Implement accessibility support for CSS-transformed iframes.

content/browser/frame_host/render_widget_host_view_child_frame.cc

 // 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.
 
 #include "content/browser/frame_host/render_widget_host_view_child_frame.h"
 
 #include <algorithm>
 #include <utility>
 #include <vector>
 
@@ skipping 553 matching lines @@
   return BrowserAccessibilityManager::Create(
       BrowserAccessibilityManager::GetEmptyDocument(), delegate);
 }
 
 void RenderWidgetHostViewChildFrame::ClearCompositorSurfaceIfNecessary() {
   if (surface_factory_ && !surface_id_.is_null())
     surface_factory_->Destroy(surface_id_);
   surface_id_ = cc::SurfaceId();
 }
 
+bool RenderWidgetHostViewChildFrame::IsChildFrameForTesting() const {
+  return true;
+}
+
 cc::SurfaceId RenderWidgetHostViewChildFrame::SurfaceIdForTesting() const {
   return surface_id_;
 };
 
 }  // namespace content