From d7a1fb8c48b0f1c5c580c75fedf2d79aab0e8f50 Mon Sep 17 00:00:00 2001
From: Edwin Wu <edwinwu@google.com>
Date: Mon, 9 Dec 2024 00:19:59 -0800
Subject: [PATCH] analytics: Update the returned code for
 CreateUpgradedEndpointChannel of BWUHanlder and its enherited class for NC
 mediums.

PiperOrigin-RevId: 704171725
---
 .../implementation/base_bwu_handler_test.cc   | 22 ++++++++++----
 .../implementation/bluetooth_bwu_handler.cc   | 27 ++++++++++++-----
 .../implementation/bluetooth_bwu_handler.h    | 19 ++++++++----
 .../implementation/bluetooth_bwu_test.cc      | 12 ++++++--
 connections/implementation/bwu_handler.h      | 17 ++++++-----
 connections/implementation/bwu_manager.cc     |  6 ++--
 connections/implementation/fake_bwu_handler.h | 12 ++++++--
 .../implementation/webrtc_bwu_handler.cc      | 13 ++++++--
 .../implementation/webrtc_bwu_handler.h       | 15 ++++++----
 .../implementation/webrtc_bwu_handler_stub.cc |  9 ++++--
 .../implementation/webrtc_bwu_handler_stub.h  | 14 +++++----
 .../implementation/wifi_direct_bwu_handler.cc | 19 +++++++-----
 .../implementation/wifi_direct_bwu_handler.h  | 21 +++++++++----
 .../implementation/wifi_direct_bwu_test.cc    | 21 +++++++++++--
 .../wifi_hotspot_bwu_handler.cc               | 18 ++++++-----
 .../implementation/wifi_hotspot_bwu_handler.h | 22 ++++++++++----
 .../implementation/wifi_hotspot_bwu_test.cc   | 22 ++++++++++++--
 .../implementation/wifi_lan_bwu_handler.cc    | 30 +++++++++++++------
 .../implementation/wifi_lan_bwu_handler.h     | 22 ++++++++++----
 19 files changed, 250 insertions(+), 91 deletions(-)

diff --git a/connections/implementation/base_bwu_handler_test.cc b/connections/implementation/base_bwu_handler_test.cc
index 13fe331b..b87c8d5b 100644
--- a/connections/implementation/base_bwu_handler_test.cc
+++ b/connections/implementation/base_bwu_handler_test.cc
@@ -14,18 +14,27 @@
 
 #include "connections/implementation/base_bwu_handler.h"
 
+#include <memory>
+#include <optional>
 #include <string>
+#include <vector>
 
 #include "gtest/gtest.h"
 #include "absl/strings/string_view.h"
+#include "connections/implementation/client_proxy.h"
+#include "connections/implementation/endpoint_channel.h"
 #include "connections/implementation/service_id_constants.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
 
 namespace nearby {
 namespace connections {
 namespace {
 
-// Because BaseBwuHandler is still an abstract class, we need to implement the
-// pure virtual functions in order to test BaseBwuHandler's bookkeeping logic.
+using ::location::nearby::proto::connections::OperationResultCode;
+
+//  Because BaseBwuHandler is still an abstract class, we need to implement the
+//  pure virtual functions in order to test BaseBwuHandler's bookkeeping logic.
 class BwuHandlerImpl : public BaseBwuHandler {
  public:
   using Medium = ::location::nearby::proto::connections::Medium;
@@ -34,8 +43,8 @@ class BwuHandlerImpl : public BaseBwuHandler {
   // for every method.
   struct InputData {
     ClientProxy* client = nullptr;
-    absl::optional<std::string> service_id;
-    absl::optional<std::string> endpoint_id;
+    std::optional<std::string> service_id;
+    std::optional<std::string> endpoint_id;
   };
 
   BwuHandlerImpl() : BaseBwuHandler(nullptr) {}
@@ -52,11 +61,12 @@ class BwuHandlerImpl : public BaseBwuHandler {
 
  private:
   // BwuHandler implementation:
-  std::unique_ptr<EndpointChannel> CreateUpgradedEndpointChannel(
+  ErrorOr<std::unique_ptr<EndpointChannel>>
+  CreateUpgradedEndpointChannel(
       ClientProxy* client, const std::string& service_id,
       const std::string& endpoint_id,
       const UpgradePathInfo& upgrade_path_info) final {
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
   Medium GetUpgradeMedium() const final { return Medium::UNKNOWN_MEDIUM; }
   void OnEndpointDisconnect(ClientProxy* client,
diff --git a/connections/implementation/bluetooth_bwu_handler.cc b/connections/implementation/bluetooth_bwu_handler.cc
index 74e72312..24a49e53 100644
--- a/connections/implementation/bluetooth_bwu_handler.cc
+++ b/connections/implementation/bluetooth_bwu_handler.cc
@@ -14,13 +14,21 @@
 
 #include "connections/implementation/bluetooth_bwu_handler.h"
 
+#include <memory>
 #include <string>
 #include <utility>
 
 #include "absl/functional/bind_front.h"
+#include "connections/implementation/base_bwu_handler.h"
 #include "connections/implementation/bluetooth_endpoint_channel.h"
 #include "connections/implementation/client_proxy.h"
+#include "connections/implementation/endpoint_channel.h"
+#include "connections/implementation/mediums/mediums.h"
 #include "connections/implementation/offline_frames.h"
+#include "internal/platform/bluetooth_adapter.h"
+#include "internal/platform/bluetooth_classic.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
 #include "internal/platform/logging.h"
 
 // Manages the Bluetooth-specific methods needed to upgrade an {@link
@@ -29,6 +37,11 @@
 namespace nearby {
 namespace connections {
 
