Fix the mac hangup when force-compositing-mode is enabled

content/common/gpu/gpu_command_buffer_stub.cc

 // Copyright (c) 2011 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 "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/process_util.h"
 #include "base/shared_memory.h"
@@ skipping 375 matching lines @@
   params.route_id = route_id();
   params.swap_buffers_count = scheduler_->swap_buffers_count();
   gpu_channel_manager->Send(
       new GpuHostMsg_AcceleratedSurfaceBuffersSwapped(params));
 
   scheduler_->SetScheduled(false);
 }
 
 void GpuCommandBufferStub::AcceleratedSurfaceBuffersSwapped(
     uint64 swap_buffers_count) {
-  TRACE_EVENT0("gpu",
-               "GpuCommandBufferStub::AcceleratedSurfaceBuffersSwapped");
+  TRACE_EVENT1("gpu",
+               "GpuCommandBufferStub::AcceleratedSurfaceBuffersSwapped",
+               "frame", swap_buffers_count);
 
   // Multiple swapbuffers may get consolidated together into a single
   // AcceleratedSurfaceBuffersSwapped call. Since OnSwapBuffers expects to be
   // called one time for every swap, make up the difference here.
   uint64 delta = swap_buffers_count -
       scheduler_->acknowledged_swap_buffers_count();
-
   scheduler_->set_acknowledged_swap_buffers_count(swap_buffers_count);
 
-  for(uint64 i = 0; i < delta; i++)
+  for(uint64 i = 0; i < delta; i++) {
     OnSwapBuffers();
-
-  // Wake up the GpuScheduler to start doing work again.
-  scheduler_->SetScheduled(true);
+    // Wake up the GpuScheduler to start doing work again.
+    scheduler_->SetScheduled(true);
+  }
 }
 #endif  // defined(OS_MACOSX)
 
+void GpuCommandBufferStub::CommandBufferWasDestroyed() {
+  TRACE_EVENT0("gpu", "GpuCommandBufferStub::CommandBufferWasDestroyed");
+  // In case the renderer is currently blocked waiting for a sync reply from
+  // the stub, this method allows us to cleanup and unblock pending messages.
+  while (!scheduler_->IsScheduled())
+    scheduler_->SetScheduled(true);
+  // Handle any deferred messages now that the scheduler is scheduled.
+  HandleDeferredMessages();
+}
+
 void GpuCommandBufferStub::ResizeCallback(gfx::Size size) {
   if (handle_ == gfx::kNullPluginWindow) {
     scheduler_->decoder()->ResizeOffscreenFrameBuffer(size);
     scheduler_->decoder()->UpdateOffscreenFrameBufferSize();
   } else {
 #if defined(TOOLKIT_USES_GTK) && !defined(TOUCH_UI) || defined(OS_WIN)
     GpuChannelManager* gpu_channel_manager = channel_->gpu_channel_manager();
     gpu_channel_manager->Send(
         new GpuHostMsg_ResizeView(renderer_id_,
                                   render_view_id_,
@@ skipping 28 matching lines @@
       gfx::GLContext::LosesAllContextsOnContextLost()) {
     channel_->LoseAllContexts();
   } else {
     IPC::Message* msg = new GpuCommandBufferMsg_UpdateState(route_id_, state);
     msg->set_unblock(true);
     Send(msg);
   }
 }
 
 #endif  // defined(ENABLE_GPU)