Make it possible to write a message pipe endpoint's peer into it.

mojo/edk/system/message_pipe_dispatcher.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_EDK_SYSTEM_MESSAGE_PIPE_DISPATCHER_H_
 #define MOJO_EDK_SYSTEM_MESSAGE_PIPE_DISPATCHER_H_
 
 #include "mojo/edk/system/dispatcher.h"
 #include "mojo/edk/system/memory.h"
 #include "mojo/edk/util/ref_ptr.h"
 #include "mojo/edk/util/thread_annotations.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
 namespace system {
 
 class ChannelEndpoint;
 class MessagePipe;
-class MessagePipeDispatcherTransport;
 
 // This is the |Dispatcher| implementation for message pipes (created by the
 // Mojo primitive |MojoCreateMessagePipe()|). This class is thread-safe.
 class MessagePipeDispatcher final : public Dispatcher {
  public:
   // The default options to use for |MojoCreateMessagePipe()|. (Real uses
   // should obtain this via |ValidateCreateOptions()| with a null |in_options|;
   // this is exposed directly for testing convenience.)
   static const MojoCreateMessagePipeOptions kDefaultCreateOptions;
 
@@ skipping 27 matching lines @@
   static util::RefPtr<MessagePipeDispatcher> CreateRemoteMessagePipe(
       util::RefPtr<ChannelEndpoint>* channel_endpoint);
 
   // The "opposite" of |SerializeAndClose()|. (Typically this is called by
   // |Dispatcher::Deserialize()|.)
   static util::RefPtr<MessagePipeDispatcher> Deserialize(Channel* channel,
                                                          const void* source,
                                                          size_t size);
 
  private:
-  friend class MessagePipeDispatcherTransport;
-
   MessagePipeDispatcher();
   ~MessagePipeDispatcher() override;
 
   // Gets a dumb pointer to |message_pipe_|. This must be called under the
   // |Dispatcher| lock (that it's a dumb pointer is okay since it's under lock).
   // This is needed when sending handles across processes, where nontrivial,
   // invasive work needs to be done.
   MessagePipe* GetMessagePipeNoLock() const;
   // Similarly for the port.
   unsigned GetPortNoLock() const;
 
   // |Dispatcher| protected methods:
   void CancelAllAwakablesNoLock() override;
   void CloseImplNoLock() override;
-  util::RefPtr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock()
-      override;
+  util::RefPtr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock(
+      MessagePipe* message_pipe,
+      unsigned port) override;
   MojoResult WriteMessageImplNoLock(
       UserPointer<const void> bytes,
       uint32_t num_bytes,
       std::vector<DispatcherTransport>* transports,
       MojoWriteMessageFlags flags) override;
   MojoResult ReadMessageImplNoLock(UserPointer<void> bytes,
                                    UserPointer<uint32_t> num_bytes,
                                    DispatcherVector* dispatchers,
                                    uint32_t* num_dispatchers,
                                    MojoReadMessageFlags flags) override;
@@ skipping 15 matching lines @@
       std::vector<platform::ScopedPlatformHandle>* platform_handles) override
       MOJO_NOT_THREAD_SAFE;
 
   // This will be null if closed.
   util::RefPtr<MessagePipe> message_pipe_ MOJO_GUARDED_BY(mutex());
   unsigned port_ MOJO_GUARDED_BY(mutex());
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MessagePipeDispatcher);
 };
 
-class MessagePipeDispatcherTransport : public DispatcherTransport {
- public:
-  explicit MessagePipeDispatcherTransport(DispatcherTransport transport);
-
-  MessagePipe* GetMessagePipe() {
-    return message_pipe_dispatcher()->GetMessagePipeNoLock();
-  }
-  unsigned GetPort() { return message_pipe_dispatcher()->GetPortNoLock(); }
-
- private:
-  MessagePipeDispatcher* message_pipe_dispatcher() {
-    return static_cast<MessagePipeDispatcher*>(dispatcher());
-  }
-
-  // Copy and assign allowed.
-};
-
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_MESSAGE_PIPE_DISPATCHER_H_