Cleanup: Remove unused variables in chrome/ found by Scythe.

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 ScriptContext;
 
 // 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:
   ~ChromeV8ExtensionHandler() override;
 
   // IPC::Listener
   bool OnMessageReceived(const IPC::Message& message) override = 0;
 
  protected:
-  explicit ChromeV8ExtensionHandler(ScriptContext* context);
+  ChromeV8ExtensionHandler();
   int GetRoutingID();
   void Send(IPC::Message* message);
-  ScriptContext* context_;
 
  private:
   int routing_id_;
   DISALLOW_COPY_AND_ASSIGN(ChromeV8ExtensionHandler);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_RENDERER_EXTENSIONS_CHROME_V8_EXTENSION_HANDLER_H_