Mojo: Refactor some message pipe stuff.

mojo/system/local_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_LOCAL_MESSAGE_PIPE_ENDPOINT_H_
 #define MOJO_SYSTEM_LOCAL_MESSAGE_PIPE_ENDPOINT_H_
 
 #include <deque>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "mojo/public/system/core.h"
 #include "mojo/system/message_pipe_endpoint.h"
 #include "mojo/system/system_impl_export.h"
 #include "mojo/system/waiter_list.h"
 
 namespace mojo {
 namespace system {
 
 class MOJO_SYSTEM_IMPL_EXPORT LocalMessagePipeEndpoint
     : public MessagePipeEndpoint {
  public:
   LocalMessagePipeEndpoint();
   virtual ~LocalMessagePipeEndpoint();
 
   // |MessagePipeEndpoint| implementation:
   virtual void Close() OVERRIDE;
   virtual void OnPeerClose() OVERRIDE;
-  virtual MojoResult CanEnqueueMessage(
-      const MessageInTransit* message,
+  virtual MojoResult EnqueueMessage(
+      MessageInTransit* message,
       const std::vector<Dispatcher*>* dispatchers) OVERRIDE;
-  virtual void EnqueueMessage(
-      MessageInTransit* message,
-      std::vector<scoped_refptr<Dispatcher> >* dispatchers) OVERRIDE;
 
   // There's a dispatcher for |LocalMessagePipeEndpoint|s, so we have to
   // implement/override these:
   virtual void CancelAllWaiters() OVERRIDE;
   virtual MojoResult ReadMessage(
       void* bytes, uint32_t* num_bytes,
       std::vector<scoped_refptr<Dispatcher> >* dispatchers,
       uint32_t* num_dispatchers,
       MojoReadMessageFlags flags) OVERRIDE;
   virtual MojoResult AddWaiter(Waiter* waiter,
                                MojoWaitFlags flags,
                                MojoResult wake_result) OVERRIDE;
   virtual void RemoveWaiter(Waiter* waiter) OVERRIDE;
 
  private:
-  struct MessageQueueEntry {
+  class MessageQueueEntry {
+   public:
     MessageQueueEntry();
     // Provide an explicit copy constructor, so that we can use this directly in
     // a (C++03) STL container. However, we only allow the case where |other| is
     // empty. (We don't provide a nontrivial constructor, because it wouldn't be
     // useful with these constraints. This will change with C++11.)
     MessageQueueEntry(const MessageQueueEntry& other);
     ~MessageQueueEntry();
 
-    MessageInTransit* message;
-    std::vector<scoped_refptr<Dispatcher> > dispatchers;
+    // Initialize, taking ownership of |message| and creating equivalent
+    // "duplicate" |dispatchers|. |dispatchers| should be non-null only if
+    // nonempty.
+    // TODO(vtl): This would simply be a constructor, but we don't have C++11's
+    // emplace operations yet, and I don't want to copy |dispatchers_|.
+    void Init(MessageInTransit* message,
+              const std::vector<Dispatcher*>* dispatchers);
+
+    MessageInTransit* message() {
+      return message_;
+    }
+    std::vector<scoped_refptr<Dispatcher> >* dispatchers() {
+      return &dispatchers_;
+    }
 
    private:
+    MessageInTransit* message_;
+    std::vector<scoped_refptr<Dispatcher> > dispatchers_;
+
     // We don't need assignment, however.
     DISALLOW_ASSIGN(MessageQueueEntry);
   };
 
   MojoWaitFlags SatisfiedFlags();
   MojoWaitFlags SatisfiableFlags();
 
   bool is_open_;
   bool is_peer_open_;
 
   std::deque<MessageQueueEntry> message_queue_;
   WaiterList waiter_list_;
 
   DISALLOW_COPY_AND_ASSIGN(LocalMessagePipeEndpoint);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_LOCAL_MESSAGE_PIPE_ENDPOINT_H_