[Media Router] Add UMA metrics for Media Router Dialog WebUI performance.

chrome/browser/media/router/media_router_metrics.cc

Index: chrome/browser/media/router/media_router_metrics.cc
diff --git a/chrome/browser/media/router/media_router_metrics.cc b/chrome/browser/media/router/media_router_metrics.cc
index ac317e22a3b9b5836724628089bae11c56f6f7ca..f20fe78da4eb720ed7eed7c75841f4c0b95a42fa 100644
--- a/chrome/browser/media/router/media_router_metrics.cc
+++ b/chrome/browser/media/router/media_router_metrics.cc
@@ -26,4 +26,18 @@ void MediaRouterMetrics::RecordMediaRouteProviderWakeReason(
       static_cast<int>(MediaRouteProviderWakeReason::TOTAL_COUNT));
 }
 
+// static
+void MediaRouterMetrics::RecordMediaRouterDialogInitialPaint(
+    const base::TimeDelta& delta) {
+  UMA_HISTOGRAM_TIMES("MediaRouter.Ui.Dialog.InitialPaint",
+                      delta);
+}
+
+// static
+void MediaRouterMetrics::RecordMediaRouterDialogInitializedWithData(
+    const base::TimeDelta& delta) {
+  UMA_HISTOGRAM_TIMES("MediaRouter.Ui.Dialog.InitializedWithData",
+                      delta);
+}
+
 }  // namespace media_router