+namespace {
+using ::location::nearby::proto::connections::OperationResultCode;
+}  // namespace
+
+// TODO(edwinwu): Add exact OperationResultCode for BluetoothBwuHandler.
 BluetoothBwuHandler::BluetoothBwuHandler(
     Mediums& mediums, IncomingConnectionCallback incoming_connection_callback)
     : BaseBwuHandler(std::move(incoming_connection_callback)),
@@ -37,7 +50,7 @@ BluetoothBwuHandler::BluetoothBwuHandler(
 // Called by BWU target. Retrieves a new medium info from incoming message,
 // and establishes connection over BT using this info.
 // Returns a channel ready to exchange data or nullptr on error.
-std::unique_ptr<EndpointChannel>
+ErrorOr<std::unique_ptr<EndpointChannel>>
 BluetoothBwuHandler::CreateUpgradedEndpointChannel(
     ClientProxy* client, const std::string& service_id,
     const std::string& endpoint_id, const UpgradePathInfo& upgrade_path_info) {
@@ -47,7 +60,7 @@ BluetoothBwuHandler::CreateUpgradedEndpointChannel(
       !bluetooth_credentials.has_mac_address()) {
     NEARBY_LOGS(ERROR)
         << "BluetoothBwuHandler failed to parse UpgradePathInfo.";
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   const std::string& service_name = bluetooth_credentials.service_name();
@@ -64,7 +77,7 @@ BluetoothBwuHandler::CreateUpgradedEndpointChannel(
         << "BluetoothBwuHandler failed to derive a valid Bluetooth device "
            "from the MAC address ("
         << mac_address << ") for endpoint " << endpoint_id;
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   BluetoothSocket socket = bluetooth_medium_.Connect(
@@ -74,7 +87,7 @@ BluetoothBwuHandler::CreateUpgradedEndpointChannel(
         << "BluetoothBwuHandler failed to connect to the Bluetooth device ("
         << service_name << ", " << mac_address << ") for endpoint "
         << endpoint_id << " and service ID " << service_id;
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   NEARBY_VLOG(1)
@@ -91,11 +104,11 @@ BluetoothBwuHandler::CreateUpgradedEndpointChannel(
         << service_name << ", " << mac_address << ") for endpoint "
         << endpoint_id << " and service ID " << service_id;
     socket.Close();
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   client->SetBluetoothMacAddress(endpoint_id, mac_address);
-  return channel;
+  return {std::move(channel)};
 }
 
 ByteArray BluetoothBwuHandler::HandleInitializeUpgradedMediumForEndpoint(
@@ -146,7 +159,7 @@ void BluetoothBwuHandler::HandleRevertInitiatorStateForService(
 void BluetoothBwuHandler::OnIncomingBluetoothConnection(
     ClientProxy* client, const std::string& upgrade_service_id,
     BluetoothSocket socket) {
-  auto channel = absl::make_unique<BluetoothEndpointChannel>(
+  auto channel = std::make_unique<BluetoothEndpointChannel>(
       upgrade_service_id, /*channel_name=*/upgrade_service_id, socket);
   std::unique_ptr<IncomingSocketConnection> connection{
       new IncomingSocketConnection{
diff --git a/connections/implementation/bluetooth_bwu_handler.h b/connections/implementation/bluetooth_bwu_handler.h
index 6563eebf..46466ee2 100644
--- a/connections/implementation/bluetooth_bwu_handler.h
+++ b/connections/implementation/bluetooth_bwu_handler.h
@@ -15,14 +15,20 @@
 #ifndef CORE_INTERNAL_BLUETOOTH_BWU_HANDLER_H_
 #define CORE_INTERNAL_BLUETOOTH_BWU_HANDLER_H_
 
+#include <memory>
 #include <string>
+#include <utility>
 
 #include "connections/implementation/base_bwu_handler.h"
 #include "connections/implementation/client_proxy.h"
+#include "connections/implementation/endpoint_channel.h"
+#include "connections/implementation/mediums/bluetooth_classic.h"
+#include "connections/implementation/mediums/bluetooth_radio.h"
 #include "connections/implementation/mediums/mediums.h"
-#include "connections/implementation/mediums/utils.h"
+#include "connections/medium_selector.h"
 #include "internal/platform/bluetooth_classic.h"
-#include "internal/platform/count_down_latch.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
 
 namespace nearby {
 namespace connections {
@@ -51,10 +57,11 @@ class BluetoothBwuHandler : public BaseBwuHandler {
   };
 
   // BwuHandler implementation:
-  std::unique_ptr<EndpointChannel> CreateUpgradedEndpointChannel(
-      ClientProxy* client, const std::string& service_id,
-      const std::string& endpoint_id,
-      const UpgradePathInfo& upgrade_path_info) final;
+  ErrorOr<std::unique_ptr<EndpointChannel>>
+  CreateUpgradedEndpointChannel(ClientProxy* client,
+                                const std::string& service_id,
+                                const std::string& endpoint_id,
+                                const UpgradePathInfo& upgrade_path_info) final;
   Medium GetUpgradeMedium() const final { return Medium::BLUETOOTH; }
   void OnEndpointDisconnect(ClientProxy* client,
                             const std::string& endpoint_id) final {}
diff --git a/connections/implementation/bluetooth_bwu_test.cc b/connections/implementation/bluetooth_bwu_test.cc
index 6b0b9897..5e1631c5 100644
--- a/connections/implementation/bluetooth_bwu_test.cc
+++ b/connections/implementation/bluetooth_bwu_test.cc
@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #include <memory>
+#include <utility>
 
 #include "gtest/gtest.h"
 #include "absl/time/time.h"
@@ -25,6 +26,7 @@
 #include "internal/platform/byte_array.h"
 #include "internal/platform/count_down_latch.h"
 #include "internal/platform/exception.h"
+#include "internal/platform/expected.h"
 #include "internal/platform/feature_flags.h"
 #include "internal/platform/logging.h"
 #include "internal/platform/medium_environment.h"
@@ -35,6 +37,7 @@ namespace connections {
 
 namespace {
 using ::location::nearby::connections::OfflineFrame;
+using ::location::nearby::proto::connections::OperationResultCode;
 constexpr absl::Duration kWaitDuration = absl::Milliseconds(1000);
 }  // namespace
 
@@ -101,17 +104,22 @@ TEST_F(BluetoothBwuTest, SoftAPBWUInit_STACreateEndpointChannel) {
     auto bwu_frame =
         upgrade_frame.result().v1().bandwidth_upgrade_negotiation();
 
