Add support for EXT_image_flush_external extension

ui/gl/gl_image_io_surface.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 UI_GL_GL_IMAGE_IO_SURFACE_H_
 #define UI_GL_GL_IMAGE_IO_SURFACE_H_
 
 #include <CoreVideo/CVPixelBuffer.h>
 #include <IOSurface/IOSurface.h>
 #include <stdint.h>
@@ skipping 56 matching lines @@
 
   // Whether checking IOSurfaceIsInUse() will actually provide a meaningful
   // signal about whether the Window Server is still using the IOSurface.
   bool CanCheckIOSurfaceIsInUse() const;
 
   static unsigned GetInternalFormatForTesting(gfx::BufferFormat format);
 
   // Downcasts from |image|. Returns |nullptr| on failure.
   static GLImageIOSurface* FromGLImage(GLImage* image);
 
+  void Flush() override {}

[reveman, 2016/07/11 18:59:06]

nit: move below ScheduleOverlayPlane

+
  protected:
   ~GLImageIOSurface() override;
 
  private:
   Type GetType() const override;
   class RGBConverter;
 
   const gfx::Size size_;
 
   // The "internalformat" exposed to the command buffer, which may not be
   // "internalformat" requested by the client.
   const unsigned internalformat_;
 
   // The "internalformat" requested by the client.
   const unsigned client_internalformat_;
 
   gfx::BufferFormat format_;
   base::ScopedCFTypeRef<IOSurfaceRef> io_surface_;
   base::ScopedCFTypeRef<CVPixelBufferRef> cv_pixel_buffer_;
   gfx::GenericSharedMemoryId io_surface_id_;
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(GLImageIOSurface);
 };
 
 }  // namespace gl
 
 #endif  // UI_GL_GL_IMAGE_IO_SURFACE_H_