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

content/common/gpu/image_transport_surface.h

Index: content/common/gpu/image_transport_surface.h
diff --git a/content/common/gpu/image_transport_surface.h b/content/common/gpu/image_transport_surface.h
index 9e1a05cfc42d61ba29b150ecebdd50477b83cadd..8e5f38a77efe87b94cd1f72cc248e2be2ac2057a 100644
--- a/content/common/gpu/image_transport_surface.h
+++ b/content/common/gpu/image_transport_surface.h
@@ -30,6 +30,7 @@ struct GpuHostMsg_AcceleratedSurfaceNew_Params;
 struct GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params;
 struct GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params;
 struct GpuHostMsg_AcceleratedSurfaceRelease_Params;
+struct GpuHostMsg_AcceleratedSurfaceSuggestDiscard_Params;
 
 namespace gfx {
 class GLSurface;
@@ -67,6 +68,7 @@ class ImageTransportSurface {
   virtual void OnPostSubBufferACK() = 0;
   virtual void OnResizeViewACK() = 0;
   virtual void OnResize(gfx::Size size) = 0;
+  virtual void OnDiscardSurface(uint64 surface_id) = 0;
 
   // Creates the appropriate surface depending on the GL implementation.
   static scoped_refptr<gfx::GLSurface>
@@ -109,6 +111,8 @@ class ImageTransportHelper : public IPC::Channel::Listener {
       GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params params);
   void SendAcceleratedSurfaceRelease(
       GpuHostMsg_AcceleratedSurfaceRelease_Params params);
+  void SendAcceleratedSurfaceSuggestDiscard(
+      GpuHostMsg_AcceleratedSurfaceSuggestDiscard_Params params);
   void SendResizeView(const gfx::Size& size);
 
   // Whether or not we should execute more commands.
@@ -133,6 +137,7 @@ class ImageTransportHelper : public IPC::Channel::Listener {
   void OnBuffersSwappedACK();
   void OnPostSubBufferACK();
   void OnResizeViewACK();
+  void OnDiscardSurface(uint64 surface_id);
 
   // Backbuffer resize callback.
   void Resize(gfx::Size size);
@@ -173,6 +178,7 @@ class PassThroughImageTransportSurface
   virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
+  virtual void OnDiscardSurface(uint64 surface_id) OVERRIDE;
 
  protected:
   virtual ~PassThroughImageTransportSurface();