Mojo: Use new message APIs to reduce copying

mojo/public/cpp/system/message_pipe.h

 // Copyright 2014 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.
 
 // This file provides a C++ wrapping around the Mojo C API for message pipes,
 // replacing the prefix of "Mojo" with a "mojo" namespace, and using more
 // strongly-typed representations of |MojoHandle|s.
 //
 // Please see "mojo/public/c/system/message_pipe.h" for complete documentation
 // of the API.
 
 #ifndef MOJO_PUBLIC_CPP_SYSTEM_MESSAGE_PIPE_H_
 #define MOJO_PUBLIC_CPP_SYSTEM_MESSAGE_PIPE_H_
 
 #include <stdint.h>
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "mojo/public/c/system/message_pipe.h"
 #include "mojo/public/cpp/system/handle.h"
+#include "mojo/public/cpp/system/message.h"
 
 namespace mojo {
 
 // A strongly-typed representation of a |MojoHandle| to one end of a message
 // pipe.
 class MessagePipeHandle : public Handle {
  public:
   MessagePipeHandle() {}
   explicit MessagePipeHandle(MojoHandle value) : Handle(value) {}
 
@@ skipping 50 matching lines @@
 inline MojoResult ReadMessageRaw(MessagePipeHandle message_pipe,
                                  void* bytes,
                                  uint32_t* num_bytes,
                                  MojoHandle* handles,
                                  uint32_t* num_handles,
                                  MojoReadMessageFlags flags) {
   return MojoReadMessage(
       message_pipe.value(), bytes, num_bytes, handles, num_handles, flags);
 }
 
+// Writes to a message pipe. Takes ownership of |message| and any attached
+// handles.
+inline MojoResult WriteMessageNew(MessagePipeHandle message_pipe,
+                                  ScopedMessageHandle message,
+                                  MojoWriteMessageFlags flags) {
+  return MojoWriteMessageNew(
+      message_pipe.value(), message.release().value(), flags);
+}
+
+// Reads from a message pipe. See |MojoReadMessageNew()| for complete
+// documentation.
+inline MojoResult ReadMessageNew(MessagePipeHandle message_pipe,
+                                 ScopedMessageHandle* message,
+                                 uint32_t* num_bytes,
+                                 MojoHandle* handles,
+                                 uint32_t* num_handles,
+                                 MojoReadMessageFlags flags) {
+  MojoMessageHandle raw_message;
+  MojoResult rv = MojoReadMessageNew(message_pipe.value(), &raw_message,
+                                     num_bytes, handles, num_handles, flags);
+  if (rv != MOJO_RESULT_OK)
+    return rv;
+
+  message->reset(MessageHandle(raw_message));
+  return MOJO_RESULT_OK;
+}
+
 // Fuses two message pipes together at the given handles. See
 // |MojoFuseMessagePipes()| for complete documentation.
 inline MojoResult FuseMessagePipes(ScopedMessagePipeHandle message_pipe0,
                                    ScopedMessagePipeHandle message_pipe1) {
   return MojoFuseMessagePipes(message_pipe0.release().value(),
                               message_pipe1.release().value());
 }
 
 // A wrapper class that automatically creates a message pipe and owns both
 // handles.
@@ skipping 16 matching lines @@
   MojoResult result = CreateMessagePipe(&options, &handle0, &handle1);
   DCHECK_EQ(MOJO_RESULT_OK, result);
 }
 
 inline MessagePipe::~MessagePipe() {
 }
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_SYSTEM_MESSAGE_PIPE_H_