MD Settings: About page, implementing channel switcher dialog.

chrome/browser/resources/settings/about_page/about_page.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.
 
 /**
  * @fileoverview 'settings-about-page' contains version and OS related
  * information.
  */
 Polymer({
   is: 'settings-about-page',
@@ skipping 184 matching lines @@
   },
 
 <if expr="chromeos">
   /**
    * @return {boolean}
    * @private
    */
   isTargetChannelMoreStable_: function() {
     assert(this.currentChannel_.length > 0);
     assert(this.targetChannel_.length > 0);
-
-    // List of channels in increasing stability order.
-    var channelList = [
-      BrowserChannel.DEV,
-      BrowserChannel.BETA,
-      BrowserChannel.STABLE,
-    ];
-    var currentIndex = channelList.indexOf(this.currentChannel_);
-    var targetIndex = channelList.indexOf(this.targetChannel_);
-    return currentIndex < targetIndex;
+    return settings.isTargetChannelMoreStable(
+        this.currentChannel_, this.targetChannel_);
   },
 
   /** @private */
   onDetailedBuildInfoTap_: function() {
     var animatedPages = /** @type {!SettingsAnimatedPagesElement} */ (
         this.$.pages);
     animatedPages.setSubpageChain(['detailed-build-info']);
   },
 
   /** @private */
@@ skipping 34 matching lines @@
   },
 </if>
 
 <if expr="_google_chrome">
   /** @private */
   onReportIssueTap_: function() {
     this.browserProxy_.openFeedbackDialog();
   },
 </if>
 });