Add support for EXT_image_flush_external extension

gpu/command_buffer/tests/texture_image_factory.cc

 // Copyright 2016 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.
 
 #include "gpu/command_buffer/tests/texture_image_factory.h"
 
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_image.h"
 
 namespace gpu {
@@ skipping 26 matching lines @@
                             int z_order,
                             gfx::OverlayTransform transform,
                             const gfx::Rect& bounds_rect,
                             const gfx::RectF& crop_rect) override {
     return false;
   }
 
   void OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd,
                     uint64_t process_tracing_id,
                     const std::string& dump_name) override {}
+  void Flush() override {}
 
  private:
   ~TextureImage() override {}
   gfx::Size size_;
 };
 
 scoped_refptr<gl::GLImage> TextureImageFactory::CreateImageForGpuMemoryBuffer(
     const gfx::GpuMemoryBufferHandle& handle,
     const gfx::Size& size,
     gfx::BufferFormat format,
@@ skipping 15 matching lines @@
 
 bool TextureImageFactory::SupportsFormatRGB() {
   return false;
 }
 
 void TextureImageFactory::SetRequiredTextureType(unsigned type) {
   required_texture_type_ = type;
 }
 
 }  // namespace gpu