[MD History] Add UMA stats for switching views and the CBD button.

chrome/browser/resources/md_history/side_bar.js

Index: chrome/browser/resources/md_history/side_bar.js
diff --git a/chrome/browser/resources/md_history/side_bar.js b/chrome/browser/resources/md_history/side_bar.js
index 81eaf6a1a65d551c120415b059372133f7c166cc..c62dc53a36ea14cf2a59020c3d07bfa6a450ba96 100644
--- a/chrome/browser/resources/md_history/side_bar.js
+++ b/chrome/browser/resources/md_history/side_bar.js
@@ -2,19 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Histogram buckets for UMA tracking of menu usage.
-/** @const */ var MENU_HISTOGRAM = {
-  HISTORY: 0,
-  SYNCED_TABS: 1,
-  END: 2,  // Should always be last.
-};
-
 Polymer({
   is: 'history-side-bar',
 
   properties: {
     selectedPage:
-        {type: String, notify: true, observer: 'selectedPageChanged_'},
+        {type: String, notify: true},
 
     route: Object,
 
@@ -32,23 +25,6 @@ Polymer({
     this.fire('history-close-drawer');
   },
 
-  selectedPageChanged_: function(value, oldValue) {
-    if (!this.$.menu.selectedItem)
-      return;
-
-    var histogramValue = MENU_HISTOGRAM.END;
-    switch(this.$.menu.selectedItem.getAttribute('path')) {
-      case 'history':
-        histogramValue = MENU_HISTOGRAM.HISTORY;
-        break;
-      case 'syncedTabs':
-        histogramValue = MENU_HISTOGRAM.SYNCED_TABS;
-        break;
-    }
-    md_history.BrowserService.getInstance().recordHistogram(
-        ['History.SidebarMenuSelected', histogramValue, MENU_HISTOGRAM.END]);
-  },
-
   /**
    * Relocates the user to the clear browsing data section of the settings page.
    * @param {Event} e