Animations: Allow document animation timelines to have a playback rate

Source/core/animation/AnimationTimeline.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 73 matching lines @@
     double currentTime(bool& isNull);
     double currentTime();
     double currentTimeInternal(bool& isNull);
     double currentTimeInternal();
     double effectiveTime();
     void pauseAnimationsForTesting(double);
 
     void setOutdatedAnimationPlayer(AnimationPlayer*);
     bool hasOutdatedAnimationPlayer() const;
 
+    void setPlaybackRate(double);
+    double playbackRate() const;
+
     Document* document() { return m_document.get(); }
 #if !ENABLE(OILPAN)
     void detachFromDocument();
 #endif
     void wake();
 
     void trace(Visitor*);
 
 protected:
     AnimationTimeline(Document*, PassOwnPtrWillBeRawPtr<PlatformTiming>);
 
 private:
     RawPtrWillBeMember<Document> m_document;
     double m_zeroTime;
     // AnimationPlayers which will be updated on the next frame
     // i.e. current, in effect, or had timing changed
     WillBeHeapHashSet<RefPtrWillBeMember<AnimationPlayer>> m_playersNeedingUpdate;
     WillBeHeapHashSet<RawPtrWillBeWeakMember<AnimationPlayer>> m_players;
 
+    double m_currentTimeSnapshot;
+    double m_rawCurrentTimeSnapshot;
+    double m_playbackRate;
+
     friend class SMILTimeContainer;
     static const double s_minimumDelay;
 
     OwnPtrWillBeMember<PlatformTiming> m_timing;
 
     class AnimationTimelineTiming final : public PlatformTiming {
     public:
         AnimationTimelineTiming(AnimationTimeline* timeline)
             : m_timeline(timeline)
             , m_timer(this, &AnimationTimelineTiming::timerFired)
@@ skipping 13 matching lines @@
         RawPtrWillBeMember<AnimationTimeline> m_timeline;
         Timer<AnimationTimelineTiming> m_timer;
     };
 
     friend class AnimationAnimationTimelineTest;
 };
 
 } // namespace blink
 
 #endif