arc: bluetooth: Add/Remove BT observer only when ARC is ready

components/arc/bluetooth/arc_bluetooth_bridge.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_ARC_BLUETOOTH_ARC_BLUETOOTH_BRIDGE_H_
 #define COMPONENTS_ARC_BLUETOOTH_ARC_BLUETOOTH_BRIDGE_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 27 matching lines @@
       public device::BluetoothAdapter::Observer,
       public device::BluetoothAdapterFactory::AdapterCallback,
       public device::BluetoothLocalGattService::Delegate,
       public mojom::BluetoothHost {
  public:
   explicit ArcBluetoothBridge(ArcBridgeService* bridge_service);
   ~ArcBluetoothBridge() override;
 
   // Overridden from InstanceHolder<mojom::BluetoothInstance>::Observer:
   void OnInstanceReady() override;
+  void OnInstanceClosed() override;
 
   void OnAdapterInitialized(scoped_refptr<device::BluetoothAdapter> adapter);
 
   // Overridden from device::BluetoothAdadpter::Observer
   void AdapterPoweredChanged(device::BluetoothAdapter* adapter,
                              bool powered) override;
 
   void DeviceAdded(device::BluetoothAdapter* adapter,
                    device::BluetoothDevice* device) override;
 
@@ skipping 299 matching lines @@
                                    const std::vector<uint8_t>& value,
                                    int offset,
                                    const base::Closure& success_callback,
                                    const ErrorCallback& error_callback);
 
   bool CalledOnValidThread();
 
   mojo::Binding<mojom::BluetoothHost> binding_;
 
   scoped_refptr<bluez::BluetoothAdapterBlueZ> bluetooth_adapter_;
+  bool bluetooth_observer_flag_ = false;

[rkc, 2016/08/08 21:58:29]

The correct solution is just to add a HasObserver method to BluetoothAdapter.
Maintaining a flag for this shouldn't be done here.

   scoped_refptr<device::BluetoothAdvertisement> advertisment_;
   std::unique_ptr<device::BluetoothDiscoverySession> discovery_session_;
   std::unordered_map<std::string,
                      std::unique_ptr<device::BluetoothGattNotifySession>>
       notification_session_;
   // Map from Android int handle to Chrome (BlueZ) string identifier.
   std::unordered_map<int32_t, std::string> gatt_identifier_;
   // Map from Chrome (BlueZ) string identifier to android int handle.
   std::unordered_map<std::string, int32_t> gatt_handle_;
   // Store last GattCharacteristic added to each GattService for GattServer.
   std::unordered_map<int32_t, int32_t> last_characteristic_;
   // Monotonically increasing value to use as handle to give to Android side.
   int32_t gatt_server_attribute_next_handle_ = 0;
 
   base::ThreadChecker thread_checker_;
 
   // WeakPtrFactory to use for callbacks.
   base::WeakPtrFactory<ArcBluetoothBridge> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcBluetoothBridge);
 };
 
 }  // namespace arc
 
 #endif  // COMPONENTS_ARC_BLUETOOTH_ARC_BLUETOOTH_BRIDGE_H_