-    std::unique_ptr<EndpointChannel> new_channel =
+    ErrorOr<std::unique_ptr<EndpointChannel>> result =
         handler_2->CreateUpgradedEndpointChannel(&client_2, /*service_id=*/"A",
                                                  /*endpoint_id=*/"1",
                                                  bwu_frame.upgrade_path_info());
     if (!FeatureFlags::GetInstance().GetFlags().enable_cancellation_flag) {
+      ASSERT_TRUE(result.has_value());
+      std::unique_ptr<EndpointChannel> new_channel = std::move(result.value());
       EXPECT_TRUE(accept_latch.Await(kWaitDuration).result());
       EXPECT_EQ(new_channel->GetMedium(),
                 location::nearby::proto::connections::Medium::BLUETOOTH);
     } else {
+      EXPECT_FALSE(result.has_value());
+      EXPECT_TRUE(result.has_error());
+      EXPECT_EQ(result.error().operation_result_code(),
+                OperationResultCode::DETAIL_UNKNOWN);
       accept_latch.CountDown();
-      EXPECT_EQ(new_channel, nullptr);
     }
     EXPECT_FALSE(mediums_2.GetBluetoothClassic().GetMacAddress().empty());
     handler_2->RevertResponderState(/*service_id=*/"A");
diff --git a/connections/implementation/bwu_handler.h b/connections/implementation/bwu_handler.h
index de1ee7e0..0deb84bc 100644
--- a/connections/implementation/bwu_handler.h
+++ b/connections/implementation/bwu_handler.h
@@ -15,14 +15,15 @@
 #ifndef CORE_INTERNAL_BWU_HANDLER_H_
 #define CORE_INTERNAL_BWU_HANDLER_H_
 
-#include <functional>
+#include <memory>
 #include <string>
 
 #include "absl/functional/any_invocable.h"
 #include "connections/implementation/client_proxy.h"
 #include "connections/implementation/endpoint_channel.h"
 #include "connections/implementation/offline_frames.h"
-#include "internal/platform/count_down_latch.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
 
 namespace nearby {
 namespace connections {
@@ -81,14 +82,16 @@ class BwuHandler {
   // that hasn't already been done) using the UpgradePathInfo sent by the
   // Initiator, and returns a new EndpointChannel for the upgraded medium.
   // @BwuHandlerThread
-  virtual std::unique_ptr<EndpointChannel> CreateUpgradedEndpointChannel(
-      ClientProxy* client, const std::string& service_id,
-      const std::string& endpoint_id,
-      const UpgradePathInfo& upgrade_path_info) = 0;
+  virtual ErrorOr<std::unique_ptr<EndpointChannel>>
+  CreateUpgradedEndpointChannel(ClientProxy* client,
+                                const std::string& service_id,
+                                const std::string& endpoint_id,
+                                const UpgradePathInfo& upgrade_path_info) = 0;
 
   // Returns the upgrade medium of the BwuHandler.
   // @BwuHandlerThread
-  virtual Medium GetUpgradeMedium() const = 0;
+  virtual location::nearby::proto::connections::Medium GetUpgradeMedium()
+      const = 0;
 
   virtual void OnEndpointDisconnect(ClientProxy* client,
                                     const std::string& endpoint_id) = 0;
diff --git a/connections/implementation/bwu_manager.cc b/connections/implementation/bwu_manager.cc
index 362f834a..f448b46f 100644
--- a/connections/implementation/bwu_manager.cc
+++ b/connections/implementation/bwu_manager.cc
@@ -45,6 +45,7 @@
 #include "internal/platform/byte_array.h"
 #include "internal/platform/cancelable_alarm.h"
 #include "internal/platform/count_down_latch.h"
+#include "internal/platform/expected.h"
 #include "internal/platform/feature_flags.h"
 #include "internal/platform/implementation/system_clock.h"
 #include "internal/platform/logging.h"
@@ -882,10 +883,10 @@ BwuManager::ProcessBwuPathAvailableEventInternal(
     service_id = old_channel->GetServiceId();
   }
 
-  std::unique_ptr<EndpointChannel> new_channel =
+  ErrorOr<std::unique_ptr<EndpointChannel>> result =
       handler->CreateUpgradedEndpointChannel(client, service_id, endpoint_id,
                                              upgrade_path_info);
-  if (!new_channel) {
+  if (result.has_error() || !result.has_value()) {
     NEARBY_LOGS(ERROR) << "BwuManager failed to create an endpoint "
                           "channel to endpoint"
                        << endpoint_id << ", aborting upgrade.";
@@ -894,6 +895,7 @@ BwuManager::ProcessBwuPathAvailableEventInternal(
         location::nearby::proto::connections::SOCKET_CREATION);
     return nullptr;
   }
+  std::unique_ptr<EndpointChannel> new_channel = std::move(result.value());
 
   // Write the requisite BANDWIDTH_UPGRADE_NEGOTIATION.CLIENT_INTRODUCTION as
   // the first OfflineFrame on this new EndpointChannel.
diff --git a/connections/implementation/fake_bwu_handler.h b/connections/implementation/fake_bwu_handler.h
index 6f9aaa91..d87e99f2 100644
--- a/connections/implementation/fake_bwu_handler.h
+++ b/connections/implementation/fake_bwu_handler.h
@@ -15,6 +15,7 @@
 #ifndef NEARBY_CONNECTIONS_IMPLEMENTATION_FAKE_BWU_HANDLER_H_
 #define NEARBY_CONNECTIONS_IMPLEMENTATION_FAKE_BWU_HANDLER_H_
 
+#include <cstddef>
 #include <memory>
 #include <optional>
 #include <string>
@@ -22,9 +23,15 @@
 #include <vector>
 
 #include "connections/implementation/base_bwu_handler.h"
+#include "connections/implementation/bwu_handler.h"
 #include "connections/implementation/bwu_manager.h"
 #include "connections/implementation/client_proxy.h"
+#include "connections/implementation/endpoint_channel.h"
 #include "connections/implementation/fake_endpoint_channel.h"
+#include "connections/implementation/offline_frames.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/exception.h"
+#include "internal/platform/expected.h"
 
 namespace nearby {
 namespace connections {
@@ -104,14 +111,15 @@ class FakeBwuHandler : public BaseBwuHandler {
   };
 
   // BwuHandler:
-  std::unique_ptr<EndpointChannel> CreateUpgradedEndpointChannel(
+  ErrorOr<std::unique_ptr<EndpointChannel>>
+  CreateUpgradedEndpointChannel(
       ClientProxy* client, const std::string& service_id,
       const std::string& endpoint_id,
       const UpgradePathInfo& upgrade_path_info) final {
     create_calls_.push_back({.client = client,
                              .service_id = service_id,
                              .endpoint_id = endpoint_id});
-    return std::make_unique<FakeEndpointChannel>(medium_, service_id);
+    return {std::make_unique<FakeEndpointChannel>(medium_, service_id)};
   }
 
