gpu/linux: create a child window to control resize and avoid flashes

ui/gl/gl_surface_glx.h

 // Copyright (c) 2012 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 UI_GL_GL_SURFACE_GLX_H_
 #define UI_GL_GL_SURFACE_GLX_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 58 matching lines @@
   NativeViewGLSurfaceGLX();
   virtual ~NativeViewGLSurfaceGLX();
 
  private:
   // The handle for the drawable to make current or swap.
   gfx::AcceleratedWidget GetDrawableHandle() const;
 
   // Window passed in at creation. Always valid.
   gfx::AcceleratedWidget parent_window_;
 
+  // Child window, used to control resizes so that they're in-order with GL.
+  gfx::AcceleratedWidget window_;
+
   void* config_;
   gfx::Size size_;
 
   scoped_ptr<VSyncProvider> vsync_provider_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeViewGLSurfaceGLX);
 };
 
 // A surface used to render to an offscreen pbuffer.
 class GL_EXPORT PbufferGLSurfaceGLX : public GLSurfaceGLX {
@@ skipping 16 matching lines @@
   gfx::Size size_;
   void* config_;
   XID pbuffer_;
 
   DISALLOW_COPY_AND_ASSIGN(PbufferGLSurfaceGLX);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_SURFACE_GLX_H_