Moved ExtensionMessage* into extensions namespace

chrome/browser/extensions/extension_message_handler.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 CHROME_BROWSER_EXTENSIONS_EXTENSION_MESSAGE_HANDLER_H_
-#define CHROME_BROWSER_EXTENSIONS_EXTENSION_MESSAGE_HANDLER_H_
-
-#include <string>
-
-#include "content/public/browser/render_view_host_observer.h"
-
-// Filters and dispatches extension-related IPC messages that arrive from
-// renderers. There is one of these objects for each RenderViewHost in Chrome.
-// Contrast this with extensions::TabHelper, which is only created for
-// WebContents.
-//
-// TODO(aa): Handling of content script messaging should be able to move to EFD
-// once there is an EFD for every RVHD where extension code can run. Then we
-// could eliminate this class. Right now, we don't end up with an EFD for tab
-// contents unless that tab contents is hosting chrome-extension:// URLs. That
-// still leaves content scripts. See also: crbug.com/80307.
-class ExtensionMessageHandler : public content::RenderViewHostObserver {
- public:
-  // |sender| is guaranteed to outlive this object.
-  explicit ExtensionMessageHandler(content::RenderViewHost* render_view_host);
-  virtual ~ExtensionMessageHandler();
-
-  // RenderViewHostObserver overrides.
-  virtual void RenderViewHostInitialized() OVERRIDE;
-  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
-
- private:
-  // Message handlers.
-  void OnPostMessage(int port_id, const std::string& message);
-
-  DISALLOW_COPY_AND_ASSIGN(ExtensionMessageHandler);
-};
-
-#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_MESSAGE_HANDLER_H_