Retry: sync: Gracefully handle early shutdown

sync/internal_api/public/base/cancelation_observer.cc

Index: sync/internal_api/public/base/cancelation_observer.cc
diff --git a/sync/internal_api/public/base/cancelation_observer.cc b/sync/internal_api/public/base/cancelation_observer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f50b6a3c077722e6d02703fcef056e1d5e5cbace
--- /dev/null
+++ b/sync/internal_api/public/base/cancelation_observer.cc
@@ -0,0 +1,13 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "sync/internal_api/public/base/cancelation_observer.h"
+
+namespace syncer {
+
+CancelationObserver::CancelationObserver() {}
+
+CancelationObserver::~CancelationObserver() {}
+
+}  // namespace syncer