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

chrome/browser/resources/media_router/media_router.js

 // 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 src="media_router_data.js">
 <include src="media_router_ui_interface.js">
 
 // Handles user events for the Media Router UI.
 cr.define('media_router', function() {
   'use strict';
 
   // The media-router-container element. Initialized after polymer is ready.
   var container = null;
 
   /**
    * Initializes the Media Router WebUI and requests initial media
    * router content, such as the media sink and media route lists.
    */
   function initialize() {
     media_router.browserApi.requestInitialData();
 
     container = $('media-router-container');
     media_router.ui.setContainer(container);
 
     container.addEventListener('close-button-click', onCloseDialogClick);
     container.addEventListener('close-route-click', onCloseRouteClick);
     container.addEventListener('create-route', onCreateRoute);
     container.addEventListener('issue-action-click', onIssueActionClick);
+    container.addEventListener('report-sink-count', onSinkCountReported);
   }
 
   /**
    * Closes the dialog.
    * Called when the user clicks the close button on the dialog.
    */
   function onCloseDialogClick() {
     media_router.browserApi.closeDialog();
   }
 
@@ skipping 34 matching lines @@
    * Called when the user requests to stop a media route.
    *
    * @param {{detail: {route: string}}} data
    * Parameters in |data|.detail:
    *   route - route ID.
    */
   function onCloseRouteClick(data) {
     media_router.browserApi.closeRoute(data.detail.route);
   }
 
+  /**
+   * Reports the current sink count.
+   * Called 3 seconds after the dialog is initially opened.
+   *
+   * @param {{detail: {sinkCount: number}}} data
+   * Parameters in |data|.detail:
+   *   sinkCount - the number of sinks.
+   */
+  function onSinkCountReported(data) {
+    media_router.browserApi.reportSinkCount(data.detail.sinkCount);
+  }
+
   return {
     initialize: initialize,
   };
 });
 
 window.addEventListener('load', media_router.initialize);