Revert 171714 - Use an auxiliary list of animation controllers.

cc/animation_registrar.h

-// Copyright 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 CC_ANIMATION_REGISTRAR_H_
-#define CC_ANIMATION_REGISTRAR_H_
-
-namespace cc {
-
-class LayerAnimationController;
-
-// TODO(vollick): we need to rename:
-//    AnimationRegistrar -> AnimationController
-//    LayerAnimationController -> LayerAnimator
-class CC_EXPORT AnimationRegistrar {
- public:
-  // Registers the given animation controller as active. An active animation
-  // controller is one that has a running animation that needs to be ticked.
-  virtual void DidActivateAnimationController(LayerAnimationController*) = 0;
-
-  // Unregisters the given animation controller. When this happens, the
-  // animation controller will no longer be ticked (since it's not active). It
-  // is not an error to call this function with a deactivated controller.
-  virtual void DidDeactivateAnimationController(LayerAnimationController*) = 0;
-
-  // Registers the given controller as alive.
-  virtual void RegisterAnimationController(LayerAnimationController*) = 0;
-
-  // Unregisters the given controller as alive.
-  virtual void UnregisterAnimationController(LayerAnimationController*) = 0;
-};
-
-}  // namespace cc
-
-#endif  // CC_ANIMATION_REGISTRAR_H_