Never lock the Pepper proxy lock on the IO thread

ppapi/proxy/resource_reply_thread_registrar.cc

 // Copyright 2013 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/proxy/resource_reply_thread_registrar.h"
 
 #include "base/logging.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "ipc/ipc_message.h"
 #include "ppapi/proxy/resource_message_params.h"
@@ skipping 32 matching lines @@
 
     map_[resource][sequence_number] = reply_thread;
   }
 }
 
 void ResourceReplyThreadRegistrar::Unregister(PP_Resource resource) {
   base::AutoLock auto_lock(lock_);
   map_.erase(resource);
 }
 
-void ResourceReplyThreadRegistrar::HandleOnIOThread(uint32 nested_msg_type) {
-  base::AutoLock auto_lock(lock_);
-  io_thread_message_types_.insert(nested_msg_type);
-}
-
 scoped_refptr<base::MessageLoopProxy>
 ResourceReplyThreadRegistrar::GetTargetThread(
     const ResourceMessageReplyParams& reply_params,
     const IPC::Message& nested_msg) {
   base::AutoLock auto_lock(lock_);
   ResourceMap::iterator resource_iter = map_.find(reply_params.pp_resource());
   if (resource_iter != map_.end()) {
     SequenceThreadMap::iterator sequence_thread_iter =
         resource_iter->second.find(reply_params.sequence());
     if (sequence_thread_iter != resource_iter->second.end()) {
       scoped_refptr<base::MessageLoopProxy> target =
           sequence_thread_iter->second;
       resource_iter->second.erase(sequence_thread_iter);
       return target;
     }
   }
 
-  if (io_thread_message_types_.count(nested_msg.type()) != 0)
-    return scoped_refptr<base::MessageLoopProxy>();
-
   return main_thread_;
 }
 
 }  // namespace proxy
 }  // namespace ppapi