Merge Compositor's ScrollbarAnimationControllers into single class

cc/input/scrollbar_animation_controller_thinning.h

-// 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.
-
-#ifndef CC_INPUT_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_
-#define CC_INPUT_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_
-
-#include <memory>
-
-#include "base/macros.h"
-#include "cc/base/cc_export.h"
-#include "cc/input/scrollbar_animation_controller.h"
-#include "cc/input/single_scrollbar_animation_controller_thinning.h"
-
-namespace cc {
-
-// This class fade in scrollbars when scroll and fade out after an idle delay.
-// The fade animations works on both scrollbars and is controlled in this class.
-
-// TODO(chaopeng) clean up the inheritance hierarchy after
-// ScrollbarAnimationControllerLinearFade merge into
-// ScrollbarAnimationControllerThinning so we can remove the empty overrides and
-// NOTREACHED() checks.
-class CC_EXPORT ScrollbarAnimationControllerThinning
-    : public ScrollbarAnimationController {
- public:
-  static std::unique_ptr<ScrollbarAnimationControllerThinning> Create(
-      int scroll_layer_id,
-      ScrollbarAnimationControllerClient* client,
-      base::TimeDelta delay_before_starting,
-      base::TimeDelta resize_delay_before_starting,
-      base::TimeDelta fade_duration,
-      base::TimeDelta thinning_duration);
-
-  ~ScrollbarAnimationControllerThinning() override;
-
-  void DidScrollUpdate(bool on_resize) override;
-  void DidScrollEnd() override;
-  bool ScrollbarsHidden() const override;
-
- protected:
-  bool NeedThinningAnimation() const override;
-
- private:
-  ScrollbarAnimationControllerThinning(
-      int scroll_layer_id,
-      ScrollbarAnimationControllerClient* client,
-      base::TimeDelta delay_before_starting,
-      base::TimeDelta resize_delay_before_starting,
-      base::TimeDelta fade_duration,
-      base::TimeDelta thinning_duration);
-
-  void ApplyOpacityToScrollbars(float opacity) override;
-  void RunAnimationFrame(float progress) override;
-  const base::TimeDelta& Duration() override;
-
-  float opacity_;
-  base::TimeDelta fade_duration_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScrollbarAnimationControllerThinning);
-};
-
-}  // namespace cc
-
-#endif  // CC_INPUT_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_