Record NewTabPage.MostVisited histogram on Android.

chrome/browser/resources/ntp_android/ntp_android.js

Index: chrome/browser/resources/ntp_android/ntp_android.js
diff --git a/chrome/browser/resources/ntp_android/ntp_android.js b/chrome/browser/resources/ntp_android/ntp_android.js
index ad62da041f40a9ee09e7da6ae4773ab1205ab1a2..535f1984a64540674c06a7381ac5950f3854c826 100644
--- a/chrome/browser/resources/ntp_android/ntp_android.js
+++ b/chrome/browser/resources/ntp_android/ntp_android.js
@@ -943,11 +943,17 @@ cr.define('ntp', function() {
       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,
@@ -1204,6 +1210,12 @@ cr.define('ntp', function() {
         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: