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

content/common/gpu/image_transport_surface.cc

Index: content/common/gpu/image_transport_surface.cc
diff --git a/content/common/gpu/image_transport_surface.cc b/content/common/gpu/image_transport_surface.cc
index 6601637950ff48ccb058d56cb2244dc98df90ee8..063cea49772ef9c65b4d89884edba4cb052ae2c4 100644
--- a/content/common/gpu/image_transport_surface.cc
+++ b/content/common/gpu/image_transport_surface.cc
@@ -99,6 +99,8 @@ bool ImageTransportHelper::OnMessageReceived(const IPC::Message& message) {
                         OnPostSubBufferACK)
     IPC_MESSAGE_HANDLER(AcceleratedSurfaceMsg_NewACK,
                         OnNewSurfaceACK)
+    IPC_MESSAGE_HANDLER(AcceleratedSurfaceMsg_ReleaseACK,
+                        OnReleaseSurfaceACK)
     IPC_MESSAGE_HANDLER(AcceleratedSurfaceMsg_ResizeViewACK, OnResizeViewACK);
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
@@ -182,6 +184,11 @@ void ImageTransportHelper::OnNewSurfaceACK(
   surface_->OnNewSurfaceACK(surface_handle, shm_handle);
 }
 
+void ImageTransportHelper::OnReleaseSurfaceACK(
+    uint64 surface_id, bool success) {
+  surface_->OnReleaseSurfaceACK(surface_id, success);
+}
+
 void ImageTransportHelper::OnResizeViewACK() {
   surface_->OnResizeViewACK();
 }
@@ -264,6 +271,10 @@ void PassThroughImageTransportSurface::OnNewSurfaceACK(
     uint64 surface_handle, TransportDIB::Handle shm_handle) {
 }
 
+void PassThroughImageTransportSurface::OnReleaseSurfaceACK(
+    uint64 surface_id, bool success) {
+}
+
 bool PassThroughImageTransportSurface::SwapBuffers() {
   bool result = gfx::GLSurfaceAdapter::SwapBuffers();