webui: remove FocusManager.disableMouseFocusOnButtons().

chrome/browser/resources/extensions/extension_focus_manager.js

Index: chrome/browser/resources/extensions/extension_focus_manager.js
diff --git a/chrome/browser/resources/extensions/extension_focus_manager.js b/chrome/browser/resources/extensions/extension_focus_manager.js
index b2200245b6e03a56fcd94f939da2a4dfc7a3c836..377744caaeb0925b474ed5d303a9bf6a91a9534b 100644
--- a/chrome/browser/resources/extensions/extension_focus_manager.js
+++ b/chrome/browser/resources/extensions/extension_focus_manager.js
@@ -3,16 +3,16 @@
 // found in the LICENSE file.
 
 cr.define('extensions', function() {
-  var FocusManager = cr.ui.FocusManager;
-
-  function ExtensionFocusManager() {
-    FocusManager.disableMouseFocusOnButtons();
-  }
+  /**
+   * @constructor
+   * @extends {cr.ui.FocusManager}
+   */
+  function ExtensionFocusManager() {}
 
   cr.addSingletonGetter(ExtensionFocusManager);
 
   ExtensionFocusManager.prototype = {
-    __proto__: FocusManager.prototype,
+    __proto__: cr.ui.FocusManager.prototype,
 
     /** @override */
     getFocusParent: function() {