Store Media gallery permissions in extension prefs.

chrome/browser/media_gallery/media_galleries_preferences.h

Index: chrome/browser/media_gallery/media_galleries_preferences.h
diff --git a/chrome/browser/media_gallery/media_galleries_preferences.h b/chrome/browser/media_gallery/media_galleries_preferences.h
index 495501f9fd4705acfe49e4f963b5932ef4d1abef..076606ec792be90e2f2f6a065ee8929bbd53c501 100644
--- a/chrome/browser/media_gallery/media_galleries_preferences.h
+++ b/chrome/browser/media_gallery/media_galleries_preferences.h
@@ -13,12 +13,19 @@
 #include "base/string16.h"
 #include "chrome/browser/profiles/profile_keyed_service.h"
 
+class PrefService;
+class Profile;
+
 namespace base {
 class DictionaryValue;
 }
 
-class PrefService;
-class Profile;
+typedef uint64 MediaGalleryPrefId;
+
+struct MediaGalleryPermission {
+  MediaGalleryPrefId pref_id;
+  bool has_permission;
+};
 
 struct MediaGallery {
   MediaGallery();