Mojo: Make some attempts towards fixing remote message pipe closure.

mojo/system/message_in_transit.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_MESSAGE_IN_TRANSIT_H_
 #define MOJO_SYSTEM_MESSAGE_IN_TRANSIT_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 36 matching lines @@
   static const Type kTypeMessagePipeEndpoint = 0;
   // Messages that are forwarded to |MessagePipe|s.
   static const Type kTypeMessagePipe = 1;
   // Messages that are consumed by the channel.
   static const Type kTypeChannel = 2;
 
   typedef uint16_t Subtype;
   // Subtypes for type |kTypeMessagePipeEndpoint|:
   static const Subtype kSubtypeMessagePipeEndpointData = 0;
   // Subtypes for type |kTypeMessagePipe|:
-  static const Subtype kSubtypeMessagePipePeerClosed = 0;
+  // Nothing currently.
   // Subtypes for type |kTypeChannel|:
   static const Subtype kSubtypeChannelRunMessagePipeEndpoint = 0;
+  static const Subtype kSubtypeChannelRemoveMessagePipeEndpoint = 1;
+  static const Subtype kSubtypeChannelRemoveMessagePipeEndpointAck = 2;
 
   typedef uint32_t EndpointId;
   // Never a valid endpoint ID.
   static const EndpointId kInvalidEndpointId = 0;
 
   // Messages (the header and data) must always be aligned to a multiple of this
   // quantity (which must be a power of 2).
   static const size_t kMessageAlignment = 8;
 
   // The maximum size of a single serialized dispatcher. This must be a multiple
@@ skipping 233 matching lines @@
   // TODO(vtl): With C++11, change it to a vector of |ScopedPlatformHandles|.
   scoped_ptr<std::vector<embedder::PlatformHandle> > platform_handles_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageInTransit);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_MESSAGE_IN_TRANSIT_H_