extensions: Cleanup class/struct fwd declarations

extensions/browser/api/web_request/web_request_api.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 EXTENSIONS_BROWSER_API_WEB_REQUEST_WEB_REQUEST_API_H_
 #define EXTENSIONS_BROWSER_API_WEB_REQUEST_WEB_REQUEST_API_H_
 
 #include <stdint.h>
 
 #include <list>
@@ skipping 21 matching lines @@
 #include "ipc/ipc_sender.h"
 #include "net/base/completion_callback.h"
 #include "net/base/network_delegate.h"
 #include "net/http/http_request_headers.h"
 
 class ExtensionWebRequestTimeTracker;
 class GURL;
 
 namespace base {
 class DictionaryValue;
-class ListValue;
-class StringValue;
 }
 
 namespace content {
 class BrowserContext;
 }
 
 namespace net {
 class AuthChallengeInfo;
 class AuthCredentials;
 class HttpRequestHeaders;
@@ skipping 573 matching lines @@
       extensions::QuotaLimitHeuristics* heuristics) const override;
   // Handle quota exceeded gracefully: Only warn the user but still execute the
   // function.
   void OnQuotaExceeded(const std::string& error) override;
   ResponseAction Run() override;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_WEB_REQUEST_WEB_REQUEST_API_H_