Make extensions developer mode adhere to policy

chrome/browser/resources/extensions/extensions.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.
 
 <include src="../../../../ui/webui/resources/js/cr/ui/focus_row.js">
 <include src="../../../../ui/webui/resources/js/cr/ui/focus_grid.js">
 <include src="../uber/uber_utils.js">
 <include src="drag_and_drop_handler.js">
 <include src="extension_code.js">
 <include src="extension_commands_overlay.js">
@@ skipping 178 matching lines @@
     update_: function(profileInfo) {
       // We only set the page to be loading if we haven't already finished an
       // initial load, because otherwise the updates are all incremental and
       // don't need to display the interstitial spinner.
       if (!this.hasLoaded_)
         this.setLoading_(true);
       webuiResponded = true;
 
       /** @const */
       var supervised = profileInfo.isSupervised;
+      var developerModeControlledByPolicy =
+          profileInfo.isDeveloperModeControlledByPolicy;
 
       var pageDiv = $('extension-settings');
       pageDiv.classList.toggle('profile-is-supervised', supervised);
       pageDiv.classList.toggle('showing-banner', supervised);
 
       var devControlsCheckbox = $('toggle-dev-on');
       devControlsCheckbox.checked = profileInfo.inDeveloperMode;
-      devControlsCheckbox.disabled = supervised;
+      devControlsCheckbox.disabled =
+          supervised || developerModeControlledByPolicy;
+
+      // This is necessary e.g. if developer mode is now disabled by policy
+      // but extension developer tools were visible.
+      this.updateDevControlsVisibility_(false);
+      this.updateDevToggleControlledIndicator_(developerModeControlledByPolicy);
 
       $('load-unpacked').disabled = !profileInfo.canLoadUnpacked;
       var extensionList = $('extension-settings-list');
       extensionList.updateExtensionsData(
           profileInfo.isIncognitoAvailable,
           profileInfo.appInfoDialogEnabled).then(function() {
         if (!this.hasLoaded_) {
           this.hasLoaded_ = true;
           this.setLoading_(false);
         }
         this.onExtensionCountChanged();
       }.bind(this));
     },
 
     /**
+     * Shows or hides the 'controlled by policy' indicator on the dev-toggle
+     * checkbox.
+     * @param {boolean} devModeControlledByPolicy true if the indicator
+     *     should be showing.
+     * @private
+     */
+    updateDevToggleControlledIndicator_: function(devModeControlledByPolicy) {
+      var controlledIndicator = document.querySelector(
+          '#dev-toggle .controlled-setting-indicator');
+
+      if (!(controlledIndicator instanceof cr.ui.ControlledIndicator))
+        cr.ui.ControlledIndicator.decorate(controlledIndicator);
+
+      // We control the visibility of the ControlledIndicator by setting or
+      // removing the 'controlled-by' attribute (see controlled_indicator.css).
+      var isVisible = controlledIndicator.getAttribute('controlled-by');
+      if (devModeControlledByPolicy && !isVisible) {
+        var controlledBy = 'policy';
+        controlledIndicator.setAttribute(
+           'controlled-by', controlledBy);
+        controlledIndicator.setAttribute(
+            'text' + controlledBy,
+            loadTimeData.getString('extensionControlledSettingPolicy'));
+      } else if (!devModeControlledByPolicy && isVisible) {
+        // This hides the element - see above.
+        controlledIndicator.removeAttribute('controlled-by');

[Andrew T Wilson (Slow), 2016/12/04 14:54:54]

BTW, are the checks for isVisible/!isVisible needed here? Can't we just
add/remove the attributes every time (isn't that action idempotent)?

[Devlin, 2016/12/04 16:07:11]

I requested it change from that.  I slightly prefer this for the clarity and
because it saves a small amount of work.  If you feel strongly, I won't object
to returning it to the original (unconditional setting).

[pmarko, 2016/12/07 16:12:11]

Acknowledged.

+      }
+    },
+
+    /**
      * Shows the loading spinner and hides elements that shouldn't be visible
      * while loading.
      * @param {boolean} isLoading
      * @private
      */
     setLoading_: function(isLoading) {
       document.documentElement.classList.toggle('loading', isLoading);
       $('loading-spinner').hidden = !isLoading;
       $('dev-controls').hidden = isLoading;
       this.updateDevControlsVisibility_(false);
@@ skipping 193 matching lines @@
 
   // Export
   return {
     ExtensionSettings: ExtensionSettings
   };
 });
 
 window.addEventListener('load', function(e) {
   extensions.ExtensionSettings.getInstance().initialize();
 });