Move more Mojo bindings helpers out of internal namespace

mojo/public/cpp/bindings/lib/pipe_control_message_handler_delegate.h

-// Copyright 2015 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_PUBLIC_CPP_BINDINGS_LIB_PIPE_CONTROL_MESSAGE_HANDLER_DELEGATE_H_
-#define MOJO_PUBLIC_CPP_BINDINGS_LIB_PIPE_CONTROL_MESSAGE_HANDLER_DELEGATE_H_
-
-#include "mojo/public/cpp/bindings/interface_id.h"
-
-namespace mojo {
-namespace internal {
-
-class PipeControlMessageHandlerDelegate {
- public:
-  // The implementation of the following methods should return false if the
-  // notification is unexpected. In that case, the user of this delegate is
-  // expected to close the message pipe.
-  virtual bool OnPeerAssociatedEndpointClosed(InterfaceId id) = 0;
-  virtual bool OnAssociatedEndpointClosedBeforeSent(InterfaceId id) = 0;
-
- protected:
-  virtual ~PipeControlMessageHandlerDelegate() {}
-};
-
-}  // namespace internal
-}  // namespace mojo
-
-#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_PIPE_CONTROL_MESSAGE_HANDLER_DELEGATE_H_