[Sync] Add type conversion constructor for WeakHandle

chrome/browser/sync/internal_api/sync_manager.cc

Index: chrome/browser/sync/internal_api/sync_manager.cc
diff --git a/chrome/browser/sync/internal_api/sync_manager.cc b/chrome/browser/sync/internal_api/sync_manager.cc
index 8359255a4899b0e8188ff6a4598b4ec29e13e90b..319f7779f6d7730bae391e166254ed0509e56aaf 100644
--- a/chrome/browser/sync/internal_api/sync_manager.cc
+++ b/chrome/browser/sync/internal_api/sync_manager.cc
@@ -826,7 +826,7 @@ bool SyncManager::SyncInternal::Init(
   // a freed pointer. This is because UI thread is not shut down.
   FOR_EACH_OBSERVER(SyncManager::Observer, observers_,
                     OnInitializationComplete(
-                        WeakHandle<JsBackend>(weak_ptr_factory_.GetWeakPtr()),
+                        MakeWeakHandle(weak_ptr_factory_.GetWeakPtr()),
                         signed_in));
 
   if (!signed_in && !setup_for_test_mode_)