[Media Router] Add P1 UMA metrics for Media Router.

chrome/browser/media/router/media_router_dialog_controller.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/media/router/media_router_dialog_controller.h"
 
+#include "base/metrics/histogram.h"
+#include "chrome/browser/media/router/media_router_metrics_enums.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
 
 #if defined(OS_ANDROID)
 #include "chrome/browser/media/android/router/media_router_dialog_controller_android.h"
 #else
 #include "chrome/browser/ui/webui/media_router/media_router_dialog_controller_impl.h"
 #endif
 
@@ skipping 61 matching lines @@
   // Check if the media router dialog exists for |initiator| and return if so.
   if (IsShowingMediaRouterDialog())
     return false;
 
   presentation_request_ = request.Pass();
   CreateMediaRouterDialog();
 
   // Show the initiator holding the existing media router dialog.
   ActivateInitiatorWebContents();
 
+  UMA_HISTOGRAM_ENUMERATION("MediaRouter.Icon.Click.Location",
+                            media_router::PAGE,
+                            media_router::TOTAL_COUNT);
+
   return true;
 }
 
 bool MediaRouterDialogController::ShowMediaRouterDialog() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   // Don't create dialog if it already exists.
   bool dialog_needs_creation = !IsShowingMediaRouterDialog();
   if (dialog_needs_creation)
     CreateMediaRouterDialog();
@@ skipping 16 matching lines @@
 MediaRouterDialogController::TakePresentationRequest() {
   return presentation_request_.Pass();
 }
 
 void MediaRouterDialogController::Reset() {
   initiator_observer_.reset();
   presentation_request_.reset();
 }
 
 }  // namespace media_router