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

content/browser/download/download_item_impl.cc

Index: content/browser/download/download_item_impl.cc
diff --git a/content/browser/download/download_item_impl.cc b/content/browser/download/download_item_impl.cc
index 2d0a2c4a7489b3298a2e9eb0e73697350c036d9d..b4a1d46dfd2b3f407c0fab0a68a94bf8d7f7bcd5 100644
--- a/content/browser/download/download_item_impl.cc
+++ b/content/browser/download/download_item_impl.cc
@@ -1292,6 +1292,14 @@ void DownloadItemImpl::Start(
   if (state_ == RESUMING_INTERNAL)
     UpdateValidatorsOnResumption(new_create_info);
 
+  // If the download uses parallel requests, and choose not to create parallel
+  // request during resumption, clear the received_slices_ vector.
+  if (!job_->UsesParallelRequests() && !received_slices_.empty()) {
+    received_bytes_ =
+        GetMaxContiguousDataBlockSizeFromBeginning(received_slices_);
+    received_slices_.clear();
+  }
+
   TransitionTo(TARGET_PENDING_INTERNAL);
 
   job_->Start();