Introduce a layering in the invalidation component as public and impl

components/invalidation/ticl_settings_provider.h

-// Copyright 2014 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 COMPONENTS_INVALIDATION_TICL_SETTINGS_PROVIDER_H_
-#define COMPONENTS_INVALIDATION_TICL_SETTINGS_PROVIDER_H_
-
-#include "base/macros.h"
-#include "base/observer_list.h"
-
-namespace invalidation {
-
-// Provides configuration settings to TiclInvalidationService and notifies it
-// when the settings change.
-class TiclSettingsProvider {
- public:
-  class Observer {
-   public:
-    virtual void OnUseGCMChannelChanged() = 0;
-
-   protected:
-    virtual ~Observer();
-  };
-
-  TiclSettingsProvider();
-  virtual ~TiclSettingsProvider();
-
-  virtual bool UseGCMChannel() const = 0;
-
-  void AddObserver(Observer* observer);
-  void RemoveObserver(Observer* observer);
-
- protected:
-  void FireOnUseGCMChannelChanged();
-
- private:
-  base::ObserverList<Observer, true> observers_;
-
-  DISALLOW_COPY_AND_ASSIGN(TiclSettingsProvider);
-};
-
-}  // namespace invalidation
-
-#endif  // COMPONENTS_INVALIDATION_TICL_SETTINGS_PROVIDER_H_