Web Animations: Fix CSS events to handle animations with very short durations

Source/core/animation/css/CSSAnimations.cpp

 /*
  * 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 173 matching lines @@
             }
 
             KeyframeAnimationEffect::KeyframeVector keyframes;
             element->document()->styleResolver()->resolveKeyframes(element, style, animationName.impl(), keyframes);
             if (!keyframes.isEmpty()) {
                 Timing timing;
                 timingFromAnimationData(animationData, timing);
                 OwnPtr<CSSAnimations::EventDelegate> eventDelegate = adoptPtr(new EventDelegate(element, animationName));
                 ASSERT(!isNull(element->document()->timeline()->currentTime()));
                 // FIXME: crbug.com/268791 - Keyframes are already normalized, perhaps there should be a flag on KeyframeAnimationEffect to skip normalization.
-                m_animations.set(animationName.impl(), element->document()->timeline()->play(
-                    Animation::create(element, KeyframeAnimationEffect::create(keyframes), timing, eventDelegate.release()).get()).get());
+                RefPtr<Animation> animation = Animation::create(element, KeyframeAnimationEffect::create(keyframes), timing, eventDelegate.release());
+                // If the start delay is zero, force a sample to make sure events fire.
+                if (!timing.startDelay)
+                    animation->forceSampleBeforeStartTime();
+                m_animations.set(animationName.impl(), element->document()->timeline()->play(animation.get()).get());
             }
         }
     }
 
     for (HashSet<StringImpl*>::const_iterator iter = inactive.begin(); iter != inactive.end(); ++iter)
         m_animations.take(*iter)->cancel();
 }
 
 void CSSAnimations::cancel()
 {
     for (AnimationMap::iterator iter = m_animations.begin(); iter != m_animations.end(); ++iter)
         iter->value->cancel();
 
     m_animations.clear();
 }
 
 void CSSAnimations::EventDelegate::maybeDispatch(Document::ListenerType listenerType, AtomicString& eventName, double elapsedTime)
 {
     if (m_target->document()->hasListenerType(listenerType))
         m_target->document()->timeline()->addEventToDispatch(m_target, AnimationEvent::create(eventName, m_name, elapsedTime));
 }
 
-void CSSAnimations::EventDelegate::onEventCondition(bool wasInPlay, bool isInPlay, double previousIteration, double currentIteration)
+void CSSAnimations::EventDelegate::onEventCondition(bool wasInPlay, bool isInPlay, bool wasCurrent, bool isCurrent, double previousIteration, double currentIteration)
 {
     // Events for a single document are queued and dispatched as a group at
     // the end of DocumentTimeline::serviceAnimations.
     // FIXME: Events which are queued outside of serviceAnimations should
     // trigger a timer to dispatch when control is released.
     // FIXME: Receive TimedItem as param in order to produce correct elapsed time value.
     double elapsedTime = 0;
-    if (!wasInPlay && isInPlay) {
-        maybeDispatch(Document::ANIMATIONSTART_LISTENER, eventNames().webkitAnimationStartEvent, elapsedTime);
-        return;
-    }
     if (wasInPlay && isInPlay && currentIteration != previousIteration) {
         maybeDispatch(Document::ANIMATIONITERATION_LISTENER, eventNames().webkitAnimationIterationEvent, elapsedTime);
         return;
     }
-    if (wasInPlay && !isInPlay) {
+    bool wasBefore = !wasInPlay && wasCurrent;
+    bool isBefore = !isInPlay && isCurrent;
+    if (wasBefore && !isBefore)
+        maybeDispatch(Document::ANIMATIONSTART_LISTENER, eventNames().webkitAnimationStartEvent, elapsedTime);
+    bool wasAfter = !wasInPlay && !wasCurrent;
+    bool isAfter = !isInPlay && !isCurrent;
+    if (!wasAfter && isAfter)
         maybeDispatch(Document::ANIMATIONEND_LISTENER, eventNames().webkitAnimationEndEvent, elapsedTime);
-        return;
-    }
 }
 
 } // namespace WebCore