Move c/r/extensions/* into extensions namespace

chrome/renderer/extensions/chrome_v8_extension_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_RENDERER_EXTENSIONS_CHROME_V8_EXTENSION_HANDLER_H_
 #define CHROME_RENDERER_EXTENSIONS_CHROME_V8_EXTENSION_HANDLER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "ipc/ipc_listener.h"
 #include "v8/include/v8.h"
 
+namespace extensions {
 class ChromeV8Context;
 
 // Base class for context-scoped handlers used with ChromeV8Extension.
 // TODO(koz): Rename/refactor this somehow. Maybe just pull it into
 // ChromeV8Extension.
 class ChromeV8ExtensionHandler : public IPC::Listener {
  public:
   virtual ~ChromeV8ExtensionHandler();
 
   // IPC::Listener
   virtual bool OnMessageReceived(const IPC::Message& message) = 0;
 
  protected:
   explicit ChromeV8ExtensionHandler(ChromeV8Context* context);
   int GetRoutingID();
   void Send(IPC::Message* message);
   ChromeV8Context* context_;
 
  private:
   int routing_id_;
   DISALLOW_COPY_AND_ASSIGN(ChromeV8ExtensionHandler);
 };
 
+}  // namespace extensions
+
 #endif  // CHROME_RENDERER_EXTENSIONS_CHROME_V8_EXTENSION_HANDLER_H_