[Sync] Refactor sync configuration logic.

sync/test/callback_counter.h

+// Copyright (c) 2012 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.
+
+#ifndef SYNC_TEST_CALLBACK_COUNTER_H_
+#define SYNC_TEST_CALLBACK_COUNTER_H_
+#pragma once
+
+namespace browser_sync {
+
+// Helper class to track how many times a callback is triggered.
+class CallbackCounter {
+ public:
+  CallbackCounter() { Reset(); }
+  ~CallbackCounter() {}
+
+  void Reset() { times_called_ = 0; }
+  void Callback() { ++times_called_; }
+  int times_called() const { return times_called_; }
+
+ private:
+  int times_called_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallbackCounter);
+};
+
+}  // namespace browser_sync
+
+#endif  // SYNC_TEST_CALLBACK_COUNTER_H_