nearby: snapshot of cl/313536507

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: I8936b527079074d5c3af5531b9245063767cc4a7

cpp/platform_v2/impl/g3/medium_environment.cc

@@ -0,0 +1,32 @@
+#include "platform_v2/impl/g3/medium_environment.h"
+
+namespace location {
+namespace nearby {
+namespace g3 {
+
+MediumEnvironment& MediumEnvironment::Instance() {
+  static std::aligned_storage_t<sizeof(MediumEnvironment),
+                                alignof(MediumEnvironment)>
+      storage;
+  static MediumEnvironment* env = new (&storage) MediumEnvironment();
+  return *env;
+}
+
+void MediumEnvironment::Reset() {
+  absl::MutexLock lock(&mutex_);
+  bluetooth_adapters_.clear();
+}
+
+void MediumEnvironment::OnBluetoothAdapterChangedState(
+    BluetoothAdapter& adapter) {
+  absl::MutexLock lock(&mutex_);
+  // We don't care if there is an adapter already since all we store is a
+  // pointer.
+  bluetooth_adapters_.emplace(&adapter);
+  // TODO(apolyudov): Add event propagation code when Medium registration is
+  // implemented.
+}
+
+}  // namespace g3
+}  // namespace nearby
+}  // namespace location