Revert of Straightens outs DEPS in mojo/common

mojo/message_pump/message_pump_mojo_handler.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_MESSAGE_PUMP_MESSAGE_PUMP_MOJO_HANDLER_H_
-#define MOJO_MESSAGE_PUMP_MESSAGE_PUMP_MOJO_HANDLER_H_
-
-#include "third_party/mojo/src/mojo/public/cpp/system/core.h"
-
-namespace mojo {
-namespace common {
-
-// Used by MessagePumpMojo to notify when a handle is either ready or has become
-// invalid. In case of error, the handler will be removed.
-class MessagePumpMojoHandler {
- public:
-  virtual void OnHandleReady(const Handle& handle) = 0;
-
-  virtual void OnHandleError(const Handle& handle, MojoResult result) = 0;
-
- protected:
-  virtual ~MessagePumpMojoHandler() {}
-};
-
-}  // namespace common
-}  // namespace mojo
-
-#endif  // MOJO_MESSAGE_PUMP_MESSAGE_PUMP_MOJO_HANDLER_H_