Blink Compositor Animation: Introduce CompositorAnimationHost correctly.

third_party/WebKit/Source/platform/animation/CompositorAnimationHost.h

 // Copyright 2016 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 CompositorAnimationHost_h
 #define CompositorAnimationHost_h
 
-#include "base/memory/ref_counted.h"
-#include "cc/animation/animation_host.h"
 #include "platform/PlatformExport.h"
+#include "platform/graphics/CompositorElementId.h"
 #include "ui/gfx/geometry/vector2d.h"
 #include "wtf/Noncopyable.h"
 
-#include <memory>
+namespace cc {
+class AnimationHost;
+}
 
 namespace blink {
 
+class CompositorAnimationTimeline;
+
 // A compositor representation for cc::AnimationHost.
-// This class wraps cc::AnimationHost and is currently only created from
-// CompositorAnimationTimeline::compositorAnimationHost.
-// TODO(ymalik): Correctly introduce CompositorAnimationHost to blink. See
-// crbug.com/610763.
 class PLATFORM_EXPORT CompositorAnimationHost {
+  WTF_MAKE_NONCOPYABLE(CompositorAnimationHost);
+
  public:
   explicit CompositorAnimationHost(cc::AnimationHost*);
 
-  // TODO(ymalik): Remove when CompositorAnimationHost* optional nullable ptr
-  // is returned. See crbug.com/610763.
-  bool isNull() const;
+  void addTimeline(CompositorAnimationTimeline*);

[jbroman, 2016/12/13 16:38:32]

These look like they could take "const CompositorAnimationTimeline&". Any reason
to take non-const pointers?

[loyso (OOO), 2016/12/13 22:23:35]

Yes, technically we can. Only because 'const' semantics is shallow in C++.
I would be different to cc where we add/remove timelines to a non-const list of
timelines.

[loyso (OOO), 2016/12/19 04:03:12]

Done.

+  void removeTimeline(CompositorAnimationTimeline*);
 
-  void adjustImplOnlyScrollOffsetAnimation(cc::ElementId,
+  void adjustImplOnlyScrollOffsetAnimation(CompositorElementId,
                                            const gfx::Vector2dF& adjustment);
-  void takeOverImplOnlyScrollOffsetAnimation(cc::ElementId);
+  void takeOverImplOnlyScrollOffsetAnimation(CompositorElementId);
 
  private:
   cc::AnimationHost* m_animationHost;
 };
 
 }  // namespace blink
 
 #endif  // CompositorAnimationTimeline_h