Web Animations: Fix Player's timing update when source content becomes longer

Source/core/animation/AnimationPlayer.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 148 matching lines @@
 
     if (outdated) {
         setOutdated();
     }
 }
 
 // Update timing to reflect updated animation clock due to tick
 void AnimationPlayer::updateCurrentTimingState(TimingUpdateReason reason)
 {
     if (m_held) {
-        // Add hystersis due to floating point error accumulation
-        if (!isNull(m_startTime) && m_timeline && !limited(calculateCurrentTime() + 0.001 * m_playbackRate) && playStateInternal() == Finished) {
-            m_held = false;
-            setCurrentTimeInternal(calculateCurrentTime(), reason);
-            return;
+        double newCurrentTime = m_holdTime;
+        if (playStateInternal() == Finished && !isNull(m_startTime) && m_timeline) {
+            // Add hystersis due to floating point error accumulation
+            if (!limited(calculateCurrentTime() + 0.001 * m_playbackRate)) {
+                // The current time became unlimited, eg. due to a backwards
+                // seek of the timeline.
+                newCurrentTime = calculateCurrentTime();
+            } else if (!limited(m_holdTime)) {
+                // The hold time became unlimited, eg. due to the source content
+                // becoming longer.
+                newCurrentTime = clampTo<double>(calculateCurrentTime(), 0, sourceEnd());
+            }
         }
-        setCurrentTimeInternal(m_holdTime, reason);
-        return;
+        setCurrentTimeInternal(newCurrentTime, reason);
+    } else if (limited(calculateCurrentTime())) {
+        m_held = true;
+        m_holdTime = m_playbackRate < 0 ? 0 : sourceEnd();
     }
-    if (!limited(calculateCurrentTime()))
-        return;
-    m_held = true;
-    m_holdTime = m_playbackRate < 0 ? 0 : sourceEnd();
 }
 
 double AnimationPlayer::startTime(bool& isNull) const
 {
     double result = startTime();
     isNull = std::isnan(result);
     return result;
 }
 
 double AnimationPlayer::startTime() const
@@ skipping 23 matching lines @@
 double AnimationPlayer::currentTimeInternal() const
 {
     double result = m_held ? m_holdTime : calculateCurrentTime();
 #if ENABLE(ASSERT)
     const_cast<AnimationPlayer*>(this)->updateCurrentTimingState(TimingUpdateOnDemand);
     ASSERT(result == (m_held ? m_holdTime : calculateCurrentTime()));
 #endif
     return result;
 }
 
+double AnimationPlayer::unlimitedCurrentTimeInternal() const
+{
+#if ENABLE(ASSERT)
+    currentTimeInternal();
+#endif
+    return playStateInternal() == Paused || isNull(m_startTime)
+        ? currentTimeInternal()
+        : calculateCurrentTime();
+}
+
 void AnimationPlayer::preCommit(int compositorGroup, bool startOnCompositor)
 {
     PlayStateUpdateScope updateScope(*this, TimingUpdateOnDemand, DoNotSetCompositorPending);
 
     bool softChange = m_compositorState && (paused() || m_compositorState->playbackRate != m_playbackRate);
     bool hardChange = m_compositorState && (m_compositorState->sourceChanged || m_compositorState->startTime != m_startTime);
 
     // FIXME: softChange && !hardChange should generate a Pause/ThenStart,
     // not a Cancel, but we can't communicate these to the compositor yet.
 
@@ skipping 695 matching lines @@
     visitor->trace(m_content);
     visitor->trace(m_timeline);
     visitor->trace(m_pendingFinishedEvent);
     visitor->trace(m_finishedPromise);
     visitor->trace(m_readyPromise);
     EventTargetWithInlineData::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace