[Sync] Updating HistoryPage.OtherDevicesMenu metric to capture presence of foreign data.

chrome/browser/resources/history/other_devices.js

 // Copyright (c) 2013 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.
 
 /**
  * @fileoverview The section of the history page that shows tabs from sessions
                  on other devices.
  */
 
 ///////////////////////////////////////////////////////////////////////////////
 // Globals:
 /** @const */ var MAX_NUM_COLUMNS = 3;
 /** @const */ var NB_ENTRIES_FIRST_ROW_COLUMN = 6;
 /** @const */ var NB_ENTRIES_OTHER_ROWS_COLUMN = 0;
 
 // Histogram buckets for UMA tracking of menu usage.
 /** @const */ var HISTOGRAM_EVENT = {
   INITIALIZED: 0,
   SHOW_MENU: 1,
   LINK_CLICKED: 2,
   LINK_RIGHT_CLICKED: 3,
   SESSION_NAME_RIGHT_CLICKED: 4,
   SHOW_SESSION_MENU: 5,
   COLLAPSE_SESSION: 6,
   EXPAND_SESSION: 7,
   OPEN_ALL: 8,
-  LIMIT: 9  // Should always be the last one.
+  HAS_FOREIGN_DATA: 9,
+  LIMIT: 10  // Should always be the last one.
 };
 
 /**
  * Record an event in the UMA histogram.
  * @param {number} eventId The id of the event to be recorded.
  * @private
  */
 function recordUmaEvent_(eventId) {
   chrome.send('metricsHandler:recordInHistogram',
       ['HistoryPage.OtherDevicesMenu', eventId, HISTOGRAM_EVENT.LIMIT]);
@@ skipping 308 matching lines @@
  * Functions and state for populating the page with HTML.
  * @constructor
  */
 function DevicesView() {
   this.devices_ = [];  // List of individual devices.
   this.resultDiv_ = $('other-devices');
   this.searchText_ = '';
   this.rowHeights_ = [NB_ENTRIES_FIRST_ROW_COLUMN];
   this.focusGrids_ = [];
   this.updateSignInState(loadTimeData.getBoolean('isUserSignedIn'));
+  this.hasSeenForeignData_ = false;
   recordUmaEvent_(HISTOGRAM_EVENT.INITIALIZED);
 }
 
 // DevicesView, public: -------------------------------------------------------
 
 /**
  * Updates our sign in state by clearing the view is not signed in or sending
  * a request to get the data to display otherwise.
  * @param {boolean} signedIn Whether the user is signed in or not.
  */
 DevicesView.prototype.updateSignInState = function(signedIn) {
   if (signedIn)
     chrome.send('getForeignSessions');
   else
     this.clearDOM();
 };
 
 /**
  * Resets the view sessions.
  * @param {Object} sessionList The sessions to add.
  */
 DevicesView.prototype.setSessionList = function(sessionList) {
   this.devices_ = [];
   for (var i = 0; i < sessionList.length; i++)
     this.devices_.push(new Device(sessionList[i], this));
   this.displayResults_();
+
+  // This metric should only be emitted if we see foreign data, and it should
+  // only be emitted once per page refresh. Flip flag to remember because this
+  // method is called upon any update.
+  if (!this.hasSeenForeignData_ && sessionList.length > 0) {
+    this.hasSeenForeignData_ = true;
+    recordUmaEvent_(HISTOGRAM_EVENT.HAS_FOREIGN_DATA);
+  }
 };
 
 
 /**
  * Sets the current search text.
  * @param {string} searchText The text to search.
  */
 DevicesView.prototype.setSearchText = function(searchText) {
   if (this.searchText_ != searchText) {
     this.searchText_ = searchText;
@@ skipping 162 matching lines @@
     devicesView.setSearchText($('search-field').value);
   };
   $('search-field').addEventListener('search', doSearch);
   $('search-button').addEventListener('click', doSearch);
 
   chrome.send('otherDevicesInitialized');
 }
 
 // Add handlers to HTML elements.
 document.addEventListener('DOMContentLoaded', load);