Media Galleries API: Fix MediaGalleriesPreferences finders race.

chrome/browser/media_galleries/media_file_system_registry.h

Index: chrome/browser/media_galleries/media_file_system_registry.h
diff --git a/chrome/browser/media_galleries/media_file_system_registry.h b/chrome/browser/media_galleries/media_file_system_registry.h
index 4c6b77716ed5b285632328819641dc7b7074563c..dbd873eeb10d541c14eb00c921133240b3793dd7 100644
--- a/chrome/browser/media_galleries/media_file_system_registry.h
+++ b/chrome/browser/media_galleries/media_file_system_registry.h
@@ -76,13 +76,9 @@ class MediaFileSystemRegistry
       const extensions::Extension* extension,
       const MediaFileSystemsCallback& callback);
 
-  // Returns the initialized media galleries preferences for the specified
-  // |profile|. This method should be used instead of calling
-  // MediaGalleriesPreferences directly because this method also ensures that
-  // currently attached removable devices are added to the preferences.
-  // Called on the UI thread.
-  // Note: Caller must ensure that the storage monitor is initialized before
-  // calling this method.
+  // Returns the media galleries preferences for the specified |profile|.
+  // Called on the UI thread. Caller is responsible for ensuring that the
+  // preferences are initialized before use.
   MediaGalleriesPreferences* GetPreferences(Profile* profile);
 
   // RemovableStorageObserver implementation.