Split GpuProcessHost into GpuProcessHostUIShim, which runs on the UI...

chrome/browser/child_process_host.cc

Index: chrome/browser/child_process_host.cc
===================================================================
--- chrome/browser/child_process_host.cc	(revision 43024)
+++ chrome/browser/child_process_host.cc	(working copy)
@@ -80,7 +80,8 @@
 ChildProcessHost::~ChildProcessHost() {
   Singleton<ChildProcessList>::get()->remove(this);
 
-  resource_dispatcher_host_->CancelRequestsForProcess(id());
+  if (resource_dispatcher_host_)
+    resource_dispatcher_host_->CancelRequestsForProcess(id());
 }
 
 // static
@@ -217,9 +218,12 @@
 #endif
 
   bool msg_is_ok = true;
-  bool handled = host_->resource_dispatcher_host_->OnMessageReceived(
-      msg, host_, &msg_is_ok);
+  bool handled = false;
 
+  if (host_->resource_dispatcher_host_)
+    host_->resource_dispatcher_host_->OnMessageReceived(
+        msg, host_, &msg_is_ok);
+
   if (!handled) {
     if (msg.type() == PluginProcessHostMsg_ShutdownRequest::ID) {
       // Must remove the process from the list now, in case it gets used for a