bluetooth: Add DeviceChanged logging in Device service.

device/bluetooth/device.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 DEVICE_BLUETOOTH_DEVICE_H_
 #define DEVICE_BLUETOOTH_DEVICE_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "device/bluetooth/bluetooth_adapter.h"
 #include "device/bluetooth/bluetooth_device.h"
 #include "device/bluetooth/public/interfaces/device.mojom.h"
 
 namespace bluetooth {
 
 // Implementation of Mojo Device located in
 // device/bluetooth/public/interfaces/device.mojom.
 // It handles requests to interact with Bluetooth Device.
 // Uses the platform abstraction of device/bluetooth.
-class Device : public mojom::Device {
+class Device : public mojom::Device, public device::BluetoothAdapter::Observer {
  public:
   Device(const std::string& address,
          scoped_refptr<device::BluetoothAdapter> adapter);
   ~Device() override;
 
   // Creates a mojom::DeviceInfo using info from the given |device|.
   static mojom::DeviceInfoPtr ConstructDeviceInfoStruct(
       const device::BluetoothDevice* device);
 
+  // device::BluetoothAdapter::Observer overrides:
+  void DeviceChanged(device::BluetoothAdapter* adapter,
+                     device::BluetoothDevice* device) override;
+
   // mojom::Device overrides:
   void GetInfo(const GetInfoCallback& callback) override;
+  void SetClient(mojom::GattClientPtr client) override;
 
  private:
   // The address of the Bluetooth device.
   std::string address_;
 
   // The current BluetoothAdapter.
   scoped_refptr<device::BluetoothAdapter> adapter_;
 
+  // The current client which listens to events from this device.
+  mojom::GattClientPtr client_;
+
   DISALLOW_COPY_AND_ASSIGN(Device);
 };
 
 }  // namespace bluetooth
 
 #endif  // DEVICE_BLUETOOTH_DEVICE_H_