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

ipc/ipc_sync_channel.h

 // 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.
 
 #ifndef IPC_IPC_SYNC_CHANNEL_H_
 #define IPC_IPC_SYNC_CHANNEL_H_
 
 #include <string>
 #include <deque>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event_watcher.h"
 #include "ipc/ipc_channel_handle.h"
 #include "ipc/ipc_channel_proxy.h"
 #include "ipc/ipc_sync_message.h"
+#include "ipc/ipc_sync_message_filter.h"
 
 namespace base {
 class WaitableEvent;
 };
 
 namespace IPC {
 
 class SyncMessage;
 class ChannelFactory;
 
@@ skipping 81 matching lines @@
   // some cases where such loops are not possible. This flags allows the tagging
   // of some particular channels to only re-enter in known correct cases.
   //
   // Incoming messages on channels belonging to a group that is not
   // kRestrictDispatchGroup_None will only be dispatched while a sync message is
   // being sent on a channel of the *same* group.
   // Incoming messages belonging to the kRestrictDispatchGroup_None group (the
   // default) will be dispatched in any case.
   void SetRestrictDispatchChannelGroup(int group);
 
+  // Creates a new IPC::SyncMessageFilter and adds it to this SyncChannel.
+  // This should be used instead of directly constructing a new
+  // SyncMessageFilter.
+  scoped_refptr<IPC::SyncMessageFilter> CreateSyncMessageFilter();
+
  protected:
   class ReceivedSyncMsgQueue;
   friend class ReceivedSyncMsgQueue;
 
   // SyncContext holds the per object data for SyncChannel, so that SyncChannel
   // can be deleted while it's being used in a different thread.  See
   // ChannelProxy::Context for more information.
   class SyncContext : public Context {
    public:
     SyncContext(
@@ skipping 101 matching lines @@
   // Used to signal events between the IPC and listener threads.
   base::WaitableEventWatcher dispatch_watcher_;
   base::WaitableEventWatcher::EventCallback dispatch_watcher_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncChannel);
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_SYNC_CHANNEL_H_