Mojo: Move the paused message queue from ProxyMessagePipeEndpoint to ChannelEndpoint.

mojo/system/proxy_message_pipe_endpoint.h

 // 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.
 
 #ifndef MOJO_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_
 #define MOJO_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "mojo/system/message_in_transit.h"
-#include "mojo/system/message_in_transit_queue.h"
 #include "mojo/system/message_pipe_endpoint.h"
 #include "mojo/system/system_impl_export.h"
 
 namespace mojo {
 namespace system {
 
 class ChannelEndpoint;
 class LocalMessagePipeEndpoint;
 class MessagePipe;
 
 // A |ProxyMessagePipeEndpoint| connects an end of a |MessagePipe| to a
 // |Channel|, over which it transmits and receives data (to/from another
 // |ProxyMessagePipeEndpoint|). So a |MessagePipe| with one endpoint local and
 // the other endpoint remote consists of a |LocalMessagePipeEndpoint| and a
 // |ProxyMessagePipeEndpoint|, with only the local endpoint being accessible via
 // a |MessagePipeDispatcher|.
 //
 // Like any |MessagePipeEndpoint|, a |ProxyMessagePipeEndpoint| is owned by a
 // |MessagePipe|.
 //  - A |ProxyMessagePipeEndpoint| starts out *detached*, i.e., not associated
 //    to any |Channel|. When *attached*, it gets a reference to a |Channel| and
 //    is assigned a local ID. A |ProxyMessagePipeEndpoint| must be detached
 //    before destruction; this is done inside |Close()|.
 //  - When attached, a |ProxyMessagePipeEndpoint| starts out not running. When
 //    run, it gets a remote ID.
 class MOJO_SYSTEM_IMPL_EXPORT ProxyMessagePipeEndpoint
     : public MessagePipeEndpoint {
  public:
   explicit ProxyMessagePipeEndpoint(ChannelEndpoint* channel_endpoint);
-  // Constructs a |ProxyMessagePipeEndpoint| that replaces the given
-  // |LocalMessagePipeEndpoint| (which this constructor will close), taking its
-  // message queue's contents. This is done when transferring a message pipe
-  // handle over a remote message pipe.
+  // Constructs a |ProxyMessagePipeEndpoint|, whose peer may already be closed.
+  // This is used to construct one to replace a |LocalMessagePipeEndpoint|, when
+  // transferring a message pipe handle over a remote message pipe.
   ProxyMessagePipeEndpoint(
       ChannelEndpoint* channel_endpoint,
-      LocalMessagePipeEndpoint* local_message_pipe_endpoint,
       bool is_peer_open);
   virtual ~ProxyMessagePipeEndpoint();
 
   // |MessagePipeEndpoint| implementation:
   virtual Type GetType() const OVERRIDE;
   virtual bool OnPeerClose() OVERRIDE;
   virtual void EnqueueMessage(scoped_ptr<MessageInTransit> message) OVERRIDE;
   virtual bool Run() OVERRIDE;
   virtual void OnRemove() OVERRIDE;
 
  private:
   void Detach();
 
   // TODO(vtl): Get rid of these.
   bool is_attached() const { return !!channel_endpoint_.get(); }
   bool is_running() const { return is_running_; }
 
   // This should only be set if we're attached.
   scoped_refptr<ChannelEndpoint> channel_endpoint_;
 
   // TODO(vtl): Get rid of this.
   bool is_running_;
 
   bool is_peer_open_;
 
-  // This queue is only used while we're detached, to store messages while we're
-  // not ready to send them yet.
-  MessageInTransitQueue paused_message_queue_;
-
   DISALLOW_COPY_AND_ASSIGN(ProxyMessagePipeEndpoint);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_