set content length limit if half open range request fails

content/browser/download/download_file.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 CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 57 matching lines @@
                                  const GURL& source_url,
                                  const GURL& referrer_url,
                                  const RenameCompletionCallback& callback) = 0;
 
   // Detach the file so it is not deleted on destruction.
   virtual void Detach() = 0;
 
   // Abort the download and automatically close the file.
   virtual void Cancel() = 0;
 
+  // Sets the potential file length. This is called when a half-open range
+  // request fails or completes successfully. If the range request fails, the
+  // file length should not be larger than the request's offset. If the range
+  // request completes successfully, the file length can be determined by
+  // the request offset and the bytes received. So |length| may not be the
+  // actual file length, but it should not be smaller than it.
+  virtual void SetPotentialFileLength(int64_t length) = 0;
+
   virtual const base::FilePath& FullPath() const = 0;
   virtual bool InProgress() const = 0;
   virtual void WasPaused() = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_H_