[mojo] Implement pipe fusion API

mojo/public/cpp/system/message_pipe.h

Index: mojo/public/cpp/system/message_pipe.h
diff --git a/mojo/public/cpp/system/message_pipe.h b/mojo/public/cpp/system/message_pipe.h
index 94818e88d950416d69ec06c9b6014d9a5e3bdc44..a56021d75d7e5ae223239ee9e133cc9a88878d1c 100644
--- a/mojo/public/cpp/system/message_pipe.h
+++ b/mojo/public/cpp/system/message_pipe.h
@@ -88,6 +88,14 @@ inline MojoResult ReadMessageRaw(MessagePipeHandle message_pipe,
       message_pipe.value(), bytes, num_bytes, handles, num_handles, flags);
 }
 
+// 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.
 class MessagePipe {