   Medium GetUpgradeMedium() const final { return medium_; }
diff --git a/connections/implementation/webrtc_bwu_handler.cc b/connections/implementation/webrtc_bwu_handler.cc
index 8d2b0652..3b470f23 100644
--- a/connections/implementation/webrtc_bwu_handler.cc
+++ b/connections/implementation/webrtc_bwu_handler.cc
@@ -32,13 +32,19 @@
 #include "connections/implementation/offline_frames.h"
 #include "connections/implementation/webrtc_endpoint_channel.h"
 #include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
 #include "internal/platform/logging.h"
 
 namespace nearby {
 namespace connections {
+
+namespace {
 using ::location::nearby::connections::LocationHint;
 using ::location::nearby::connections::LocationStandard;
+using ::location::nearby::proto::connections::OperationResultCode;
+}  // namespace
 
+// TODO(edwinwu): Add exact OperationResultCode for WebrtcBwuHandler.
 WebrtcBwuHandler::WebrtcIncomingSocket::WebrtcIncomingSocket(
     const std::string& name, mediums::WebRtcSocketWrapper socket)
     : name_(name), socket_(socket) {}
@@ -54,7 +60,7 @@ WebrtcBwuHandler::WebrtcBwuHandler(
 
 // Called by BWU target. Retrieves a new medium info from incoming message,
 // and establishes connection over WebRTC using this info.
-std::unique_ptr<EndpointChannel>
+ErrorOr<std::unique_ptr<EndpointChannel>>
 WebrtcBwuHandler::CreateUpgradedEndpointChannel(
     ClientProxy* client, const std::string& service_id,
     const std::string& endpoint_id, const UpgradePathInfo& upgrade_path_info) {
@@ -79,7 +85,7 @@ WebrtcBwuHandler::CreateUpgradedEndpointChannel(
     NEARBY_LOGS(ERROR) << "WebRtcBwuHandler failed to connect to remote peer ("
                        << peer_id.GetId() << ") on endpoint " << endpoint_id
                        << ", aborting upgrade.";
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   NEARBY_LOGS(INFO) << "WebRtcBwuHandler successfully connected to remote "
@@ -95,9 +101,10 @@ WebrtcBwuHandler::CreateUpgradedEndpointChannel(
     NEARBY_LOGS(ERROR)
         << "WebRtcBwuHandler failed to create new EndpointChannel for "
            "outgoing socket, aborting upgrade.";
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
-  return channel;
+  return {std::move(channel)};
 }
 
 void WebrtcBwuHandler::HandleRevertInitiatorStateForService(
diff --git a/connections/implementation/webrtc_bwu_handler.h b/connections/implementation/webrtc_bwu_handler.h
index 97e6cf44..8ad821b8 100644
--- a/connections/implementation/webrtc_bwu_handler.h
+++ b/connections/implementation/webrtc_bwu_handler.h
@@ -19,6 +19,7 @@
 
 #include <memory>
 #include <string>
+#include <utility>
 
 #include "connections/implementation/base_bwu_handler.h"
 #include "connections/implementation/bwu_handler.h"
@@ -29,6 +30,7 @@
 #include "connections/implementation/mediums/webrtc_socket.h"
 #include "connections/medium_selector.h"
 #include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
 
 namespace nearby {
 namespace connections {
@@ -56,11 +58,14 @@ class WebrtcBwuHandler : public BaseBwuHandler {
   };
 
   // BwuHandler implementation:
-  std::unique_ptr<EndpointChannel> CreateUpgradedEndpointChannel(
-      ClientProxy* client, const std::string& service_id,
-      const std::string& endpoint_id,
-      const UpgradePathInfo& upgrade_path_info) final;
-  Medium GetUpgradeMedium() const final { return Medium::WEB_RTC; }
+  ErrorOr<std::unique_ptr<EndpointChannel>>
+  CreateUpgradedEndpointChannel(ClientProxy* client,
+                                const std::string& service_id,
+                                const std::string& endpoint_id,
+                                const UpgradePathInfo& upgrade_path_info) final;
+  location::nearby::proto::connections::Medium GetUpgradeMedium() const final {
+    return Medium::WEB_RTC;
+  }
   void OnEndpointDisconnect(ClientProxy* client,
                             const std::string& endpoint_id) final {}
 
diff --git a/connections/implementation/webrtc_bwu_handler_stub.cc b/connections/implementation/webrtc_bwu_handler_stub.cc
index 91f19c1f..4bbb292f 100644
--- a/connections/implementation/webrtc_bwu_handler_stub.cc
+++ b/connections/implementation/webrtc_bwu_handler_stub.cc
@@ -25,10 +25,15 @@
 #include "connections/implementation/mediums/webrtc_peer_id_stub.h"
 #include "connections/implementation/offline_frames.h"
 #include "connections/implementation/webrtc_endpoint_channel.h"
+#include "internal/platform/expected.h"
 
 namespace nearby {
 namespace connections {
 
+namespace {
+using ::location::nearby::proto::connections::OperationResultCode;
+}  // namespace
+
 WebrtcBwuHandler::WebrtcIncomingSocket::WebrtcIncomingSocket(
     const std::string& name, mediums::WebRtcSocketWrapper socket)
     : name_(name), socket_(socket) {}
@@ -44,11 +49,11 @@ WebrtcBwuHandler::WebrtcBwuHandler(
 
 // Called by BWU target. Retrieves a new medium info from incoming message,
 // and establishes connection over WebRTC using this info.
-std::unique_ptr<EndpointChannel>
+ErrorOr<std::unique_ptr<EndpointChannel>>
 WebrtcBwuHandler::CreateUpgradedEndpointChannel(
     ClientProxy* client, const std::string& service_id,
     const std::string& endpoint_id, const UpgradePathInfo& upgrade_path_info) {
-  return nullptr;
+  return {Error(OperationResultCode::DETAIL_UNKNOWN)};
 }
 
 void WebrtcBwuHandler::HandleRevertInitiatorStateForService(
diff --git a/connections/implementation/webrtc_bwu_handler_stub.h b/connections/implementation/webrtc_bwu_handler_stub.h
index de0a9ff1..e3b0aebb 100644
--- a/connections/implementation/webrtc_bwu_handler_stub.h
+++ b/connections/implementation/webrtc_bwu_handler_stub.h
@@ -28,6 +28,7 @@
 #else
 #include "connections/implementation/mediums/webrtc_socket.h"
 #endif
+#include "internal/platform/expected.h"
 
 namespace nearby {
 namespace connections {
@@ -55,11 +56,14 @@ class WebrtcBwuHandler : public BaseBwuHandler {
   };
 
