[DevTools] Move DevToolsClientHost functionality out of DevToolsFrontendHost.

content/public/browser/devtools_frontend_host_delegate.h

-// Copyright (c) 2012 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 CONTENT_PUBLIC_BROWSER_DEVTOOLS_FRONTEND_HOST_DELEGATE_H_
-#define CONTENT_PUBLIC_BROWSER_DEVTOOLS_FRONTEND_HOST_DELEGATE_H_
-
-#include <string>
-
-namespace content {
-
-// Clients that want to use default DevTools front-end implementation should
-// implement this interface to provide access to the embedding browser from
-// the front-end.
-class DevToolsFrontendHostDelegate {
- public:
-  virtual ~DevToolsFrontendHostDelegate() {}
-
-  // Dispatch the message from the frontend to the frontend host.
-  virtual void DispatchOnEmbedder(const std::string& message) = 0;
-
-  // This method is called when the contents inspected by this devtools frontend
-  // is closing.
-  virtual void InspectedContentsClosing() = 0;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_PUBLIC_BROWSER_DEVTOOLS_FRONTEND_HOST_DELEGATE_H_