Allow proxy channels to be created without initializing the underlying channel.

ipc/ipc_channel_proxy.h

 // Copyright (c) 2011 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_CHANNEL_PROXY_H_
 #define IPC_IPC_CHANNEL_PROXY_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 102 matching lines @@
   // method is called on the thread where the IPC::Channel is running.  The
   // filter may be null if the consumer is not interested in handling messages
   // on the background thread.  Any message not handled by the filter will be
   // dispatched to the listener.  The given message loop indicates where the
   // IPC::Channel should be created.
   ChannelProxy(const IPC::ChannelHandle& channel_handle,
                Channel::Mode mode,
                Channel::Listener* listener,
                base::MessageLoopProxy* ipc_thread_loop);
 
+  // Creates an uninitialized channel proxy. Init must be called to receive
+  // or send any messages. This two-step setup allows message filters to be
+  // added before any messages are sent or received.
+  ChannelProxy(Channel::Listener* listener,
+               base::MessageLoopProxy* ipc_thread_loop);
+
   virtual ~ChannelProxy();
 
+  // Initializes the channel proxy. Only call this once to initialize a channel
+  // proxy that was not initialized in its constructor. If create_pipe_now is
+  // true, the pipe is created synchronously. Otherwise it's created on the IO
+  // thread.
+  void Init(const IPC::ChannelHandle& channel_handle, Channel::Mode mode,
+            bool create_pipe_now);
+
   // Close the IPC::Channel.  This operation completes asynchronously, once the
   // background thread processes the command to close the channel.  It is ok to
   // call this method multiple times.  Redundant calls are ignored.
   //
   // WARNING: The MessageFilter object held by the ChannelProxy is also
   // released asynchronously, and it may in fact have its final reference
   // released on the background thread.  The caller should be careful to deal
   // with / allow for this possibility.
   void Close();
 
@@ skipping 23 matching lines @@
 #if defined(OS_POSIX)
   // Calls through to the underlying channel's methods.
   int GetClientFileDescriptor();
   int TakeClientFileDescriptor();
   bool GetClientEuid(uid_t* client_euid) const;
 #endif  // defined(OS_POSIX)
 
  protected:
   class Context;
   // A subclass uses this constructor if it needs to add more information
-  // to the internal state.  If create_pipe_now is true, the pipe is created
-  // immediately.  Otherwise it's created on the IO thread.
-  ChannelProxy(const IPC::ChannelHandle& channel_handle,
-               Channel::Mode mode,
-               base::MessageLoopProxy* ipc_thread_loop,
-               Context* context,
-               bool create_pipe_now);
+  // to the internal state.
+  ChannelProxy(Context* context);
 
   // Used internally to hold state that is referenced on the IPC thread.
   class Context : public base::RefCountedThreadSafe<Context>,
                   public Channel::Listener {
    public:
     Context(Channel::Listener* listener, base::MessageLoopProxy* ipc_thread);
     void ClearIPCMessageLoop() { ipc_message_loop_ = NULL; }
     base::MessageLoopProxy* ipc_message_loop() const {
       return ipc_message_loop_.get();
     }
@@ skipping 65 matching lines @@
 
   Context* context() { return context_; }
 
   OutgoingMessageFilter* outgoing_message_filter() {
     return outgoing_message_filter_;
   }
 
  private:
   friend class SendTask;
 
-  void Init(const IPC::ChannelHandle& channel_handle, Channel::Mode mode,
-            base::MessageLoopProxy* ipc_thread_loop, bool create_pipe_now);
-
   // By maintaining this indirection (ref-counted) to our internal state, we
   // can safely be destroyed while the background thread continues to do stuff
   // that involves this data.
   scoped_refptr<Context> context_;
 
   OutgoingMessageFilter* outgoing_message_filter_;
+
+  // Whether the channel has been initialized.
+  bool did_init_;
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_PROXY_H_