[MediaRouter] Update MR-2-Extension's PostMessage to return boolean.

chrome/browser/media/router/media_router.mojom

Index: chrome/browser/media/router/media_router.mojom
diff --git a/chrome/browser/media/router/media_router.mojom b/chrome/browser/media/router/media_router.mojom
index e67b327f5571e0419906741eeae7448f81d9ac6e..d6fefd4ae6a0877307cb5cdd576100b48de0496d 100644
--- a/chrome/browser/media/router/media_router.mojom
+++ b/chrome/browser/media/router/media_router.mojom
@@ -96,7 +96,8 @@ interface MediaRouter {
 
   // Sends |message| with optional |extra_info_json| via the media route

[Kevin M, 2015/06/11 22:45:24]

extra_info_json is no more.

[haibinlu, 2015/06/11 23:05:22]

removed

   // |media_route_id|.
-  PostMessage(string media_route_id, string message);
+  // If the operation was sucessfull, |sent| is true; otherwise it is false.

[Kevin M, 2015/06/11 22:45:24]

extra 'l' in successful

[haibinlu, 2015/06/11 23:05:22]

Done.

+  SendMessage(string media_route_id, string message) => (bool sent);
 
   // Starts querying for sinks capable of displaying |media_source|.
   StartObservingMediaSinks(string media_source);