Make GPU back-pressure work with remote CALayers

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"
 #include "ui/gl/gl_bindings.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();
+  IOSurfaceStorageProvider(ImageTransportSurfaceFBO* transport_surface);
   virtual ~IOSurfaceStorageProvider();
 
   // ImageTransportSurfaceFBO::StorageProvider implementation:
   virtual gfx::Size GetRoundedSize(gfx::Size size) OVERRIDE;
   virtual bool AllocateColorBufferStorage(
       CGLContextObj context, GLuint texture,
       gfx::Size pixel_size, float scale_factor) OVERRIDE;
   virtual void FreeColorBufferStorage() OVERRIDE;
   virtual uint64 GetSurfaceHandle() const OVERRIDE;
   virtual void WillSwapBuffers() OVERRIDE;
+  virtual void CanFreeSwappedBuffer() OVERRIDE;
 
  private:
+  ImageTransportSurfaceFBO* transport_surface_;
+
   base::ScopedCFTypeRef<IOSurfaceRef> io_surface_;
 
+  // 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_MAC_H_