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

content/common/gpu/gpu_channel.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(OS_WIN)
 #include <windows.h>
 #endif
 
 #include "content/common/gpu/gpu_channel.h"
 
 #include "base/command_line.h"
+#include "base/debug/trace_event.h"
 #include "base/process_util.h"
 #include "base/string_util.h"
 #include "content/common/child_process.h"
 #include "content/common/content_client.h"
 #include "content/common/content_switches.h"
 #include "content/common/gpu/gpu_channel_manager.h"
 #include "content/common/gpu/gpu_messages.h"
 #include "content/common/gpu/gpu_video_service.h"
 #include "content/common/gpu/transport_texture.h"
 #include "ui/gfx/gl/gl_surface.h"
@@ skipping 222 matching lines @@
       parent_stub,
       size,
       disallowed_extensions_,
       init_params.allowed_extensions,
       init_params.attribs,
       parent_texture_id,
       *route_id,
       0, 0, watchdog_));
   router_.AddRoute(*route_id, stub.get());
   stubs_.AddWithID(stub.release(), *route_id);
+  TRACE_EVENT1("gpu", "GpuChannel::OnCreateOffscreenCommandBuffer",
+               "route_id", route_id);
 #else
   *route_id = MSG_ROUTING_NONE;
 #endif
 }
 
 void GpuChannel::OnDestroyCommandBuffer(int32 route_id) {
 #if defined(ENABLE_GPU)
+  TRACE_EVENT1("gpu", "GpuChannel::OnDestroyCommandBuffer",
+               "route_id", route_id);
   if (router_.ResolveRoute(route_id)) {
+    GpuCommandBufferStub* stub = stubs_.Lookup(route_id);
+    // In case the renderer is currently blocked waiting for a sync reply from
+    // the stub, allow the stub to clean up and unblock pending messages here:
+    if (stub != NULL)
+      stub->CommandBufferWasDestroyed();
     router_.RemoveRoute(route_id);
     stubs_.Remove(route_id);
   }
 #endif
 }
 
 void GpuChannel::OnCreateOffscreenSurface(const gfx::Size& size,
                                           int* route_id) {
   *route_id = MSG_ROUTING_NONE;
 
@@ skipping 96 matching lines @@
 
 #if defined(OS_POSIX)
 int GpuChannel::GetRendererFileDescriptor() {
   int fd = -1;
   if (channel_.get()) {
     fd = channel_->GetClientFileDescriptor();
   }
   return fd;
 }
 #endif  // defined(OS_POSIX)