Turn on useUnfortunateSynchronousResizeMode.

content/renderer/resizing_mode_selector.h

 // Copyright 2013 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.
 
 #ifndef CONTENT_RENDERER_RESIZING_MODE_SELECTOR_H_
 #define CONTENT_RENDERER_RESIZING_MODE_SELECTOR_H_
 
 #include "base/basictypes.h"
 
 struct ViewMsg_Resize_Params;
 
 namespace content {
 
 class RenderWidget;
 
 // Enables switching between two modes of resizing:
 // 1) The "normal" (asynchronous) resizing, which involves sending messages to
 //    and receiving them from host; and
 // 2) The synchronous mode, which short-circuits the resizing logic to operate
 //    strictly inside renderer.
 // The latter is necessary to support a handful of layout tests that were
 // written with the expectation of a synchronous resize, and we're going to
 // eventually rewrite or remove all of them. See http://crbug.com/309760 for
 // details.
 class ResizingModeSelector {
  public:
   ResizingModeSelector();
-
+  bool NeverUsesSynchronousResize() const;
   bool ShouldAbortOnResize(RenderWidget* widget,
                            const ViewMsg_Resize_Params& params);
 
   void set_is_synchronous_mode(bool mode);
   bool is_synchronous_mode() const;
 
  private:
   bool is_synchronous_mode_;
 
   DISALLOW_COPY_AND_ASSIGN(ResizingModeSelector);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RESIZING_MODE_SELECTOR_H_