Disable wallpaper button in Guest mode settings

chrome/browser/resources/options/browser_options.js

 // Copyright (c) 2012 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.
 
 cr.exportPath('options');
 
 /**
  * @typedef {{actionLinkText: (string|undefined),
  *            hasError: (boolean|undefined),
  *            hasUnrecoverableError: (boolean|undefined),
@@ skipping 1475 matching lines @@
         picture.src = 'chrome://userimage/' + this.username_ + '?id=' +
             Date.now();
       }
     },
 
     /**
      * @param {boolean} managed
      */
     setWallpaperManaged_: function(managed) {
       var button = $('set-wallpaper');
-      button.disabled = !!managed;
+      button.disabled |= !!managed;

[stevenjb, 2014/09/24 16:15:23]

nit: Actually, I think that in general this kind of thing is more clear as:
if (managed)
  button.disabled = true;
But that is really just a personal preference.

[michaelpg, 2014/09/24 22:29:23]

+dbeam@

Actually it looks like this can be called again, if the policy changes after the
page has loaded. We shouldn't enable the button if it's already been disabled by
UIAccountTweaks. I've added a helper function there I'd like Dan to take a look
at. I think some other controls should migrate to that function, too.

[Dan Beam, 2014/09/29 18:52:18]

why are we doing !! if |managed| should already be a boolean?

[Dan Beam, 2014/09/29 18:52:18]

any version including:

  button.disabled = button.disabled || managed;

is fine by me.  no particular preference here.  i'd say out of all the versions,
stevenjb@'s is probably the easiest to read, but we do (in general) prefer to
hit the same codepaths when possible (e.g. instead of if/else => ternary).

 
       // Create a synthetic pref change event decorated as
       // CoreOptionsHandler::CreateValueForPref() does.
       var event = new Event('wallpaper');
       if (managed)
         event.value = { controlledBy: 'policy' };
       else
         event.value = {};

[Dan Beam, 2014/09/29 18:52:18]

for example:

  event.value = managed ? {controlledBy: 'policy'} : {};

or

  event.value = {};
  if (managed)
    event.value.controlledBy = 'policy';

both seem mildly better

       $('wallpaper-indicator').handlePrefChange(event);
     },
 
     /**
      * Handle the 'add device' button click.
      * @private
      */
     handleAddBluetoothDevice_: function() {
       chrome.send('findBluetoothDevices');
       PageManager.showPageByName('bluetooth', false);
@@ skipping 521 matching lines @@
       }
       button.textContent = loadTimeData.getString(strId);
     };
   }
 
   // Export
   return {
     BrowserOptions: BrowserOptions
   };
 });