Clean forward declaration in public

public/web/WebDataSource.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 19 matching lines @@
 
 #ifndef WebDataSource_h
 #define WebDataSource_h
 
 #include "../platform/WebCommon.h"
 #include "WebNavigationType.h"
 #include "WebTextDirection.h"
 
 namespace blink {
 
-class WebApplicationCacheHost;
-class WebString;
 class WebURL;
 class WebURLRequest;
 class WebURLResponse;
 template <typename T> class WebVector;
 
 class WebDataSource {
 public:
     class ExtraData {
     public:
         virtual ~ExtraData() { }
@@ skipping 58 matching lines @@
     // the user may have already recorded the original value.
     virtual void setNavigationStartTime(double) = 0;
 
 protected:
     ~WebDataSource() { }
 };
 
 } // namespace blink
 
 #endif