Ash: Support "Next Song", "Previous Song", "Play/Pause" Multi Media buttons

ash/shell/shell_delegate_impl.cc

 // Copyright (c) 2012 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.
 
 #include "ash/shell/shell_delegate_impl.h"
 
 #include "ash/shell/example_factory.h"
 #include "ash/shell/launcher_delegate_impl.h"
 #include "ash/shell/toplevel_window.h"
 #include "ash/shell_window_ids.h"
@@ skipping 115 matching lines @@
 aura::client::UserActionClient* ShellDelegateImpl::CreateUserActionClient() {
   return NULL;
 }
 
 void ShellDelegateImpl::OpenFeedbackPage() {
 }
 
 void ShellDelegateImpl::RecordUserMetricsAction(UserMetricsAction action) {
 }
 
+void ShellDelegateImpl::HandleMediaNextTrack() {
+}
+
+void ShellDelegateImpl::HandleMediaPlayPause() {
+}
+
+void ShellDelegateImpl::HandleMediaPrevTrack() {
+}
+
 }  // namespace shell
 }  // namespace ash