Record NewTabPage.MostVisited histogram on Android.

chrome/browser/resources/ntp_android/ntp_android.js

 // Copyright (c) 2011 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.
 
 // File Description:
 //     Contains all the necessary functions for rendering the NTP on mobile
 //     devices.
 
 /**
  * The event type used to determine when a touch starts.
@@ skipping 925 matching lines @@
    */
   function setMostVisitedPages(data, hasBlacklistedUrls) {
     setNumberOfMostVisitedPages(data.length);
     // limit the number of most visited items to display
     if (isPhone() && data.length > 6) {
       data.splice(6, data.length - 6);
     } else if (isTablet() && data.length > 8) {
       data.splice(8, data.length - 8);
     }
 
+    data.forEach(function(item, index) {
+      item.mostVisitedIndex = index;
+    });
+
     if (equals(data, mostVisitedData_))
       return;
 
     var clickFunction = function(item) {
       chrome.send('openedMostVisited');
+      chrome.send('metricsHandler:recordInHistogram',
+          ['NewTabPage.MostVisited', item.mostVisitedIndex, 8]);
       window.location = item.url;
     };
     populateData(findList('most_visited'), SectionType.MOST_VISITED, data,
         makeMostVisitedItem, clickFunction);
     computeDynamicLayout();
 
     mostVisitedData_ = data;
   }
 
   /**
@@ skipping 236 matching lines @@
     if (contextMenuUrl != null) {
       switch (itemId) {
         case ContextMenuItemIds.BOOKMARK_OPEN_IN_NEW_TAB:
         case ContextMenuItemIds.BOOKMARK_OPEN_IN_INCOGNITO_TAB:
           chrome.send('openedBookmark');
           break;
 
         case ContextMenuItemIds.MOST_VISITED_OPEN_IN_NEW_TAB:
         case ContextMenuItemIds.MOST_VISITED_OPEN_IN_INCOGNITO_TAB:
           chrome.send('openedMostVisited');
+          if (contextMenuItem) {
+            chrome.send('metricsHandler:recordInHistogram',
+                ['NewTabPage.MostVisited',
+                 contextMenuItem.mostVisitedIndex,
+                 8]);
+          }
           break;
 
         case ContextMenuItemIds.RECENTLY_CLOSED_OPEN_IN_NEW_TAB:
         case ContextMenuItemIds.RECENTLY_CLOSED_OPEN_IN_INCOGNITO_TAB:
           chrome.send('openedRecentlyClosed');
           break;
       }
     }
 
     switch (itemId) {
@@ skipping 1506 matching lines @@
 // NTP Entry point.
 /////////////////////////////////////////////////////////////////////////////
 
 /*
  * Handles initializing the UI when the page has finished loading.
  */
 window.addEventListener('DOMContentLoaded', function(evt) {
   ntp.init();
   $('content-area').style.display = 'block';
 });