[Media Router] Add UMA metrics for media route controller creation

chrome/browser/media/router/mojo/media_router_mojo_metrics.h

Index: chrome/browser/media/router/mojo/media_router_mojo_metrics.h
diff --git a/chrome/browser/media/router/mojo/media_router_mojo_metrics.h b/chrome/browser/media/router/mojo/media_router_mojo_metrics.h
index a9f79b383f32e702acfb23cb94e7bb260e9341da..481640b67d88978349f51c4c5c9c92f0ca759aa9 100644
--- a/chrome/browser/media/router/mojo/media_router_mojo_metrics.h
+++ b/chrome/browser/media/router/mojo/media_router_mojo_metrics.h
@@ -104,6 +104,10 @@ class MediaRouterMojoMetrics {
   static void RecordMediaRouteProviderTerminateRoute(
       RouteRequestResult::ResultCode result_code);
 
+  // Records whether the Media Route Provider succeeded or failed to create a
+  // controller for a media route.
+  static void RecordMediaRouteControllerCreationResult(bool success);
+
  private:
   FRIEND_TEST_ALL_PREFIXES(MediaRouterMojoMetricsTest,
                            TestGetMediaRouteProviderVersion);