<webview> + <extensionview>: Create a maybeHandleMutation call into attributes

extensions/renderer/resources/guest_view/extension_view_attributes.js

 // Copyright 2015 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.
 
 // This module implements the attributes of the <extensionview> tag.
 
 var GuestViewInternal =
     require('binding').Binding.create('guestViewInternal').generate();
 var ExtensionViewImpl = require('extensionView').ExtensionViewImpl;
 var ExtensionViewConstants =
@@ skipping 37 matching lines @@
       return this.getValue();
     }.bind(this),
     set: function(value) {
       this.setValue(value);
     }.bind(this),
     enumerable: true
   });
 };
 
 // Called when the attribute's value changes.
+ExtensionViewAttribute.prototype.maybeHandleMutation =
+    function(oldValue, newValue) {
+  if (this.ignoreMutation) {
+    return;
+  }
+
+  this.handleMutation(oldValue, newValue);
+}
+
+// Called when a change that isn't ignored occurs to the attribute's value.
 ExtensionViewAttribute.prototype.handleMutation =
     function(oldValue, newValue) {};
 
 // Attribute that handles the location and navigation of the extensionview.
 function SrcAttribute(extensionViewImpl) {
   ExtensionViewAttribute.call(this, ExtensionViewConstants.ATTRIBUTE_SRC,
                               extensionViewImpl);
   this.setupMutationObserver();
   this.beforeFirstNavigation = true;
 }
 
 SrcAttribute.prototype.__proto__ = ExtensionViewAttribute.prototype;
 
 SrcAttribute.prototype.setValueIgnoreMutation = function(value) {
   this.observer.takeRecords();
   this.ignoreMutation = true;
   this.extensionViewImpl.element.setAttribute(this.name, value || '');
   this.ignoreMutation = false;
 }
 
 SrcAttribute.prototype.handleMutation = function(oldValue, newValue) {
-  if (this.attributes[attributeName].ignoreMutation)
-    return;
-
   if (!newValue && oldValue) {
     this.setValueIgnoreMutation(oldValue);
     return;
   }
   this.parse();
 };
 
 SrcAttribute.prototype.setupMutationObserver =
     function() {
   this.observer = new MutationObserver(function(mutations) {
@@ skipping 35 matching lines @@
 };
 
 // -----------------------------------------------------------------------------
 
 // Sets up all of the extensionview attributes.
 ExtensionViewImpl.prototype.setupExtensionViewAttributes = function() {
   this.attributes = {};
   this.attributes[ExtensionViewConstants.ATTRIBUTE_SRC] =
       new SrcAttribute(this);
 };