PVer4: Add UMA metrics for time taken to: load DB, do prefix check,

components/safe_browsing_db/v4_database.h

Index: components/safe_browsing_db/v4_database.h
diff --git a/components/safe_browsing_db/v4_database.h b/components/safe_browsing_db/v4_database.h
index 9c2e40541efb72fb0f25c5265c4eb43562717200..5601e72bdd28c5ddb57aa20d0d666dfb7576ea96 100644
--- a/components/safe_browsing_db/v4_database.h
+++ b/components/safe_browsing_db/v4_database.h
@@ -164,7 +164,8 @@ class V4Database {
       const base::FilePath& base_path,
       const ListInfos& list_infos,
       const scoped_refptr<base::SingleThreadTaskRunner>& callback_task_runner,
-      NewDatabaseReadyCallback callback);
+      NewDatabaseReadyCallback callback,
+      const base::TimeTicks create_start_time);
 
   // Callback called when a new store has been created and is ready to be used.
   // This method updates the store_map_ to point to the new store, which causes