Use FilterContext to allow filters to access URLRequestJob data...

net/url_request/url_request_file_job.h

 // Copyright (c) 2006-2008 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 NET_URL_REQUEST_URL_REQUEST_FILE_JOB_H_
 #define NET_URL_REQUEST_URL_REQUEST_FILE_JOB_H_
 
+#include <string>
+
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "net/base/completion_callback.h"
 #include "net/base/file_stream.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_job.h"
 
 // A request job that handles reading file URLs
 class URLRequestFileJob : public URLRequestJob {
  public:
   URLRequestFileJob(URLRequest* request, const FilePath& file_path);
   virtual ~URLRequestFileJob();
 
   virtual void Start();
   virtual void Kill();
   virtual bool ReadRawData(net::IOBuffer* buf, int buf_size, int* bytes_read);
   virtual bool IsRedirectResponse(GURL* location, int* http_status_code);
-  virtual bool GetMimeType(std::string* mime_type);
+  virtual bool GetMimeType(std::string* mime_type) const;
 
   static URLRequest::ProtocolFactory Factory;
 
  protected:
   // The OS-specific full path name of the file
   FilePath file_path_;
 
  private:
   void DidResolve(bool exists, const file_util::FileInfo& file_info);
   void DidRead(int result);
 
   net::CompletionCallbackImpl<URLRequestFileJob> io_callback_;
   net::FileStream stream_;
   bool is_directory_;
 
 #if defined(OS_WIN)
   class AsyncResolver;
   friend class AsyncResolver;
   scoped_refptr<AsyncResolver> async_resolver_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(URLRequestFileJob);
 };
 
 #endif  // NET_URL_REQUEST_URL_REQUEST_FILE_JOB_H_