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

content/common/gpu/gpu_channel.cc

Index: content/common/gpu/gpu_channel.cc
diff --git a/content/common/gpu/gpu_channel.cc b/content/common/gpu/gpu_channel.cc
index 72d822b999911dfbfb59d6d11bfde42e1a62cb31..85333800260bdf9e95729709a1380e783807b63d 100644
--- a/content/common/gpu/gpu_channel.cc
+++ b/content/common/gpu/gpu_channel.cc
@@ -9,6 +9,7 @@
 #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"
@@ -251,6 +252,8 @@ void GpuChannel::OnCreateOffscreenCommandBuffer(
       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
@@ -258,7 +261,12 @@ void GpuChannel::OnCreateOffscreenCommandBuffer(
 
 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);
+    if (stub != NULL)
+      stub->CommandBufferWasDestroyed();

[jbates, 2011/06/07 16:47:52]

If the IPC route is removed, unblock the stub so that it can reply to any
pending calls from the renderer.

     router_.RemoveRoute(route_id);
     stubs_.Remove(route_id);
   }