[Downloads] Use the initiating StoragePartition for resumption.

components/history/core/browser/download_database.h

Index: components/history/core/browser/download_database.h
diff --git a/components/history/core/browser/download_database.h b/components/history/core/browser/download_database.h
index 04cdfed54b9a0daf5a560a4bcc9b2339cf059854..6388195eccf2b1b0f314fe86c21487ce10a6fd21 100644
--- a/components/history/core/browser/download_database.h
+++ b/components/history/core/browser/download_database.h
@@ -87,6 +87,10 @@ class DownloadDatabase {
   // download table.
   bool MigrateDownloadTabUrl();
 
+  // Returns true if able to add the site_url column to the download
+  // table.
+  bool MigrateDownloadSiteInstanceUrl();
+
   // Creates the downloads table if needed.
   bool InitDownloadTable();