Web Animations: Timeline should not advance during task execution

Source/core/animation/AnimationClock.h

Index: Source/core/animation/AnimationClock.h
diff --git a/Source/core/animation/AnimationClock.h b/Source/core/animation/AnimationClock.h
index 540dfbeb2ebd126188b648a079d5a337dfb46ee1..d5ffead49de6619a07c00cdd2bf236635bdcb85d 100644
--- a/Source/core/animation/AnimationClock.h
+++ b/Source/core/animation/AnimationClock.h
@@ -31,40 +31,31 @@
 #ifndef AnimationClock_h
 #define AnimationClock_h
 
-#include "wtf/CurrentTime.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace WebCore {
 
-// FIXME: This value is used to suppress updates when time is required outside of a frame.
-// The purpose of allowing the clock to update during such periods is to allow animations
-// to have an appropriate start time and for getComputedStyle to attempt to catch-up to a
-// compositor animation. However a more accurate system might be to attempt to phase-lock
-// with the frame clock.
-const double minTimeBeforeUnsynchronizedAnimationClockTick = 0.005;
-
 class AnimationClock {
 public:
-    static PassOwnPtr<AnimationClock> create(WTF::TimeFunction monotonicallyIncreasingTime = WTF::monotonicallyIncreasingTime)
+    AnimationClock()
+        : m_time(0)
     {
-        return adoptPtr(new AnimationClock(monotonicallyIncreasingTime));
     }
 
     void updateTime(double time);
     double currentTime();
-    void unfreeze() { m_frozen = false; }
-    void resetTimeForTesting() { m_time = 0; m_frozen = true; }
+    void resetTimeForTesting() { m_time = 0; taskTime() = 0; }
 
-private:
-    AnimationClock(WTF::TimeFunction monotonicallyIncreasingTime)
-        : m_monotonicallyIncreasingTime(monotonicallyIncreasingTime)
-        , m_time(0)
-        , m_frozen(false)
+    static double& taskTime()

[shans, 2014/04/30 20:43:07]

I think this needs a comment indicating its purpose

[esprehn, 2014/04/30 22:43:50]

Can we use a regular getter/setter pair instead of returning the number by
reference?

[dstockwell, 2014/04/30 22:59:51]

It's a static local, I can't access it from two different methods. It doesn't
need to be local if there's a good place to initialize it once. Is there?

[esprehn, 2014/04/30 23:54:33]

Don't use a static local, make it a static member of the AnimationClock and
initialize it in the cpp file. Then put the getter and setter here.

     {
+        static double time = 0;
+        return time;
     }
-    WTF::TimeFunction m_monotonicallyIncreasingTime;
+
+    static void notifyTaskStartTime(double time) { taskTime() = time; }
+
+private:
     double m_time;
-    bool m_frozen;
 };
 
 } // namespace WebCore