Mojo: Add static factory functions to MessagePipe.

mojo/system/message_pipe.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_PIPE_H_
 #define MOJO_SYSTEM_MESSAGE_PIPE_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 19 matching lines @@
 
 // |MessagePipe| is the secondary object implementing a message pipe (see the
 // explanatory comment in core.cc). It is typically owned by the dispatcher(s)
 // corresponding to the local endpoints. This class is thread-safe.
 class MOJO_SYSTEM_IMPL_EXPORT MessagePipe
     : public base::RefCountedThreadSafe<MessagePipe> {
  public:
   MessagePipe(scoped_ptr<MessagePipeEndpoint> endpoint0,
               scoped_ptr<MessagePipeEndpoint> endpoint1);
 
-  // Convenience constructor that constructs a |MessagePipe| with two new
-  // |LocalMessagePipeEndpoint|s.
-  MessagePipe();
+  // Constructs a |MessagePipe| with two new |LocalMessagePipeEndpoint|s.
+  struct LocalLocal {};
+  explicit MessagePipe(LocalLocal);
+
+  // Constructs a |MessagePipe| with a |LocalMessagePipeEndpoint| on port 0 and
+  // a |ProxyMessagePipeEndpoint| on port 1.
+  struct LocalProxy {};
+  explicit MessagePipe(LocalProxy);
+
+  // Constructs a |MessagePipe| with a |ProxyMessagePipeEndpoint| on port 0 and
+  // a |LocalMessagePipeEndpoint| on port 1.
+  // Note: This is really only needed in tests (outside of tests, this
+  // configuration arises from a local message pipe having its port 0
+  // "converted" using |ConvertLocalToProxy()|).
+  struct ProxyLocal {};
+  explicit MessagePipe(ProxyLocal);
 
   // Gets the other port number (i.e., 0 -> 1, 1 -> 0).
   static unsigned GetPeerPort(unsigned port);
 
   // Gets the type of the endpoint (used for assertions, etc.).
   MessagePipeEndpoint::Type GetType(unsigned port);
 
   // These are called by the dispatcher to implement its methods of
   // corresponding names. In all cases, the port |port| must be open.
   void CancelAllWaiters(unsigned port);
@@ skipping 64 matching lines @@
   base::Lock lock_;  // Protects the following members.
   scoped_ptr<MessagePipeEndpoint> endpoints_[2];
 
   DISALLOW_COPY_AND_ASSIGN(MessagePipe);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_MESSAGE_PIPE_H_