Fixed a crash in AutoResumptionHandler

This crash could possibly happen since we are clearing out the downloads
in OnDownloadRemoved rather than OnDownloadDestroyed. The destroyed is
a super set and is safer to use.

Bug:991621

Change-Id: Id90e8b259b36a3886ff16cd321363e25c81a6c06
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1742530Reviewed-by: Shakti Sahu <shaktisahu@chromium.org>
Reviewed-by: Min Qin <qinmin@chromium.org>
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685232}

components/download/public/common/auto_resumption_handler.cc

@@ -169,6 +169,7 @@ void AutoResumptionHandler::OnDownloadRemoved(download::DownloadItem* item) {
 }
 
 void AutoResumptionHandler::OnDownloadDestroyed(download::DownloadItem* item) {
+  resumable_downloads_.erase(item->GetGuid());
   downloads_to_retry_.erase(item);
 }