Mac: Partially enable partial swap

content/common/gpu/image_transport_surface_iosurface_mac.h

 // Copyright 2014 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 CONTENT_COMMON_GPU_IMAGE_TRANSPORT_SURFACE_IOSURFACE_MAC_H_
 #define CONTENT_COMMON_GPU_IMAGE_TRANSPORT_SURFACE_IOSURFACE_MAC_H_
 
 #include <list>
 
 #include "content/common/gpu/image_transport_surface_fbo_mac.h"
 
 // Note that this must be included after gl_bindings.h to avoid conflicts.
 #include <OpenGL/CGLIOSurface.h>
 
 namespace content {
 
 // Allocate IOSurface-backed storage for an FBO image transport surface.
 class IOSurfaceStorageProvider
     : public ImageTransportSurfaceFBO::StorageProvider {
  public:
   IOSurfaceStorageProvider(ImageTransportSurfaceFBO* transport_surface);
   ~IOSurfaceStorageProvider() override;
 
   // ImageTransportSurfaceFBO::StorageProvider implementation:
   gfx::Size GetRoundedSize(gfx::Size size) override;
   bool AllocateColorBufferStorage(
       CGLContextObj context, const base::Closure& context_dirtied_callback,
       GLuint texture, gfx::Size pixel_size, float scale_factor) override;
   void FreeColorBufferStorage() override;
-  void SwapBuffers(const gfx::Size& size, float scale_factor) override;
+  void FrameSizeChanged(
+      const gfx::Size& pixel_size, float scale_factor) override;
+  void SwapBuffers() override;
   void WillWriteToBackbuffer() override;
   void DiscardBackbuffer() override;
   void SwapBuffersAckedByBrowser(bool disable_throttling) override;
 
  private:
   ImageTransportSurfaceFBO* transport_surface_;
 
   base::ScopedCFTypeRef<IOSurfaceRef> io_surface_;
+  gfx::Size frame_pixel_size_;
+  float frame_scale_factor_;
 
   // The list of IOSurfaces that have been sent to the browser process but have
   // not been opened in the browser process yet. This list should never have
   // more than one entry.
   std::list<base::ScopedCFTypeRef<IOSurfaceRef>> pending_swapped_surfaces_;
 
   // The id of |io_surface_| or 0 if that's NULL.
   IOSurfaceID io_surface_id_;
 
   DISALLOW_COPY_AND_ASSIGN(IOSurfaceStorageProvider);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GPU_IMAGE_TRANSPORT_SURFACE_IOSURFACE_MAC_H_