chromeos: Avoid NOTREACHED for MD settings power page.

chrome/browser/resources/settings/device_page/power.js

 // Copyright 2017 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-power' is the settings subpage for power settings.
  */
 
 Polymer({
@@ skipping 49 matching lines @@
   /** @override */
   ready: function() {
     // enablePowerSettings comes from loadTimeData, so it will always be set
     // before attached() is called.
     if (!this.enablePowerSettings)
       settings.navigateToPreviousRoute();
   },
 
   /** @override */
   attached: function() {
+    // Even when the row is hidden, the element can still be attached via
+    // search.
+    if (!this.enablePowerSettings)
+      return;
+
     this.addWebUIListener(
         'battery-status-changed', this.set.bind(this, 'batteryStatus_'));
     this.addWebUIListener(
         'power-sources-changed', this.powerSourcesChanged_.bind(this));
     settings.DevicePageBrowserProxyImpl.getInstance().updatePowerStatus();

[Dan Beam, 2017/03/15 00:30:58]

i think you only want to wrap this line, but i'm not sure

[Daniel Erat, 2017/03/15 00:33:44]

hopefully one of the other reviewers will have a strong opinion about this,
because i don't. :-)

[michaelpg, 2017/03/15 01:13:18]

Nah, we should return early. Hopefully the comment in ready() helps. If
!enablePowerSettings, there shouldn't be any updates to listen to.

But that's another reason we shouldn't let this get attached in the first place.

   },
 
   /**
    * @param {!Array<!settings.PowerSource>|undefined} powerSources
    * @param {boolean} calculating
    * @return {string} The primary label for the power source row.
    * @private
    */
   computePowerSourceLabel_: function(powerSources, calculating) {
     return this.i18n(
@@ skipping 49 matching lines @@
   /**
    * @param {*} lhs
    * @param {*} rhs
    * @return {boolean}
    * @private
    */
   isEqual_: function(lhs, rhs) {
     return lhs === rhs;
   },
 });