Implement DBus changes needed for notifications.

device/bluetooth/dbus/bluetooth_gatt_descriptor_service_provider_impl.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_DBUS_BLUETOOTH_GATT_DESCRIPTOR_SERVICE_PROVIDER_IMPL_H_
 #define DEVICE_BLUETOOTH_DBUS_BLUETOOTH_GATT_DESCRIPTOR_SERVICE_PROVIDER_IMPL_H_
 
 #include <stdint.h>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/platform_thread.h"
 #include "dbus/bus.h"
 #include "dbus/exported_object.h"
 #include "dbus/message.h"
 #include "dbus/object_path.h"
 #include "device/bluetooth/dbus/bluetooth_gatt_attribute_value_delegate.h"
 #include "device/bluetooth/dbus/bluetooth_gatt_descriptor_service_provider.h"
 
 namespace bluez {
 
 // The BluetoothGattDescriptorServiceProvider implementation used in production.
 class DEVICE_BLUETOOTH_EXPORT BluetoothGattDescriptorServiceProviderImpl
     : public BluetoothGattDescriptorServiceProvider {
  public:
+  // Use nullptr for |bus| to create for testing.
   BluetoothGattDescriptorServiceProviderImpl(
       dbus::Bus* bus,
       const dbus::ObjectPath& object_path,
       std::unique_ptr<BluetoothGattAttributeValueDelegate> delegate,
       const std::string& uuid,
       const std::vector<std::string>& flags,
       const dbus::ObjectPath& characteristic_path);
   ~BluetoothGattDescriptorServiceProviderImpl() override;
 
   // BluetoothGattDescriptorServiceProvider override.
@@ skipping 89 matching lines @@
   // invalidate its weak pointers before any other members are destroyed.
   base::WeakPtrFactory<BluetoothGattDescriptorServiceProviderImpl>
       weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BluetoothGattDescriptorServiceProviderImpl);
 };
 
 }  // namespace bluez
 
 #endif  // DEVICE_BLUETOOTH_DBUS_BLUETOOTH_GATT_DESCRIPTOR_SERVICE_PROVIDER_IMPL_H_