Add experiment to measure time to hash extension content as we read it

net/url_request/url_request_file_job.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 NET_URL_REQUEST_URL_REQUEST_FILE_JOB_H_
 #define NET_URL_REQUEST_URL_REQUEST_FILE_JOB_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 30 matching lines @@
   virtual bool ReadRawData(IOBuffer* buf,
                            int buf_size,
                            int* bytes_read) OVERRIDE;
   virtual bool IsRedirectResponse(GURL* location,
                                   int* http_status_code) OVERRIDE;
   virtual Filter* SetupFilter() const OVERRIDE;
   virtual bool GetMimeType(std::string* mime_type) const OVERRIDE;
   virtual void SetExtraRequestHeaders(
       const HttpRequestHeaders& headers) OVERRIDE;
 
+  // An interface for subclasses who wish to monitor read operations.
+  virtual void OnSeekComplete(int64 result);
+  virtual void OnReadComplete(net::IOBuffer* buf, int result);
+
  protected:
   virtual ~URLRequestFileJob();
 
   // The OS-specific full path name of the file
   base::FilePath file_path_;
 
  private:
   // Meta information about the file. It's used as a member in the
   // URLRequestFileJob and also passed between threads because disk access is
   // necessary to obtain it.
@@ skipping 20 matching lines @@
   // Callback after fetching file info on a background thread.
   void DidFetchMetaInfo(const FileMetaInfo* meta_info);
 
   // Callback after opening file on a background thread.
   void DidOpen(int result);
 
   // Callback after seeking to the beginning of |byte_range_| in the file
   // on a background thread.
   void DidSeek(int64 result);
 
-  // Callback after data is asynchronously read from the file.
-  void DidRead(int result);
+  // Callback after data is asynchronously read from the file into |buf|.
+  void DidRead(net::IOBuffer* buf, int result);
 
   scoped_ptr<FileStream> stream_;
   FileMetaInfo meta_info_;
   const scoped_refptr<base::TaskRunner> file_task_runner_;
 
   HttpByteRange byte_range_;
   int64 remaining_bytes_;
 
   base::WeakPtrFactory<URLRequestFileJob> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(URLRequestFileJob);
 };
 
 }  // namespace net
 
 #endif  // NET_URL_REQUEST_URL_REQUEST_FILE_JOB_H_