<webview>: Add test coverage for deferred newwindow attachment.

chrome/renderer/resources/extensions/web_view.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.
 
 // This module implements Webview (<webview>) as a custom element that wraps a
 // BrowserPlugin object element. The object element is hidden within
 // the shadow DOM of the Webview element.
 
 var DocumentNatives = requireNative('document_natives');
 var GuestViewInternal =
@@ skipping 848 matching lines @@
   return params;
 };
 
 WebViewInternal.prototype.attachWindow = function(guestInstanceId,
                                                   isNewWindow) {
   this.guestInstanceId = guestInstanceId;
   var params = this.buildAttachParams(isNewWindow);
 
   if (!this.isPluginInRenderTree()) {
     this.deferredAttachState = {isNewWindow: isNewWindow};
-    return false;
+    return true;
   }
 
   this.deferredAttachState = null;
   return guestViewInternalNatives.AttachGuest(
       this.internalInstanceId,
       this.guestInstanceId,
       params);
 };
 
 // Registers browser plugin <object> custom element.
@@ skipping 153 matching lines @@
 };
 
 /**
  * Implemented when the experimental API is available.
  * @private
  */
 WebViewInternal.prototype.setupExperimentalContextMenus = function() {};
 
 exports.WebView = WebView;
 exports.WebViewInternal = WebViewInternal;