Add support for EXT_image_flush_external extension

gpu/ipc/service/stream_texture_android.h

Index: gpu/ipc/service/stream_texture_android.h
diff --git a/gpu/ipc/service/stream_texture_android.h b/gpu/ipc/service/stream_texture_android.h
index 89c5172bc0c21398f7e5166096c3047e3c9422ed..1694711f1c0d04873a302612deec3b6d2d4a5354 100644
--- a/gpu/ipc/service/stream_texture_android.h
+++ b/gpu/ipc/service/stream_texture_android.h
@@ -81,6 +81,8 @@ class StreamTexture : public gpu::gles2::GLStreamTextureImage,
   void OnEstablishPeer(int32_t primary_id, int32_t secondary_id);
   void OnSetSize(const gfx::Size& size) { size_ = size; }
 
+  void Flush() override {}
+
   scoped_refptr<gl::SurfaceTexture> surface_texture_;
 
   // Current transform matrix of the surface texture.