Drop frontbuffers with ui-use-gpu-process, synchronized with browser, decoupled from backbuffer dro…

content/common/gpu/image_transport_surface_mac.cc

 // Copyright (c) 2012 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.
 
 #if defined(ENABLE_GPU)
 
 #include "content/common/gpu/image_transport_surface.h"
 
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 28 matching lines @@
   virtual unsigned int GetBackingFrameBufferObject() OVERRIDE;
   virtual void SetBufferAllocation(BufferAllocationState state) OVERRIDE;
 
  protected:
   // ImageTransportSurface implementation
   virtual void OnNewSurfaceACK(uint64 surface_handle,
                                TransportDIB::Handle shm_handle) OVERRIDE;
   virtual void OnBuffersSwappedACK() OVERRIDE;
   virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
+  virtual void OnDiscardSurface(uint64 surface_id) OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
 
  private:
   virtual ~IOSurfaceImageTransportSurface() OVERRIDE;
 
   void UnrefIOSurface();
   void CreateIOSurface();
 
   BufferAllocationState buffer_allocation_state_;
 
@@ skipping 173 matching lines @@
 void IOSurfaceImageTransportSurface::OnNewSurfaceACK(
     uint64 surface_handle,
     TransportDIB::Handle /* shm_handle */) {
   NOTREACHED();
 }
 
 void IOSurfaceImageTransportSurface::OnResizeViewACK() {
   NOTREACHED();
 }
 
+void IOSurfaceImageTransportSurface::OnDiscardSurface(uint64 surface_id) {
+}
+
 void IOSurfaceImageTransportSurface::OnResize(gfx::Size size) {
   // Caching |context_| from OnMakeCurrent. It should still be current.
   DCHECK(context_->IsCurrent(this));
 
   size_ = size;
 
   CreateIOSurface();
 }
 
 void IOSurfaceImageTransportSurface::UnrefIOSurface() {
@@ skipping 114 matching lines @@
       NOTREACHED();
       return NULL;
   }
   if (surface->Initialize())
     return surface;
   else
     return NULL;
 }
 
 #endif  // defined(USE_GPU)