GPUProcessor uses O3D command buffer service to render to a window....

o3d/command_buffer/service/win/d3d9/gapi_d3d9.h

 /*
  * Copyright 2009, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 36 matching lines @@
 namespace o3d {
 namespace command_buffer {
 
 // This class implements the GAPI interface for D3D9.
 class GAPID3D9 : public GAPIInterface {
  public:
   GAPID3D9();
   virtual ~GAPID3D9();
 
   void set_hwnd(HWND hwnd) { hwnd_ = hwnd; }
+  HWND hwnd() const { return hwnd_; }
 
   // Initializes the graphics context, bound to a window.
   // Returns:
   //   true if successful.
   virtual bool Initialize();
 
   // Destroys the graphics context.
   virtual void Destroy();
 
   // Implements the BeginFrame function for D3D9.
@@ skipping 356 matching lines @@
   ResourceMap<SamplerD3D9> samplers_;
   ResourceMap<RenderSurfaceD3D9> render_surfaces_;
   ResourceMap<RenderDepthStencilSurfaceD3D9> depth_surfaces_;
 };
 
 }  // namespace command_buffer
 }  // namespace o3d
 
 #endif  // O3D_COMMAND_BUFFER_SERVICE_WIN_D3D9_GAPI_D3D9_H_