Implement mediaGalleriesPrivate api to notify extensions about gallery changed events.

chrome/browser/extensions/event_names.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 "chrome/browser/extensions/event_names.h"
 
 namespace extensions {
 
 namespace event_names {
 
@@ skipping 67 matching lines @@
 const char kOnStorageAdded[] = "experimental.systemInfo.storage.onAdded";
 const char kOnStorageRemoved[] = "experimental.systemInfo.storage.onRemoved";
 
 const char kOnSystemIndicatorClicked[] = "systemIndicator.onClicked";
 
 const char kOnSyncStateChanged[] = "syncFileSystem.onSyncStateChanged";
 const char kOnFileSynced[] = "syncFileSystem.onFileSynced";
 
 const char kOnAttachEventName[] = "mediaGalleriesPrivate.onDeviceAttached";
 const char kOnDetachEventName[] = "mediaGalleriesPrivate.onDeviceDetached";
+const char kOnGalleryChangedEventName[] =
+    "mediaGalleriesPrivate.onGalleryChanged";
 
 }  // namespace event_names
 
 }  // namespace extensions