Moves some files into mojo/common

mojo/shell/scoped_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_SHELL_SCOPED_MESSAGE_PIPE_H_
-#define MOJO_SHELL_SCOPED_MESSAGE_PIPE_H_
-
-#include "base/basictypes.h"
-#include "mojo/public/system/core.h"
-
-namespace mojo {
-namespace shell {
-
-// Simple scoper that creates a message pipe in constructor and closes it in
-// destructor. Test for success by comparing handles with MOJO_HANDLE_INVALID.
-class ScopedMessagePipe {
- public:
-  ScopedMessagePipe();
-  ~ScopedMessagePipe();
-
-  MojoHandle handle_0() const { return handle_0_; }
-  MojoHandle handle_1() const { return handle_1_; }
-
- private:
-  MojoHandle handle_0_;
-  MojoHandle handle_1_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedMessagePipe);
-};
-
-}  // namespace shell
-}  // namespace mojo
-
-#endif  // MOJO_SHELL_SCOPED_MESSAGE_PIPE_H_