Decouple IPC::MessageFilter from IPC::Channel

ipc/ipc_sync_message_filter.h

Index: ipc/ipc_sync_message_filter.h
diff --git a/ipc/ipc_sync_message_filter.h b/ipc/ipc_sync_message_filter.h
index 4e08a1afd5a2b1c1efac380c599c481774533bc1..70a113c03249131f84cb841393c4f5ebefa3119f 100644
--- a/ipc/ipc_sync_message_filter.h
+++ b/ipc/ipc_sync_message_filter.h
@@ -34,9 +34,9 @@ class IPC_EXPORT SyncMessageFilter : public MessageFilter, public Sender {
   virtual bool Send(Message* message) OVERRIDE;
 
   // MessageFilter implementation.
-  virtual void OnFilterAdded(Channel* channel) OVERRIDE;
-  virtual void OnChannelError() OVERRIDE;
-  virtual void OnChannelClosing() OVERRIDE;
+  virtual void OnFilterAdded(Sender* sender) OVERRIDE;
+  virtual void OnSenderError() OVERRIDE;
+  virtual void OnSenderClosing() OVERRIDE;
   virtual bool OnMessageReceived(const Message& message) OVERRIDE;
 
  protected:
@@ -48,7 +48,7 @@ class IPC_EXPORT SyncMessageFilter : public MessageFilter, public Sender {
   void SignalAllEvents();
 
   // The channel to which this filter was added.
-  Channel* channel_;
+  Sender* sender_;
 
   // The process's main thread.
   scoped_refptr<base::MessageLoopProxy> listener_loop_;