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

mojo/system/channel_endpoint.h

Index: mojo/system/channel_endpoint.h
diff --git a/mojo/system/channel_endpoint.h b/mojo/system/channel_endpoint.h
index 7d85b8e35e80cf7c057170387182dc25660a8e34..78232a3d1512feed210c677d96da81cfd5fe1236 100644
--- a/mojo/system/channel_endpoint.h
+++ b/mojo/system/channel_endpoint.h
@@ -10,6 +10,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/lock.h"
 #include "mojo/system/message_in_transit.h"
+#include "mojo/system/message_in_transit_queue.h"
 #include "mojo/system/system_impl_export.h"
 
 namespace mojo {
@@ -112,6 +113,11 @@ class MOJO_SYSTEM_IMPL_EXPORT ChannelEndpoint
   // TODO(vtl): More comments....
   ChannelEndpoint(MessagePipe* message_pipe, unsigned port);
 
+  // Takes messages from the given |MessageInTransitQueue|. This must be called
+  // before this object is attached to a channel, and before anyone has a chance
+  // to enqueue any messages.
+  void TakeMessages(MessageInTransitQueue* message_queue);
+
   // Methods called by |MessagePipe| (via |ProxyMessagePipeEndpoint|):
 
   // TODO(vtl): This currently only works if we're "running". We'll move the
@@ -170,6 +176,10 @@ class MOJO_SYSTEM_IMPL_EXPORT ChannelEndpoint
   MessageInTransit::EndpointId local_id_;
   MessageInTransit::EndpointId remote_id_;
 
+  // This queue is used before we're running on a channel and ready to send
+  // messages.
+  MessageInTransitQueue paused_message_queue_;
+
   DISALLOW_COPY_AND_ASSIGN(ChannelEndpoint);
 };