY(mutex_);
   ObserverList<api::BluetoothClassicMedium::Observer> observers_;
   bool ble_extended_advertisements_available_ = false;
 };

internal/platform/scheduled_executor_test.cc

@@ -25,13 +25,12 @@
 #include "internal/platform/cancelable.h"
 #include "internal/platform/count_down_latch.h"
 #include "internal/platform/medium_environment.h"
-#include "internal/test/fake_clock.h"
 
 namespace nearby {
 
 // kShortDelay must be significant enough to guarantee that OS under heavy load
 // should be able to execute the non-blocking test paths within this time.
-absl::Duration kShortDelay = absl::Milliseconds(100);
+absl::Duration kShortDelay = absl::Milliseconds(200);
 
 // kLongDelay must be long enough to make sure that under OS under heavy load
 // will let kShortDelay fire and jobs scheduled before the kLongDelay fires.
@@ -212,8 +211,6 @@ TEST(ScheduledExecutorTest, ExecuteDuringShutdownFails) {
 
 TEST(ScheduledExecutorTest, SimulatedClockCanSchedule) {
   MediumEnvironment::Instance().Start({.use_simulated_clock = true});
-  FakeClock* fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock().value();
   ScheduledExecutor executor;
   std::atomic_int value = 0;
   CountDownLatch first_task_latch(1);
@@ -235,24 +232,23 @@ TEST(ScheduledExecutorTest, SimulatedClockCanSchedule) {
       },
       kShortDelay);
   EXPECT_EQ(value, 0);
-  fake_clock->FastForward(kShortDelay - absl::Milliseconds(1));
+  MediumEnvironment::Instance().FastForward(kShortDelay -
+                                            absl::Milliseconds(1));
   EXPECT_EQ(value, 0);
-  fake_clock->FastForward(absl::Milliseconds(1));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1));
   second_task_latch.Await();
   EXPECT_EQ(value, 1);
-  fake_clock->FastForward(kLongDelay - kShortDelay);
+  MediumEnvironment::Instance().FastForward(kLongDelay - kShortDelay);
   first_task_latch.Await();
   EXPECT_EQ(value, 5);
   // Very long sleep to make sure that the sleep is truly simulated.
-  fake_clock->FastForward(absl::Minutes(30));
+  MediumEnvironment::Instance().FastForward(absl::Minutes(30));
   MediumEnvironment::Instance().Stop();
 }
 
 TEST(ScheduledExecutorTest,
      DestroyExecutorWithSimulatedClockIgnoresPendingTasks) {
   MediumEnvironment::Instance().Start({.use_simulated_clock = true});
-  FakeClock* fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock().value();
   {
     ScheduledExecutor executor;
     executor.Schedule(
@@ -262,7 +258,7 @@ TEST(ScheduledExecutorTest,
         },
         kShortDelay);
   }
-  fake_clock->FastForward(absl::Minutes(30));
+  MediumEnvironment::Instance().FastForward(absl::Minutes(30));
   MediumEnvironment::Instance().Stop();
 }
 
@@ -403,8 +399,6 @@ TEST(ScheduledExecutorTest, CanCancelOneOfTwoRepeatedTasks) {
 
 TEST(ScheduledExecutorTest, SimulatedClockCanScheduleRepeatedly) {
   MediumEnvironment::Instance().Start({.use_simulated_clock = true});
-  FakeClock* fake_clock =
-      MediumEnvironment::Instance().GetSimulatedClock().value();
   ScheduledExecutor executor;
   std::atomic_int value = 0;
   std::atomic_int i = 0;
@@ -419,11 +413,12 @@ TEST(ScheduledExecutorTest, SimulatedClockCanScheduleRepeatedly) {
 
   EXPECT_EQ(value, 0);
   // Advance to just before the first execution.
-  fake_clock->FastForward(kShortDelay - absl::Milliseconds(1));
+  MediumEnvironment::Instance().FastForward(kShortDelay -
+                                            absl::Milliseconds(1));
   EXPECT_EQ(value, 0);
 
   // Advance past the first execution.
-  fake_clock->FastForward(absl::Milliseconds(1));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1));
   latch[0].Await(absl::Seconds(1));
   EXPECT_EQ(value, 1);
 
@@ -431,11 +426,12 @@ TEST(ScheduledExecutorTest, SimulatedClockCanScheduleRepeatedly) {
   absl::SleepFor(kShortDelay);
 
   // Advance to just before the second execution.
-  fake_clock->FastForward(kShortDelay - absl::Milliseconds(1));
+  MediumEnvironment::Instance().FastForward(kShortDelay -
+                                            absl::Milliseconds(1));
   EXPECT_EQ(value, 1);
 
   // Advance past the second execution.
-  fake_clock->FastForward(absl::Milliseconds(1));
+  MediumEnvironment::Instance().FastForward(absl::Milliseconds(1));
   latch[1].Await(absl::Seconds(1));
   EXPECT_EQ(value, 2);
 
@@ -443,7 +439,7 @@ TEST(ScheduledExecutorTest, SimulatedClockCanScheduleRepeatedly) {
   cancelable.Cancel();
 
   // Advance a long time and make sure it doesn't run again.
-  fake_clock->FastForward(kLongDelay * 5);
+  MediumEnvironment::Instance().FastForward(kLongDelay * 5);
   EXPECT_EQ(value, 2);
 
   MediumEnvironment::Instance().Stop();

internal/test/fake_clock.cc

@@ -19,6 +19,10 @@
 #include <utility>
 #include <vector>
 
+#include "absl/strings/string_view.h"
+#include "absl/synchronization/mutex.h"
+#include "absl/time/time.h"
+
 namespace nearby {
 
 FakeClock::~FakeClock() {

internal/test/fake_clock.h

@@ -53,6 +53,7 @@ class FakeClock : public Clock {
   absl::flat_hash_map<std::string, std::function<void()>> observers_
       ABSL_GUARDED_BY(mutex_);
 };
+
 }  // namespace nearby
 
 #endif  // THIRD_PARTY_NEARBY_INTERNAL_TEST_FAKE_CLOCK_H_

internal/test/fake_clock_test.cc

@@ -14,9 +14,8 @@
 
 #include "internal/test/fake_clock.h"
 
-#include "gmock/gmock.h"
-#include "protobuf-matchers/protocol-buffer-matchers.h"
 #include "gtest/gtest.h"
+#include "absl/time/time.h"
 
 namespace nearby {
 namespace {