Cleanup of v8 extension stuff. Playback extension is only used in chrome, so move it to chrome\rend…

webkit/extensions/v8/playback_extension.h

-// Copyright (c) 2011 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 WEBKIT_EXTENSIONS_V8_PLAYBACK_EXTENSION_H_
-#define WEBKIT_EXTENSIONS_V8_PLAYBACK_EXTENSION_H_
-#pragma once
-
-#include "webkit/extensions/webkit_extensions_export.h"
-
-namespace v8 {
-class Extension;
-}
-
-namespace extensions_v8 {
-
-// Inject code which overrides a few common JS functions for implementing
-// randomness.  In order to implement effective record & playback of
-// websites, it is important that the URLs not change.  Many popular web
-// based apps use randomness in URLs to unique-ify urls for proxies.
-// Unfortunately, this breaks playback.
-// To work around this, we take the two most common client-side randomness
-// generators and make them constant.  They really need to be constant
-// (rather than a constant seed followed by constant change)
-// because the playback mode wants flexibility in how it plays them back
-// and cannot always guarantee that requests for randomness are played back
-// in exactly the same order in which they were recorded.
-class PlaybackExtension {
- public:
-  WEBKIT_EXTENSIONS_EXPORT static v8::Extension* Get();
-};
-
-}  // namespace extensions_v8
-
-#endif  // WEBKIT_EXTENSIONS_V8_PLAYBACK_EXTENSION_H_