[BlobStorage] Implementing disk.

storage/browser/fileapi/local_file_stream_reader.cc

 // 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.
 
 #include "storage/browser/fileapi/local_file_stream_reader.h"
 
 #include <stdint.h>
 
 #include "base/files/file_util.h"
 #include "base/files/file_util_proxy.h"
@@ skipping 142 matching lines @@
     const base::File::Info& file_info) {
   if (file_info.is_directory) {
     callback.Run(net::ERR_FILE_NOT_FOUND);
     return;
   }
   if (error != base::File::FILE_OK) {
     callback.Run(net::FileErrorToNetError(error));
     return;
   }
   if (!VerifySnapshotTime(expected_modification_time_, file_info)) {
+    LOG(ERROR) << "Expected time "
+               << expected_modification_time_.ToInternalValue()
+               << ", but actual time "
+               << file_info.last_modified.ToInternalValue();
+
     callback.Run(net::ERR_UPLOAD_FILE_CHANGED);
     return;
   }
   callback.Run(file_info.size);
 }
 
 }  // namespace storage