PPAPI: Never re-enter JavaScript for PostMessage.

ppapi/proxy/dispatcher.cc

Index: ppapi/proxy/dispatcher.cc
diff --git a/ppapi/proxy/dispatcher.cc b/ppapi/proxy/dispatcher.cc
index 786c24d8b074380b127bf27202ceb66ba060ebb8..3c038a3906d8361d0623c62c74d88762a2c40483 100644
--- a/ppapi/proxy/dispatcher.cc
+++ b/ppapi/proxy/dispatcher.cc
@@ -47,11 +47,12 @@ InterfaceProxy* Dispatcher::GetInterfaceProxy(ApiID id) {
   return proxy;
 }
 
-void Dispatcher::AddIOThreadMessageFilter(IPC::MessageFilter* filter) {
+void Dispatcher::AddIOThreadMessageFilter(
+    scoped_refptr<IPC::MessageFilter> filter) {
   // Our filter is refcounted. The channel will call the destruct method on the
   // filter when the channel is done with it, so the corresponding Release()
   // happens there.
-  channel()->AddFilter(filter);
+  channel()->AddFilter(filter.get());
 }
 
 bool Dispatcher::OnMessageReceived(const IPC::Message& msg) {