[MD History] Copy stats from the old history page.

chrome/browser/resources/md_history/synced_device_manager.js

 // Copyright 2016 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.
 
 /**
  * @typedef {{device: string,
  *           lastUpdateTime: string,
  *           separatorIndexes: !Array<number>,
  *           timestamp: number,
  *           tabs: !Array<!ForeignSessionTab>,
@@ skipping 36 matching lines @@
     /** @private */
     guestSession_: {
       type: Boolean,
       value: loadTimeData.getBoolean('isGuestSession'),
     },
 
     /** @private */
     fetchingSyncedTabs_: {
       type: Boolean,
       value: false,
-    }
+    },
+
+    hasSeenForeignData_: Boolean,
   },
 
   listeners: {
     'toggle-menu': 'onToggleMenu_',
   },
 
   /** @override */
   attached: function() {
     // Update the sign in state.
     chrome.send('otherDevicesInitialized');
+    md_history.BrowserService.getInstance().recordHistogram(
+        SYNCED_TABS_HISTOGRAM_NAME, SyncedTabsHistogram.INITIALIZED,
+        SyncedTabsHistogram.LIMIT);
   },
 
   /**
    * @param {!ForeignSession} session
    * @return {!ForeignDeviceInternal}
    */
   createInternalDevice_: function(session) {
     var tabs = [];
     var separatorIndexes = [];
     for (var i = 0; i < session.windows.length; i++) {
@@ skipping 39 matching lines @@
   },
 
   onToggleMenu_: function(e) {
     this.$.menu.get().then(function(menu) {
       menu.toggleMenu(e.detail.target, e.detail.tag);
     });
   },
 
   onOpenAllTap_: function() {
     var menu = assert(this.$.menu.getIfExists());
-    md_history.BrowserService.getInstance().openForeignSessionAllTabs(
+    var browserService = md_history.BrowserService.getInstance();
+    browserService.recordHistogram(
+        SYNCED_TABS_HISTOGRAM_NAME, SyncedTabsHistogram.OPEN_ALL,
+        SyncedTabsHistogram.LIMIT);
+    browserService.openForeignSessionAllTabs(
         menu.itemData);
     menu.closeMenu();
   },
 
   onDeleteSessionTap_: function() {
     var menu = assert(this.$.menu.getIfExists());
-    md_history.BrowserService.getInstance().deleteForeignSession(
-        menu.itemData);
+    var browserService = md_history.BrowserService.getInstance();
+    browserService.recordHistogram(
+        SYNCED_TABS_HISTOGRAM_NAME, SyncedTabsHistogram.HIDE_FOR_NOW,
+        SyncedTabsHistogram.LIMIT);
+    browserService.deleteForeignSession(menu.itemData);
     menu.closeMenu();
   },
 
   /** @private */
   clearDisplayedSyncedDevices_: function() {
     this.syncedDevices_ = [];
   },
 
   /**
    * Decide whether or not should display no synced tabs message.
@@ skipping 45 matching lines @@
    * about updating individual tabs rather than replacing whole sessions, but
    * this approach seems to have acceptable performance.
    * @param {?Array<!ForeignSession>} sessionList
    */
   updateSyncedDevices: function(sessionList) {
     this.fetchingSyncedTabs_ = false;
 
     if (!sessionList)
       return;
 
+    if (sessionList.length > 0 && !this.hasSeenForeignData_) {
+      this.hasSeenForeignData_ = true;
+      md_history.BrowserService.getInstance().recordHistogram(
+        SYNCED_TABS_HISTOGRAM_NAME, SyncedTabsHistogram.HAS_FOREIGN_DATA,
+        SyncedTabsHistogram.LIMIT);
+    }
+
     // First, update any existing devices that have changed.
     var updateCount = Math.min(sessionList.length, this.syncedDevices_.length);
     for (var i = 0; i < updateCount; i++) {
       var oldDevice = this.syncedDevices_[i];
       if (oldDevice.tag != sessionList[i].tag ||
           oldDevice.timestamp != sessionList[i].timestamp) {
         this.splice(
             'syncedDevices_', i, 1, this.createInternalDevice_(sessionList[i]));
       }
     }
@@ skipping 29 matching lines @@
     // User signed in, show the loading message when querying for synced
     // devices.
     this.fetchingSyncedTabs_ = true;
   },
 
   searchTermChanged: function(searchTerm) {
     this.clearDisplayedSyncedDevices_();
     this.updateSyncedDevices(this.sessionList);
   }
 });