Never lock the Pepper proxy lock on the IO thread

ppapi/nacl_irt/ppapi_dispatcher.cc

 // Copyright 2014 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.
 
 #include "ppapi/nacl_irt/ppapi_dispatcher.h"
 
 #include <map>
 #include <set>
 
 #include "build/build_config.h"
@@ skipping 42 matching lines @@
       message_loop_(io_loop),
       shutdown_event_(shutdown_event),
       renderer_ipc_fd_(renderer_ipc_fd) {
 #if defined(IPC_MESSAGE_LOG_ENABLED)
   IPC::Logging::set_log_function_map(&g_log_function_mapping);
 #endif
 
   IPC::ChannelHandle channel_handle(
       "NaCl IPC", base::FileDescriptor(browser_ipc_fd, false));
 
+  proxy::PluginGlobals* globals = proxy::PluginGlobals::Get();
   // Delay initializing the SyncChannel until after we add filters. This
   // ensures that the filters won't miss any messages received by
   // the channel.
   channel_ =
       IPC::SyncChannel::Create(this, GetIPCMessageLoop(), GetShutdownEvent());
-  channel_->AddFilter(new proxy::PluginMessageFilter(
-      NULL, proxy::PluginGlobals::Get()->resource_reply_thread_registrar()));
+  scoped_refptr<ppapi::proxy::PluginMessageFilter> plugin_filter(
+      new ppapi::proxy::PluginMessageFilter(
+          NULL, globals->resource_reply_thread_registrar()));
+  channel_->AddFilter(plugin_filter.get());
+  globals->RegisterResourceMessageFilters(plugin_filter.get());
+
   channel_->AddFilter(
       new tracing::ChildTraceMessageFilter(message_loop_.get()));
   channel_->Init(channel_handle, IPC::Channel::MODE_SERVER, true);
 }
 
 base::MessageLoopProxy* PpapiDispatcher::GetIPCMessageLoop() {
   return message_loop_.get();
 }
 
 base::WaitableEvent* PpapiDispatcher::GetShutdownEvent() {
@@ skipping 137 matching lines @@
     NOTREACHED();
     return;
   }
   std::map<uint32, proxy::PluginDispatcher*>::iterator dispatcher =
       plugin_dispatchers_.find(id);
   if (dispatcher != plugin_dispatchers_.end())
     dispatcher->second->OnMessageReceived(msg);
 }
 
 }  // namespace ppapi