sync: Remove dead code related to ClearUserData

sync/internal_api/js_sync_manager_observer.cc

Index: sync/internal_api/js_sync_manager_observer.cc
diff --git a/sync/internal_api/js_sync_manager_observer.cc b/sync/internal_api/js_sync_manager_observer.cc
index 9f8848d8499ef044b75e88fa1a1b07c605178312..e74db84e2df484a272708ebc828a3060559c02dc 100644
--- a/sync/internal_api/js_sync_manager_observer.cc
+++ b/sync/internal_api/js_sync_manager_observer.cc
@@ -78,13 +78,6 @@ void JsSyncManagerObserver::OnInitializationComplete(
                 JsEventDetails(&details));
 }
 
-void JsSyncManagerObserver::OnStopSyncingPermanently() {
-  if (!event_handler_.IsInitialized()) {
-    return;
-  }
-  HandleJsEvent(FROM_HERE, "onStopSyncingPermanently", JsEventDetails());
-}
-
 void JsSyncManagerObserver::HandleJsEvent(
     const tracked_objects::Location& from_here,
     const std::string& name, const JsEventDetails& details) {