   // BwuHandler implementation:
-  std::unique_ptr<EndpointChannel> CreateUpgradedEndpointChannel(
-      ClientProxy* client, const std::string& service_id,
-      const std::string& endpoint_id,
-      const UpgradePathInfo& upgrade_path_info) final;
-  Medium GetUpgradeMedium() const final { return Medium::WEB_RTC; }
+  ErrorOr<std::unique_ptr<EndpointChannel>>
+  CreateUpgradedEndpointChannel(ClientProxy* client,
+                                const std::string& service_id,
+                                const std::string& endpoint_id,
+                                const UpgradePathInfo& upgrade_path_info) final;
+  location::nearby::proto::connections::Medium GetUpgradeMedium() const final {
+    return Medium::WEB_RTC;
+  }
   void OnEndpointDisconnect(ClientProxy* client,
                             const std::string& endpoint_id) final {}
 
diff --git a/connections/implementation/wifi_direct_bwu_handler.cc b/connections/implementation/wifi_direct_bwu_handler.cc
index 742aa002..e7e11157 100644
--- a/connections/implementation/wifi_direct_bwu_handler.cc
+++ b/connections/implementation/wifi_direct_bwu_handler.cc
@@ -15,7 +15,6 @@
 #include "connections/implementation/wifi_direct_bwu_handler.h"
 
 #include <cstdint>
-#include <locale>
 #include <memory>
 #include <string>
 #include <utility>
@@ -28,6 +27,7 @@
 #include "connections/implementation/offline_frames.h"
 #include "connections/implementation/wifi_direct_endpoint_channel.h"
 #include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
 #include "internal/platform/logging.h"
 #include "internal/platform/wifi_credential.h"
 #include "internal/platform/wifi_direct.h"
@@ -35,6 +35,11 @@
 namespace nearby {
 namespace connections {
 
+namespace {
+using ::location::nearby::proto::connections::OperationResultCode;
+}  // namespace
+
+// TODO(edwinwu): Add exact OperationResultCode for WifiDirectBwuHandler.
 WifiDirectBwuHandler::WifiDirectBwuHandler(
     Mediums& mediums, IncomingConnectionCallback incoming_connection_callback)
     : BaseBwuHandler(std::move(incoming_connection_callback)),
@@ -101,13 +106,13 @@ void WifiDirectBwuHandler::HandleRevertInitiatorStateForService(
       << "upgrade service ID " << upgrade_service_id;
 }
 
-std::unique_ptr<EndpointChannel>
+ErrorOr<std::unique_ptr<EndpointChannel>>
 WifiDirectBwuHandler::CreateUpgradedEndpointChannel(
     ClientProxy* client, const std::string& service_id,
     const std::string& endpoint_id, const UpgradePathInfo& upgrade_path_info) {
   if (!upgrade_path_info.has_wifi_direct_credentials()) {
     NEARBY_LOGS(INFO) << "No WifiDirect Credential";
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
   const UpgradePathInfo::WifiDirectCredentials& upgrade_path_info_credentials =
       upgrade_path_info.wifi_direct_credentials();
@@ -123,7 +128,7 @@ WifiDirectBwuHandler::CreateUpgradedEndpointChannel(
 
   if (!wifi_direct_medium_.ConnectWifiDirect(ssid, password)) {
     NEARBY_LOGS(ERROR) << "Connect to WifiDiret GO failed";
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   WifiDirectSocket socket = wifi_direct_medium_.Connect(
@@ -132,7 +137,7 @@ WifiDirectBwuHandler::CreateUpgradedEndpointChannel(
     NEARBY_LOGS(ERROR)
         << "WifiDirectBwuHandler failed to connect to the WifiDirect service("
         << port << ") for endpoint " << endpoint_id;
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   NEARBY_VLOG(1)
@@ -140,8 +145,8 @@ WifiDirectBwuHandler::CreateUpgradedEndpointChannel(
       << port << ") while upgrading endpoint " << endpoint_id;
 
   // Create a new WifiDirectEndpointChannel.
-  return std::make_unique<WifiDirectEndpointChannel>(
-      service_id, /*channel_name=*/service_id, socket);
+  return {std::make_unique<WifiDirectEndpointChannel>(
+              service_id, /*channel_name=*/service_id, socket)};
 }
 
 void WifiDirectBwuHandler::OnIncomingWifiDirectConnection(
diff --git a/connections/implementation/wifi_direct_bwu_handler.h b/connections/implementation/wifi_direct_bwu_handler.h
index e7f159ea..c189b87d 100644
--- a/connections/implementation/wifi_direct_bwu_handler.h
+++ b/connections/implementation/wifi_direct_bwu_handler.h
@@ -19,8 +19,16 @@
 #include <string>
 
 #include "connections/implementation/base_bwu_handler.h"
+#include "connections/implementation/bwu_handler.h"
 #include "connections/implementation/client_proxy.h"
+#include "connections/implementation/endpoint_channel.h"
 #include "connections/implementation/mediums/mediums.h"
+#include "connections/implementation/mediums/wifi.h"
+#include "connections/implementation/mediums/wifi_direct.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
+#include "internal/platform/wifi_direct.h"
+#include "utility"
 
