Web Animations: Introduce ActiveAnimations and AnimationStack

Source/core/animation/DocumentTimeline.h

Index: Source/core/animation/DocumentTimeline.h
diff --git a/Source/core/animation/DocumentTimeline.h b/Source/core/animation/DocumentTimeline.h
index a2bd963f0bda4d5263b09db30bdaeecfc90a2a07..9093b3d6c3350d3a845224f86fe6db937d97cbd3 100644
--- a/Source/core/animation/DocumentTimeline.h
+++ b/Source/core/animation/DocumentTimeline.h
@@ -31,7 +31,9 @@
 #ifndef DocumentTimeline_h
 #define DocumentTimeline_h
 
+#include "core/animation/ActiveAnimations.h"
 #include "core/animation/Player.h"
+#include "core/dom/Element.h"
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
@@ -50,6 +52,13 @@ public:
     PassRefPtr<Player> play(TimedItem*);
     double currentTime() { return m_currentTime; }
     void pauseAnimationsForTesting(double);
+    AnimationStack* animationStack(const Element* element) const
+    {
+        if (!element->activeAnimations())
+            return 0;
+        return element->activeAnimations()->defaultStack();

[esprehn, 2013/07/23 01:20:38]

if (ActiveAnimations* animations = element->activeAnimations())
  return animations->defaultStack();
return 0;

That pattern is good because if you make activeAnimations more expensive in the
future (ex. hash maps) we don't call it all over.

[dstockwell, 2013/07/23 01:33:00]

Done.

+    }
+    AnimationStack* ensureAnimationStack(Element* element) { return element->ensureActiveAnimations()->defaultStack(); }

[esprehn, 2013/07/23 01:20:38]

Remove this method, just call this directly or put an inline method in your .cpp
file. This certainly doesn't need to be an instance method. :)

[dstockwell, 2013/07/23 01:33:00]

Removed.

The plan was for this to become virtual once there were multiple timelines bound
to different stacks inside ActiveAnimations. But I'll add it back at that point
if necessary.

 
 private:
     DocumentTimeline(Document*);