Mac: Partially enable partial swap

content/common/gpu/image_transport_surface_fbo_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_FBO_MAC_H_
 #define CONTENT_COMMON_GPU_IMAGE_TRANSPORT_SURFACE_FBO_MAC_H_
 
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/scoped_ptr.h"
 #include "content/common/gpu/gpu_command_buffer_stub.h"
@@ skipping 23 matching lines @@
     // Allocate the storage for the color buffer. The specified context is
     // current, and there is a texture bound to GL_TEXTURE_RECTANGLE_ARB.
     virtual bool AllocateColorBufferStorage(
         CGLContextObj context, const base::Closure& context_dirtied_callback,
         GLuint texture, gfx::Size size, float scale_factor) = 0;
 
     // Free the storage allocated in the AllocateColorBufferStorage call. The
     // GL texture that was bound has already been deleted by the caller.
     virtual void FreeColorBufferStorage() = 0;
 
-    // Swap buffers and return the handle for the surface to send to the browser
-    // process to display.
-    virtual void SwapBuffers(const gfx::Size& size, float scale_factor) = 0;
+    // Called when the frame size has changed (the buffer may not have been
+    // reallocated, since its size may be rounded).
+    virtual void FrameSizeChanged(
+        const gfx::Size& pixel_size, float scale_factor) = 0;
+
+    // Swap buffers, or post sub-buffer.
+    virtual void SwapBuffers() = 0;
 
     // Indicate that the backbuffer will be written to.
     virtual void WillWriteToBackbuffer() = 0;
 
     // Indicate that the backbuffer has been discarded and should not be seen
     // again.
     virtual void DiscardBackbuffer() = 0;
 
     // Called once for every SwapBuffers call when the IPC for the present has
     // been processed by the browser. |disable_throttling| is set if the
@@ skipping 39 matching lines @@
   // GpuCommandBufferStub::DestructionObserver implementation.
   void OnWillDestroyStub() override;
 
  private:
   ~ImageTransportSurfaceFBO() override;
 
   void AdjustBufferAllocation();
   void DestroyFramebuffer();
   void AllocateOrResizeFramebuffer(
       const gfx::Size& pixel_size, float scale_factor);
+  bool SwapBuffersInternal();
 
   scoped_ptr<StorageProvider> storage_provider_;
 
   // Tracks the current buffer allocation state.
   bool backbuffer_suggested_allocation_;
   bool frontbuffer_suggested_allocation_;
 
   uint32 fbo_id_;
   GLuint texture_id_;
   GLuint depth_stencil_renderbuffer_id_;
@@ skipping 14 matching lines @@
   std::vector<ui::LatencyInfo> latency_info_;
 
   scoped_ptr<ImageTransportHelper> helper_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageTransportSurfaceFBO);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GPU_IMAGE_TRANSPORT_SURFACE_FBO_MAC_H_