Mojo: Add Channel::AttachEndpoint(), which takes a ChannelEndpoint.

mojo/system/channel_endpoint.h

 // Copyright 2014 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_CHANNEL_ENDPOINT_H_
 #define MOJO_SYSTEM_CHANNEL_ENDPOINT_H_
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 138 matching lines @@
     STATE_WAIT_REMOTE_REMOVE_ACK,
   };
 
   // TODO(vtl): This is totally temporary, until this becomes a proper
   // self-contained class. See the plan above.
   friend class Channel;
 
   friend class base::RefCountedThreadSafe<ChannelEndpoint>;
   ~ChannelEndpoint();
 
+  // Must be called with |lock_| held.
+  bool WriteMessageNoLock(scoped_ptr<MessageInTransit> message);
+
+  // TODO(vtl): Move these under lock.
   State state_;
   // TODO(vtl): When moved under lock, this can/should be made a raw pointer.
   scoped_refptr<MessagePipe> message_pipe_;
   unsigned port_;
 
   // TODO(vtl): Move the things above under lock.
   // Protects the members below.
   base::Lock lock_;
 
   // |channel_| must be alive whenever this is non-null. Before the |channel_|
   // gives up its reference to this object, it will call |DetachFromChannel()|.
   Channel* channel_;
   MessageInTransit::EndpointId local_id_;
   MessageInTransit::EndpointId remote_id_;
 
   DISALLOW_COPY_AND_ASSIGN(ChannelEndpoint);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_CHANNEL_ENDPOINT_H_