Revert of Create GPU child window on new thread.

gpu/ipc/service/child_window_surface_win.h

 // 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.
 
 #ifndef GPU_IPC_SERVICE_CHILD_WINDOW_SURFACE_WIN_H_
 #define GPU_IPC_SERVICE_CHILD_WINDOW_SURFACE_WIN_H_
 
 #include "ui/gl/gl_surface_egl.h"
 
 #include <windows.h>
 
 namespace gpu {
 
 class GpuChannelManager;
-struct SharedData;
 
 class ChildWindowSurfaceWin : public gl::NativeViewGLSurfaceEGL {
  public:
   ChildWindowSurfaceWin(GpuChannelManager* manager, HWND parent_window);
 
   // GLSurface implementation.
   EGLConfig GetConfig() override;
   bool Resize(const gfx::Size& size,
               float scale_factor,
               bool has_alpha) override;
   bool InitializeNativeWindow() override;
   gfx::SwapResult SwapBuffers() override;
   gfx::SwapResult PostSubBuffer(int x, int y, int width, int height) override;
 
+  void InvalidateWindowRect(const gfx::Rect& rect);
+
  protected:
   ~ChildWindowSurfaceWin() override;
 
  private:
   void ClearInvalidContents();
 
-  // This member contains all the data that can be accessed from the main or
-  // window owner threads.
-  std::unique_ptr<SharedData> shared_data_;
   HWND parent_window_;
   GpuChannelManager* manager_;
+  gfx::Rect rect_to_clear_;
   bool alpha_;
   bool first_swap_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildWindowSurfaceWin);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_IPC_SERVICE_CHILD_WINDOW_SURFACE_WIN_H_