Let IPC::SyncMessageFilter take advantage of thread-safe Send.

ppapi/proxy/plugin_dispatcher.cc

 // Copyright (c) 2012 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/plugin_dispatcher.h"
 
 #include <map>
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
@@ skipping 153 matching lines @@
     PluginDelegate* delegate,
     base::ProcessId peer_pid,
     const IPC::ChannelHandle& channel_handle,
     bool is_client) {
   if (!Dispatcher::InitWithChannel(delegate, peer_pid, channel_handle,
                                    is_client))
     return false;
   plugin_delegate_ = delegate;
   plugin_dispatcher_id_ = plugin_delegate_->Register(this);
 
-  sync_filter_ = new IPC::SyncMessageFilter(delegate->GetShutdownEvent());
-  channel()->AddFilter(sync_filter_.get());
+  sync_filter_ = channel()->CreateSyncMessageFilter();
 
   // The message filter will intercept and process certain messages directly
   // on the I/O thread.
   channel()->AddFilter(
       new PluginMessageFilter(
           delegate->GetGloballySeenInstanceIDSet(),
           PluginGlobals::Get()->resource_reply_thread_registrar()));
   return true;
 }
 
@@ skipping 153 matching lines @@
   // once they're set. The user will have to restart to get new font prefs
   // propogated to plugins.
   if (!received_preferences_) {
     received_preferences_ = true;
     preferences_ = prefs;
   }
 }
 
 }  // namespace proxy
 }  // namespace ppapi