Add support for sharing DiscoveryCallbacks across BluetoothDevices.

internal/platform/implementation/linux/bluetooth_classic_device.cc

@@ -163,6 +163,10 @@ void MonitoredBluetoothDevice::onPropertiesChanged(
       for (auto &observer : observers_.GetObservers()) {
         observer->DeviceConnectedStateChanged(*this, it->second);
       }
+    } else if (it->first == bluez::DEVICE_NAME) {
+      auto callback = discovery_cb_.lock();
+      if (callback != nullptr && callback->device_name_changed_cb != nullptr)
+        callback->device_name_changed_cb(*this);
     }
   }
 }

internal/platform/implementation/linux/bluetooth_classic_device.h

@@ -96,6 +96,12 @@ class MonitoredBluetoothDevice final
       ObserverList<api::BluetoothClassicMedium::Observer> &observers);
   ~MonitoredBluetoothDevice() override { unregisterProxy(); }
 
+  void SetDiscoveryCallback(
+      std::shared_ptr<api::BluetoothClassicMedium::DiscoveryCallback>
+          &callback) {
+    discovery_cb_ = callback;
+  };
+
  protected:
   void onPropertiesChanged(
       const std::string &interfaceName,
@@ -104,6 +110,7 @@ class MonitoredBluetoothDevice final
 
  private:
   ObserverList<api::BluetoothClassicMedium::Observer> &observers_;
+  std::weak_ptr<api::BluetoothClassicMedium::DiscoveryCallback> discovery_cb_;
 };
 
 }  // namespace linux

internal/platform/implementation/linux/bluetooth_classic_medium.cc

@@ -64,9 +64,9 @@ void BluetoothClassicMedium::onInterfacesAdded(
     NEARBY_LOGS(INFO) << __func__ << ": Encountered new device at " << object;
 
     auto device = devices_->add_new_device(object);
-
-    if (discovery_cb_.has_value() &&
+    if (discovery_cb_ != nullptr &&
         discovery_cb_->device_discovered_cb != nullptr) {
+      device->SetDiscoveryCallback(discovery_cb_);
       discovery_cb_->device_discovered_cb(*device);
     }
 
@@ -98,7 +98,7 @@ void BluetoothClassicMedium::onInterfacesRemoved(
 
         NEARBY_LOGS(INFO) << __func__ << ": Device " << object
                           << " has been removed";
-        if (discovery_cb_.has_value() &&
+        if (discovery_cb_ != nullptr &&
             discovery_cb_->device_lost_cb != nullptr) {
           discovery_cb_->device_lost_cb(*device);
         }
@@ -114,7 +114,8 @@ void BluetoothClassicMedium::onInterfacesRemoved(
 
 bool BluetoothClassicMedium::StartDiscovery(
     DiscoveryCallback discovery_callback) {
-  discovery_cb_ = std::move(discovery_callback);
+  discovery_cb_ =
+      std::make_shared<DiscoveryCallback>(std::move(discovery_callback));
 
   try {
     NEARBY_LOGS(INFO) << __func__ << ": Starting discovery on "

internal/platform/implementation/linux/bluetooth_classic_medium.h

@@ -122,7 +122,7 @@ class BluetoothClassicMedium final
   BluetoothAdapter adapter_;
   std::unique_ptr<BluetoothDevices> devices_;
 
-  std::optional<BluetoothClassicMedium::DiscoveryCallback> discovery_cb_;
+  std::shared_ptr<BluetoothClassicMedium::DiscoveryCallback> discovery_cb_;
 
   std::unique_ptr<ProfileManager> profile_manager_;
   ObserverList<Observer> observers_;

internal/platform/implementation/linux/bluetooth_devices.cc

@@ -49,7 +49,7 @@ void BluetoothDevices::remove_device_by_path(
   devices_by_path_.erase(device_object_path);
 }
 
-std::shared_ptr<BluetoothDevice> BluetoothDevices::add_new_device(
+std::shared_ptr<MonitoredBluetoothDevice> BluetoothDevices::add_new_device(
     sdbus::ObjectPath device_object_path) {
   absl::MutexLock l(&devices_by_path_lock_);
   auto pair = devices_by_path_.emplace(

internal/platform/implementation/linux/bluetooth_devices.h

@@ -43,7 +43,7 @@ class BluetoothDevices final {
   std::shared_ptr<BluetoothDevice> get_device_by_address(const std::string &);
   void remove_device_by_path(const sdbus::ObjectPath &)
       ABSL_LOCKS_EXCLUDED(devices_by_path_lock_);
-  std::shared_ptr<BluetoothDevice> add_new_device(sdbus::ObjectPath)
+  std::shared_ptr<MonitoredBluetoothDevice> add_new_device(sdbus::ObjectPath)
       ABSL_LOCKS_EXCLUDED(devices_by_path_lock_);
 
  private:

internal/platform/implementation/linux/bluez.h

@@ -43,6 +43,7 @@ static constexpr const char *DEVICE_PROP_ADDRESS = "Address";
 static constexpr const char *DEVICE_PROP_ALIAS = "Alias";
 static constexpr const char *DEVICE_PROP_PAIRED = "Paired";
 static constexpr const char *DEVICE_PROP_CONNECTED = "Connected";
+static constexpr const char *DEVICE_NAME = "Name";
 
 std::string device_object_path(const sdbus::ObjectPath &adapter_object_path,
                                absl::string_view mac_address);