Fix an issue that we didn't clean url request properly.

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 b4a1d46dfd2b3f407c0fab0a68a94bf8d7f7bcd5..e46aca2272e6115fa09e8341e83d95172d80d205 100644
--- a/content/browser/download/download_item_impl.cc
+++ b/content/browser/download/download_item_impl.cc
@@ -1061,6 +1061,12 @@ void DownloadItemImpl::UpdateValidatorsOnResumption(
   // notified when the download transitions to the IN_PROGRESS state.
 }
 
+void DownloadItemImpl::CancelRequestWithOffset(int64_t offset) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (job_)
+    job_->CancelRequestWithOffset(offset);

[asanka, 2017/04/21 15:09:28]

It is possible that this will cancel the only request, correct? In which case
the download should be canceled?

I ask because I don't see any tests that exercise that possibility. The control
paths that are affected are quite convoluted and currently in flux. There should
be tests for these cases or there's a pretty good chance that things will break.

[xingliu, 2017/04/22 00:07:24]

If this call cancelled the only request, the download file should inform the
download item interruption or completion right after that.

It's not expected to cancel the download with this function in any case, but to
clean up a particular request, since the way we null out the ByteStreamReader in
DownloadFileImpl does not actually close the url request.

+}
+
 void DownloadItemImpl::NotifyRemoved() {
   for (auto& observer : observers_)
     observer.OnDownloadRemoved(this);
@@ -1313,6 +1319,8 @@ void DownloadItemImpl::StartDownload() {
                  base::Unretained(download_file_.get()),
                  base::Bind(&DownloadItemImpl::OnDownloadFileInitialized,
                             weak_ptr_factory_.GetWeakPtr()),
+                 base::Bind(&DownloadItemImpl::CancelRequestWithOffset,
+                            weak_ptr_factory_.GetWeakPtr()),
                  received_slices_));
 }