Implement mediaGalleriesPrivate api to notify extensions about gallery changed events.

chrome/browser/extensions/api/media_galleries_private/media_galleries_private_api_factory.h

Index: chrome/browser/extensions/api/media_galleries_private/media_galleries_private_api_factory.h
diff --git a/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_api_factory.h b/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_api_factory.h
index 3df1704de957bf59e1b2491fe3c59ef528d7b051..ab22e34eab75dc4e0eee86fde434163faf5fae8b 100644
--- a/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_api_factory.h
+++ b/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_api_factory.h
@@ -8,16 +8,25 @@
 #include "base/memory/singleton.h"
 #include "chrome/browser/profiles/profile_keyed_service_factory.h"
 
+class Profile;
+
 namespace extensions {
+
 class MediaGalleriesPrivateAPI;
 
+// Singleton that associate MediaGalleriesPrivateAPI objects with Profiles.
 class MediaGalleriesPrivateAPIFactory : public ProfileKeyedServiceFactory {
  public:
+  // Returns the MediaGalleriesPrivateAPI for |profile|, creating it if
+  // it is not yet created.
+  static MediaGalleriesPrivateAPI* GetForProfile(Profile* profile);
+
   static MediaGalleriesPrivateAPIFactory* GetInstance();
 
  private:
   friend struct DefaultSingletonTraits<MediaGalleriesPrivateAPIFactory>;
 
+  // Use GetInstance().
   MediaGalleriesPrivateAPIFactory();
   virtual ~MediaGalleriesPrivateAPIFactory();
 
@@ -26,6 +35,8 @@ class MediaGalleriesPrivateAPIFactory : public ProfileKeyedServiceFactory {
       Profile* profile) const OVERRIDE;
   virtual bool ServiceIsCreatedWithProfile() const OVERRIDE;
   virtual bool ServiceIsNULLWhileTesting() const OVERRIDE;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaGalleriesPrivateAPIFactory);
 };
 
 }  // namespace extensions