 namespace nearby {
 namespace connections {
@@ -53,11 +61,14 @@ class WifiDirectBwuHandler : public BaseBwuHandler {
   // WFD protocol to established connection while WINRT follow the standard WFD
   // spec to achieve the connection. So return fail to stop the upgrade request
   // from phone side.
-  std::unique_ptr<EndpointChannel> CreateUpgradedEndpointChannel(
-      ClientProxy* client, const std::string& service_id,
-      const std::string& endpoint_id,
-      const UpgradePathInfo& upgrade_path_info) final;
-  Medium GetUpgradeMedium() const final { return Medium::WIFI_DIRECT; }
+  ErrorOr<std::unique_ptr<EndpointChannel>>
+  CreateUpgradedEndpointChannel(ClientProxy* client,
+                                const std::string& service_id,
+                                const std::string& endpoint_id,
+                                const UpgradePathInfo& upgrade_path_info) final;
+  location::nearby::proto::connections::Medium GetUpgradeMedium() const final {
+    return location::nearby::proto::connections::Medium::WIFI_DIRECT;
+  }
   void OnEndpointDisconnect(ClientProxy* client,
                             const std::string& endpoint_id) final {}
 
diff --git a/connections/implementation/wifi_direct_bwu_test.cc b/connections/implementation/wifi_direct_bwu_test.cc
index b01d9998..04d95412 100644
--- a/connections/implementation/wifi_direct_bwu_test.cc
+++ b/connections/implementation/wifi_direct_bwu_test.cc
@@ -16,16 +16,28 @@
 #include <utility>
 
 #include "gtest/gtest.h"
+#include "absl/time/time.h"
 #include "connections/implementation/bwu_handler.h"
+#include "connections/implementation/client_proxy.h"
+#include "connections/implementation/endpoint_channel.h"
+#include "connections/implementation/mediums/mediums.h"
+#include "connections/implementation/offline_frames.h"
 #include "connections/implementation/wifi_direct_bwu_handler.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/count_down_latch.h"
+#include "internal/platform/exception.h"
+#include "internal/platform/expected.h"
 #include "internal/platform/feature_flags.h"
+#include "internal/platform/logging.h"
 #include "internal/platform/medium_environment.h"
+#include "internal/platform/single_thread_executor.h"
 
 namespace nearby {
 namespace connections {
 
 namespace {
 using ::location::nearby::connections::OfflineFrame;
+using ::location::nearby::proto::connections::OperationResultCode;
 constexpr absl::Duration kWaitDuration = absl::Milliseconds(1000);
 }  // namespace
 
@@ -97,17 +109,22 @@ TEST_F(WifiDirectTest, WFDGOBWUInit_GCCreateEndpointChannel) {
     auto bwu_frame =
         upgrade_frame.result().v1().bandwidth_upgrade_negotiation();
 
-    std::unique_ptr<EndpointChannel> new_channel =
+    ErrorOr<std::unique_ptr<EndpointChannel>> result =
         handler_2->CreateUpgradedEndpointChannel(
             &wifi_direct_gc, /*service_id=*/"A",
             /*endpoint_id=*/"1", bwu_frame.upgrade_path_info());
     if (!FeatureFlags::GetInstance().GetFlags().enable_cancellation_flag) {
+      ASSERT_TRUE(result.has_value());
+      std::unique_ptr<EndpointChannel> new_channel = std::move(result.value());
       EXPECT_TRUE(accept_latch.Await(kWaitDuration).result());
       EXPECT_EQ(new_channel->GetMedium(),
                 location::nearby::proto::connections::Medium::WIFI_DIRECT);
     } else {
+      EXPECT_FALSE(result.has_value());
+      EXPECT_TRUE(result.has_error());
+      EXPECT_EQ(result.error().operation_result_code(),
+                OperationResultCode::DETAIL_UNKNOWN);
       accept_latch.CountDown();
-      EXPECT_EQ(new_channel, nullptr);
     }
     EXPECT_TRUE(mediums_2.GetWifiDirect().IsConnectedToGO());
     handler_2->RevertResponderState(/*service_id=*/"A");
diff --git a/connections/implementation/wifi_hotspot_bwu_handler.cc b/connections/implementation/wifi_hotspot_bwu_handler.cc
index 4e8b1247..43171578 100644
--- a/connections/implementation/wifi_hotspot_bwu_handler.cc
+++ b/connections/implementation/wifi_hotspot_bwu_handler.cc
@@ -15,7 +15,6 @@
 #include "connections/implementation/wifi_hotspot_bwu_handler.h"
 
 #include <cstdint>
-#include <locale>
 #include <memory>
 #include <string>
 #include <utility>
@@ -25,11 +24,11 @@
 #include "connections/implementation/client_proxy.h"
 #include "connections/implementation/endpoint_channel.h"
 #include "connections/implementation/mediums/mediums.h"
-#include "connections/implementation/mediums/utils.h"
 #include "connections/implementation/offline_frames.h"
 #include "connections/implementation/wifi_hotspot_endpoint_channel.h"
 #include "connections/strategy.h"
 #include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
 #include "internal/platform/logging.h"
 #include "internal/platform/wifi_credential.h"
 #include "internal/platform/wifi_hotspot.h"
@@ -37,6 +36,11 @@
 namespace nearby {
 namespace connections {
 
+namespace {
+using ::location::nearby::proto::connections::OperationResultCode;
+}  // namespace
+
+// TODO(edwinwu): Add exact OperationResultCode for WifiHotspotBwuHandler.
 WifiHotspotBwuHandler::WifiHotspotBwuHandler(
     Mediums& mediums, IncomingConnectionCallback incoming_connection_callback)
     : BaseBwuHandler(std::move(incoming_connection_callback)),
@@ -108,13 +112,13 @@ void WifiHotspotBwuHandler::HandleRevertInitiatorStateForService(
 
 // Called by BWU target. Retrieves a new medium info from incoming message,
 // and establishes connection over WifiHotspot using this info.
-std::unique_ptr<EndpointChannel>
+ErrorOr<std::unique_ptr<EndpointChannel>>
 WifiHotspotBwuHandler::CreateUpgradedEndpointChannel(
     ClientProxy* client, const std::string& service_id,
     const std::string& endpoint_id, const UpgradePathInfo& upgrade_path_info) {
   if (!upgrade_path_info.has_wifi_hotspot_credentials()) {
     NEARBY_LOGS(INFO) << "No Hotspot Credential";
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
   const UpgradePathInfo::WifiHotspotCredentials& upgrade_path_info_credentials =
       upgrade_path_info.wifi_hotspot_credentials();
@@ -131,7 +135,7 @@ WifiHotspotBwuHandler::CreateUpgradedEndpointChannel(
 
   if (!wifi_hotspot_medium_.ConnectWifiHotspot(ssid, password, frequency)) {
     NEARBY_LOGS(ERROR) << "Connect to Hotspot failed";
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   WifiHotspotSocket socket = wifi_hotspot_medium_.Connect(
@@ -140,7 +144,7 @@ WifiHotspotBwuHandler::CreateUpgradedEndpointChannel(
     NEARBY_LOGS(ERROR)
         << "WifiHotspotBwuHandler failed to connect to the WifiHotspot service("
         << gateway << ":" << port << ") for endpoint " << endpoint_id;
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   NEARBY_VLOG(1)
@@ -151,7 +155,7 @@ WifiHotspotBwuHandler::CreateUpgradedEndpointChannel(
   auto channel = std::make_unique<WifiHotspotEndpointChannel>(
       service_id, /*channel_name=*/service_id, socket);
 
