Add the ability to check the CSD Whitelist asynchronously, for PhishGuard.

components/safe_browsing_db/remote_database_manager.cc

Index: components/safe_browsing_db/remote_database_manager.cc
diff --git a/components/safe_browsing_db/remote_database_manager.cc b/components/safe_browsing_db/remote_database_manager.cc
index b620426b711ce62c852adb3e22285256f731bf4b..6b78c53d191a276054ae3945a47af14324441468 100644
--- a/components/safe_browsing_db/remote_database_manager.cc
+++ b/components/safe_browsing_db/remote_database_manager.cc
@@ -258,6 +258,13 @@ bool RemoteSafeBrowsingDatabaseManager::CheckUrlForSubresourceFilter(
   return false;
 }
 
+AsyncMatch RemoteSafeBrowsingDatabaseManager::CheckCsdWhitelistUrl(
+    const GURL& url,
+    Client* client) {
+  NOTREACHED();
+  return AsyncMatch::MATCH;
+}
+
 bool RemoteSafeBrowsingDatabaseManager::MatchCsdWhitelistUrl(const GURL& url) {
   NOTREACHED();
   return true;