[Storage] Added tracing for blob creation

storage/browser/blob/blob_url_request_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 STORAGE_BROWSER_BLOB_BLOB_URL_REQUEST_JOB_H_
 #define STORAGE_BROWSER_BLOB_BLOB_URL_REQUEST_JOB_H_
 
 #include <map>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 55 matching lines @@
   void Seek(int64 offset);
 
   // For reading the blob.
   bool ReadLoop(int* bytes_read);
   bool ReadItem();
   void AdvanceItem();
   void AdvanceBytesRead(int result);
   bool ReadBytesItem(const BlobDataItem& item, int bytes_to_read);
   bool ReadFileItem(FileStreamReader* reader, int bytes_to_read);
 
-  void DidReadFile(int result);
+  void DidReadFile(int chunk_number, int result);
   void DeleteCurrentFileReader();
 
   int ComputeBytesToRead() const;
   int BytesReadCompleted();
 
   // These methods convert the result of blob data reading into response headers
   // and pass it to URLRequestJob's NotifyDone() or NotifyHeadersComplete().
   void NotifySuccess();
   void NotifyFailure(int);
   void HeadersCompleted(net::HttpStatusCode status_code);
@@ skipping 20 matching lines @@
 
   // Holds the buffer for read data with the IOBuffer interface.
   scoped_refptr<net::DrainableIOBuffer> read_buf_;
 
   // Is set when NotifyFailure() is called and reset when DidStart is called.
   bool error_;
 
   bool byte_range_set_;
   net::HttpByteRange byte_range_;
 
+  // Used to create unique id's for tracing.
+  int current_file_chunk_number_;
+
   scoped_ptr<net::HttpResponseInfo> response_info_;
 
   base::WeakPtrFactory<BlobURLRequestJob> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BlobURLRequestJob);
 };
 
 }  // namespace storage
 
 #endif  // STORAGE_BROWSER_BLOB_BLOB_URL_REQUEST_JOB_H_