-  return channel;
+  return {std::move(channel)};
 }
 
 // Accept Connection Callback.
diff --git a/connections/implementation/wifi_hotspot_bwu_handler.h b/connections/implementation/wifi_hotspot_bwu_handler.h
index 3e4fd611..f19f708d 100644
--- a/connections/implementation/wifi_hotspot_bwu_handler.h
+++ b/connections/implementation/wifi_hotspot_bwu_handler.h
@@ -15,12 +15,19 @@
 #ifndef CORE_INTERNAL_WIFI_HOTSPOT_BWU_HANDLER_H_
 #define CORE_INTERNAL_WIFI_HOTSPOT_BWU_HANDLER_H_
 
+#include <memory>
 #include <string>
+#include <utility>
 
 #include "connections/implementation/base_bwu_handler.h"
+#include "connections/implementation/bwu_handler.h"
 #include "connections/implementation/client_proxy.h"
-#include "connections/implementation/endpoint_channel_manager.h"
+#include "connections/implementation/endpoint_channel.h"
 #include "connections/implementation/mediums/mediums.h"
+#include "connections/implementation/mediums/wifi_hotspot.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
+#include "internal/platform/wifi_hotspot.h"
 
 namespace nearby {
 namespace connections {
@@ -49,11 +56,14 @@ class WifiHotspotBwuHandler : public BaseBwuHandler {
   };
 
   // BwuHandler implementation:
-  std::unique_ptr<EndpointChannel> CreateUpgradedEndpointChannel(
-      ClientProxy* client, const std::string& service_id,
-      const std::string& endpoint_id,
-      const UpgradePathInfo& upgrade_path_info) final;
-  Medium GetUpgradeMedium() const final { return Medium::WIFI_HOTSPOT; }
+  ErrorOr<std::unique_ptr<EndpointChannel>>
+  CreateUpgradedEndpointChannel(ClientProxy* client,
+                                const std::string& service_id,
+                                const std::string& endpoint_id,
+                                const UpgradePathInfo& upgrade_path_info) final;
+  location::nearby::proto::connections::Medium GetUpgradeMedium() const final {
+    return location::nearby::proto::connections::Medium::WIFI_HOTSPOT;
+  }
   void OnEndpointDisconnect(ClientProxy* client,
                             const std::string& endpoint_id) final {}
 
diff --git a/connections/implementation/wifi_hotspot_bwu_test.cc b/connections/implementation/wifi_hotspot_bwu_test.cc
index 091087c3..44a47333 100644
--- a/connections/implementation/wifi_hotspot_bwu_test.cc
+++ b/connections/implementation/wifi_hotspot_bwu_test.cc
@@ -12,19 +12,32 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include <memory>
 #include <utility>
 
 #include "gtest/gtest.h"
+#include "absl/time/time.h"
 #include "connections/implementation/bwu_handler.h"
+#include "connections/implementation/client_proxy.h"
+#include "connections/implementation/endpoint_channel.h"
+#include "connections/implementation/mediums/mediums.h"
+#include "connections/implementation/offline_frames.h"
 #include "connections/implementation/wifi_hotspot_bwu_handler.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/count_down_latch.h"
+#include "internal/platform/exception.h"
+#include "internal/platform/expected.h"
 #include "internal/platform/feature_flags.h"
+#include "internal/platform/logging.h"
 #include "internal/platform/medium_environment.h"
+#include "internal/platform/single_thread_executor.h"
 
 namespace nearby {
 namespace connections {
 
 namespace {
 using ::location::nearby::connections::OfflineFrame;
+using ::location::nearby::proto::connections::OperationResultCode;
 constexpr absl::Duration kWaitDuration = absl::Milliseconds(1000);
 }  // namespace
 
@@ -91,17 +104,22 @@ TEST_F(WifiHotspotTest, SoftAPBWUInit_STACreateEndpointChannel) {
     auto bwu_frame =
         upgrade_frame.result().v1().bandwidth_upgrade_negotiation();
 
-    std::unique_ptr<EndpointChannel> new_channel =
+    ErrorOr<std::unique_ptr<EndpointChannel>> result =
         handler_2->CreateUpgradedEndpointChannel(&client_2, /*service_id=*/"A",
                                                  /*endpoint_id=*/"1",
                                                  bwu_frame.upgrade_path_info());
     if (!FeatureFlags::GetInstance().GetFlags().enable_cancellation_flag) {
+      ASSERT_TRUE(result.has_value());
+      std::unique_ptr<EndpointChannel> new_channel = std::move(result.value());
       EXPECT_TRUE(accept_latch.Await(kWaitDuration).result());
       EXPECT_EQ(new_channel->GetMedium(),
                 location::nearby::proto::connections::Medium::WIFI_HOTSPOT);
     } else {
+      EXPECT_FALSE(result.has_value());
+      EXPECT_TRUE(result.has_error());
+      EXPECT_EQ(result.error().operation_result_code(),
+                OperationResultCode::DETAIL_UNKNOWN);
       accept_latch.CountDown();
-      EXPECT_EQ(new_channel, nullptr);
     }
     EXPECT_TRUE(mediums_2.GetWifiHotspot().IsConnectedToHotspot());
     handler_2->RevertResponderState(/*service_id=*/"A");
diff --git a/connections/implementation/wifi_lan_bwu_handler.cc b/connections/implementation/wifi_lan_bwu_handler.cc
index b1cb3650..04c751f6 100644
--- a/connections/implementation/wifi_lan_bwu_handler.cc
+++ b/connections/implementation/wifi_lan_bwu_handler.cc
@@ -14,13 +14,20 @@
 
