GuestView: Use computed size if getBoundingClientRect() size is unavailable.

extensions/renderer/resources/guest_view/guest_view_container.js

 // Copyright 2014 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 shared functionality for different guestview
 // containers, such as web_view, app_view, etc.
 
 var DocumentNatives = requireNative('document_natives');
 var GuestView = require('guestView').GuestView;
 var GuestViewInternalNatives = requireNative('guest_view_internal');
@@ skipping 139 matching lines @@
   this.dispatchEvent(resizeEvent);
 
   if (!this.guest.getId())
     return;
   this.guest.setSize({normal: {width: newWidth, height: newHeight}});
 };
 
 GuestViewContainer.prototype.buildParams = function() {
   var params = this.buildContainerParams();
   params['instanceId'] = this.viewInstanceId;
+  // When the GuestViewContainer is not participating in layout (display:none)
+  // then getBoundingClientRect() would report a width and height of 0.
+  // However, in the case where the GuestViewContainer has a fixed size we can
+  // use that value to initially size the guest so as to avoid a relayout of the
+  // on display:block.
+  var css = window.getComputedStyle(this.element, null);
   var elementRect = this.element.getBoundingClientRect();
-  params['elementWidth'] = parseInt(elementRect.width);
-  params['elementHeight'] = parseInt(elementRect.height);
+  params['elementWidth'] = parseInt(elementRect.width) ||
+      parseInt(css.getPropertyValue('width'));
+  params['elementHeight'] = parseInt(elementRect.height) ||
+      parseInt(css.getPropertyValue('height'));
   return params;
 };
 
 GuestViewContainer.prototype.dispatchEvent = function(event) {
   return this.element.dispatchEvent(event);
 }
 
 // Implemented by the specific view type, if needed.
 GuestViewContainer.prototype.buildContainerParams = function() { return {}; };
 GuestViewContainer.prototype.onElementAttached = function() {};
@@ skipping 89 matching lines @@
   // Delete the callbacks so developers cannot call them and produce unexpected
   // behavior.
   delete proto.createdCallback;
   delete proto.attachedCallback;
   delete proto.detachedCallback;
   delete proto.attributeChangedCallback;
 }
 
 // Exports.
 exports.GuestViewContainer = GuestViewContainer;