Properly handle the case when a parallel download becomes non-parallel

content/browser/download/parallel_download_utils.h

 // Copyright 2017 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_PARALLEL_DOWNLOAD_UTILS_H_
 #define CONTENT_BROWSER_DOWNLOAD_PARALLEL_DOWNLOAD_UTILS_H_
 
 #include <vector>
 
 #include "content/browser/download/download_create_info.h"
@@ skipping 39 matching lines @@
 // Get the time delay to send parallel requests after the response of original
 // request is handled.
 CONTENT_EXPORT base::TimeDelta GetParallelRequestDelayConfig();
 
 // Get the required remaining time before creating parallel requests.
 CONTENT_EXPORT base::TimeDelta GetParallelRequestRemainingTimeConfig();
 
 // Print the states of received slices for debugging.
 CONTENT_EXPORT void DebugSlicesInfo(const DownloadItem::ReceivedSlices& slices);
 
+// Given an ordered array of slices, get the maximum size of a contiguous data
+// block that starts from offset 0. If the first slice doesn't start from offset
+// 0, return 0.
+CONTENT_EXPORT int64_t GetMaxContiguousDataBlockSizeFromBeginning(
+    const DownloadItem::ReceivedSlices& slices);
 }  //  namespace content
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_PARALLEL_DOWNLOAD_UTILS_H_