 #include "connections/implementation/wifi_lan_bwu_handler.h"
 
+#include <cstdint>
+#include <memory>
 #include <string>
 #include <utility>
 
 #include "absl/functional/bind_front.h"
+#include "connections/implementation/base_bwu_handler.h"
 #include "connections/implementation/client_proxy.h"
+#include "connections/implementation/endpoint_channel.h"
+#include "connections/implementation/mediums/mediums.h"
 #include "connections/implementation/offline_frames.h"
 #include "connections/implementation/wifi_lan_endpoint_channel.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
 #include "internal/platform/implementation/wifi_utils.h"
 #include "internal/platform/logging.h"
 #include "internal/platform/wifi_lan.h"
@@ -28,6 +35,11 @@
 namespace nearby {
 namespace connections {
 
+namespace {
+using ::location::nearby::proto::connections::OperationResultCode;
+}  // namespace
+
+// TODO(edwinwu): Add exact OperationResultCode for WifiLanBwuHandler.
 WifiLanBwuHandler::WifiLanBwuHandler(
     Mediums& mediums, IncomingConnectionCallback incoming_connection_callback)
     : BaseBwuHandler(std::move(incoming_connection_callback)),
@@ -35,19 +47,19 @@ WifiLanBwuHandler::WifiLanBwuHandler(
 
 // Called by BWU target. Retrieves a new medium info from incoming message,
 // and establishes connection over WifiLan using this info.
-std::unique_ptr<EndpointChannel>
+ErrorOr<std::unique_ptr<EndpointChannel>>
 WifiLanBwuHandler::CreateUpgradedEndpointChannel(
     ClientProxy* client, const std::string& service_id,
     const std::string& endpoint_id, const UpgradePathInfo& upgrade_path_info) {
   if (!upgrade_path_info.has_wifi_lan_socket()) {
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
   const UpgradePathInfo::WifiLanSocket& upgrade_path_info_socket =
       upgrade_path_info.wifi_lan_socket();
   if (!upgrade_path_info_socket.has_ip_address() ||
       !upgrade_path_info_socket.has_wifi_port()) {
     NEARBY_LOGS(ERROR) << "WifiLanBwuHandler failed to parse UpgradePathInfo.";
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   const std::string& ip_address = upgrade_path_info_socket.ip_address();
@@ -64,7 +76,7 @@ WifiLanBwuHandler::CreateUpgradedEndpointChannel(
         << "WifiLanBwuHandler failed to connect to the WifiLan service ("
         << WifiUtils::GetHumanReadableIpAddress(ip_address) << ":" << port
         << ") for endpoint " << endpoint_id;
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
   NEARBY_VLOG(1)
@@ -80,10 +92,10 @@ WifiLanBwuHandler::CreateUpgradedEndpointChannel(
                        << "channel to the WifiLan service (" << ip_address
                        << ":" << port << ") for endpoint " << endpoint_id;
     socket.Close();
-    return nullptr;
+    return {Error(OperationResultCode::DETAIL_UNKNOWN)};
   }
 
-  return channel;
+  return {std::move(channel)};
 }
 
 // Called by BWU initiator. Set up WifiLan upgraded medium for this endpoint,
@@ -143,12 +155,12 @@ void WifiLanBwuHandler::HandleRevertInitiatorStateForService(
 void WifiLanBwuHandler::OnIncomingWifiLanConnection(
     ClientProxy* client, const std::string& upgrade_service_id,
     WifiLanSocket socket) {
-  auto channel = absl::make_unique<WifiLanEndpointChannel>(
+  auto channel = std::make_unique<WifiLanEndpointChannel>(
       upgrade_service_id, /*channel_name=*/upgrade_service_id, socket);
   std::unique_ptr<IncomingSocketConnection> connection(
       new IncomingSocketConnection{
-          .socket = absl::make_unique<WifiLanIncomingSocket>(upgrade_service_id,
-                                                             socket),
+          .socket = std::make_unique<WifiLanIncomingSocket>(upgrade_service_id,
+                                                            socket),
           .channel = std::move(channel),
       });
   NotifyOnIncomingConnection(client, std::move(connection));
diff --git a/connections/implementation/wifi_lan_bwu_handler.h b/connections/implementation/wifi_lan_bwu_handler.h
index aee1ae01..64bad310 100644
--- a/connections/implementation/wifi_lan_bwu_handler.h
+++ b/connections/implementation/wifi_lan_bwu_handler.h
@@ -15,12 +15,19 @@
 #ifndef CORE_INTERNAL_WIFI_LAN_BWU_HANDLER_H_
 #define CORE_INTERNAL_WIFI_LAN_BWU_HANDLER_H_
 
+#include <memory>
 #include <string>
+#include <utility>
 
 #include "connections/implementation/base_bwu_handler.h"
+#include "connections/implementation/bwu_handler.h"
 #include "connections/implementation/client_proxy.h"
-#include "connections/implementation/endpoint_channel_manager.h"
+#include "connections/implementation/endpoint_channel.h"
 #include "connections/implementation/mediums/mediums.h"
+#include "connections/implementation/mediums/wifi_lan.h"
+#include "internal/platform/byte_array.h"
+#include "internal/platform/expected.h"
+#include "internal/platform/wifi_lan.h"
 
 namespace nearby {
 namespace connections {
@@ -49,11 +56,14 @@ class WifiLanBwuHandler : public BaseBwuHandler {
   };
 
   // BwuHandler implementation:
-  std::unique_ptr<EndpointChannel> CreateUpgradedEndpointChannel(
-      ClientProxy* client, const std::string& service_id,
-      const std::string& endpoint_id,
-      const UpgradePathInfo& upgrade_path_info) final;
-  Medium GetUpgradeMedium() const final { return Medium::WIFI_LAN; }
+  ErrorOr<std::unique_ptr<EndpointChannel>>
+  CreateUpgradedEndpointChannel(ClientProxy* client,
+                                const std::string& service_id,
+                                const std::string& endpoint_id,
+                                const UpgradePathInfo& upgrade_path_info) final;
+  location::nearby::proto::connections::Medium GetUpgradeMedium() const final {
+    return location::nearby::proto::connections::Medium::WIFI_LAN;
+  }
   void OnEndpointDisconnect(ClientProxy* client,
                             const std::string& endpoint_id) final {}