downloads: prevent "Clear all" from removing in progress downloads

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 753656fee29249a461a1830456242bbddf1e0d26..938f7cc2953c8d7e9995ad22b07a5a3fa0b726a0 100644
--- a/content/browser/download/download_item_impl.cc
+++ b/content/browser/download/download_item_impl.cc
@@ -414,7 +414,9 @@ void DownloadItemImpl::Cancel(bool user_cancel) {
   if (!is_save_package_download_ && download_file_)
     ReleaseDownloadFile(true);
 
-  if (state_ == IN_PROGRESS_INTERNAL) {
+  // |request_handle_| may be NULL during tests. TODO(dbeam): inject a fake one
+  // instead?
+  if (state_ == IN_PROGRESS_INTERNAL && request_handle_) {
     // Cancel the originating URL request unless it's already been cancelled
     // by interrupt.
     request_handle_->CancelRequest();