[MD Bookmarks] Refactor focus ring hiding.

chrome/browser/resources/md_bookmarks/dialog_focus_manager.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.
 
 cr.define('bookmarks', function() {
   /**
    * Manages focus restoration for modal dialogs. After the final dialog in a
    * stack is closed, restores focus to the element which was focused when the
    * first dialog was opened.
    * @constructor
    */
   function DialogFocusManager() {
     /** @private {HTMLElement} */
     this.previousFocusElement_ = null;
 
-    /** @private {boolean} */
-    this.previousMouseFocus_ = false;
-
     /** @private {Set<HTMLDialogElement>} */
     this.dialogs_ = new Set();
   }
 
   DialogFocusManager.prototype = {
     /**
      * @param {HTMLDialogElement} dialog
      * @param {function()=} showFn
      */
     showDialog: function(dialog, showFn) {
@@ skipping 14 matching lines @@
         dialog.addEventListener('close', this.getCloseListener_(dialog));
         this.dialogs_.add(dialog);
       }
 
       showFn();
     },
 
     /** @private */
     updatePreviousFocus_: function() {
       this.previousFocusElement_ = this.getFocusedElement_();
-      this.previousMouseFocus_ = bookmarks.MouseFocusBehavior.isMouseFocused(
-          this.previousFocusElement_);
     },
 
     /**
      * @return {HTMLElement}
      * @private
      */
     getFocusedElement_: function() {
       var focus = document.activeElement;
       while (focus.root && focus.root.activeElement)
         focus = focus.root.activeElement;
 
       return focus;
     },
 
     /**
      * @param {HTMLDialogElement} dialog
      * @return {function(Event)}
      * @private
      */
     getCloseListener_: function(dialog) {
       var closeListener = function(e) {
         // If the dialog is open, then it got reshown immediately and we
         // shouldn't clear it until it is closed again.
         if (dialog.open)
           return;
 
         assert(this.dialogs_.delete(dialog));
         // Focus the originally focused element if there are no more dialogs.
-        if (!this.dialogs_.size) {
+        if (!this.dialogs_.size)
           this.previousFocusElement_.focus();
-          if (this.previousMouseFocus_) {
-            bookmarks.MouseFocusBehavior.addMouseFocusClass(
-                this.previousFocusElement_);
-          }
-        }
+
         dialog.removeEventListener('close', closeListener);
       }.bind(this);
 
       return closeListener;
     },
   };
 
   cr.addSingletonGetter(DialogFocusManager);
 
   return {
     DialogFocusManager: DialogFocusManager,
   };
 });