Implement DBus changes needed for notifications.

device/bluetooth/dbus/bluetooth_gatt_attribute_value_delegate.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_ATTRIBUTE_VALUE_DELEGATE_H_
 #define DEVICE_BLUETOOTH_DBUS_BLUETOOTH_GATT_ATTRIBUTE_VALUE_DELEGATE_H_
 
 #include <cstdint>
 #include <vector>
 
@@ skipping 26 matching lines @@
   // that the value was successfully written. Invoke |error_callback| to
   // report a failure to write the value. This can happen, for example, if the
   // attribute has no write permission set. Either callback should be
   // invoked after a reasonable amount of time, since the request will time
   // out if left pending for too long causing a disconnection.
   virtual void SetValue(
       const std::vector<uint8_t>& value,
       const base::Closure& callback,
       const device::BluetoothLocalGattService::Delegate::ErrorCallback&
           error_callback) = 0;
+
+  // This method will be called, when a remote device requests to start sending
+  // notifications for this characteristic. This will never be called for
+  // descriptors.
+  virtual void StartNotifications() = 0;
+
+  // This method will be called, when a remote device requests to stop sending
+  // notifications for this characteristic. This will never be called for
+  // descriptors.
+  virtual void StopNotifications() = 0;
 };
 
 }  // namespace bluez
 
 #endif  // DEVICE_BLUETOOTH_DBUS_BLUETOOTH_GATT_ATTRIBUTE_VALUE_DELEGATE_H_