Move the update of the active state for SMIL out of UpdateTiming

This moves the call to SVGSMILElement::UpdateActiveState() from
SMILAnimationSandwich's UpdateTiming() method to UpdateSyncBases() and
renames the latter UpdateActiveStateAndOrder().
The reset of the |interval_has_changed_| flag is moved to
UpdateActiveState(), and SVGSMILElement::UpdateSyncBases() is
decommissioned.
This exposed that SVGSMILElement::UpdateInterval(...) could end up
clobbering |previous_interval_| when re-resolving the current interval.

Bug: 998526
Change-Id: I0b3787f93898b062a3a1e790bf761402c0515156
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1834351
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702353}

third_party/blink/renderer/core/svg/animation/smil_animation_sandwich.cc

@@ -60,7 +60,6 @@ void SMILAnimationSandwich::UpdateTiming(SMILTime elapsed) {
     if (!animation->CurrentIntervalIsActive(elapsed))
       continue;
     animation->UpdateInterval(elapsed);
-    animation->UpdateActiveState(elapsed);
   }
 }
 
@@ -86,13 +85,15 @@ SMILTime SMILAnimationSandwich::NextProgressTime(
   return earliest_progress_time;
 }
 
-void SMILAnimationSandwich::UpdateSyncBases(SMILTime elapsed) {
+void SMILAnimationSandwich::UpdateActiveStateAndOrder(
+    SMILTime presentation_time) {
   for (auto& animation : sandwich_)
-    animation->UpdateSyncBases();
+    animation->UpdateActiveState(presentation_time);
 
   if (!std::is_sorted(sandwich_.begin(), sandwich_.end(),
-                      PriorityCompare(elapsed))) {
-    std::sort(sandwich_.begin(), sandwich_.end(), PriorityCompare(elapsed));
+                      PriorityCompare(presentation_time))) {
+    std::sort(sandwich_.begin(), sandwich_.end(),
+              PriorityCompare(presentation_time));
   }
 }
 

third_party/blink/renderer/core/svg/animation/smil_animation_sandwich.h

@@ -105,8 +105,8 @@ struct PriorityCompare {
 //
 // UpdateTiming() handles updates to interval and transitions the active state.
 //
-// UpdateSyncBases() handles the sorting described above (as well notifying
-// about new intervals).
+// UpdateActiveStateAndOrder() handles the sorting described above and updates
+// the active state of the elements in the sandwich.
 //
 // UpdateActiveAnimationStack() constructs a vector containing only the active
 // elements.
@@ -123,9 +123,9 @@ class SMILAnimationSandwich : public GarbageCollected<SMILAnimationSandwich> {
   void Unschedule(SVGSMILElement* animation);
   void Reset();
 
-  void UpdateTiming(SMILTime elapsed);
-  void UpdateSyncBases(SMILTime elapsed);
-  void UpdateActiveAnimationStack(SMILTime elapsed);
+  void UpdateTiming(SMILTime presentation_time);
+  void UpdateActiveStateAndOrder(SMILTime presentation_time);
+  void UpdateActiveAnimationStack(SMILTime presentation_time);
   SVGSMILElement* ApplyAnimationValues();
 
   SMILTime NextInterestingTime(SMILTime presentation_time) const;

third_party/blink/renderer/core/svg/animation/smil_time_container.cc

@@ -489,7 +489,7 @@ void SMILTimeContainer::UpdateIntervals(SMILTime document_time) {
       sandwich->UpdateTiming(document_time);
 
     for (auto& sandwich : scheduled_animations_.Values())
-      sandwich->UpdateSyncBases(document_time);
+      sandwich->UpdateActiveStateAndOrder(document_time);
   } while (intervals_dirty_);
 }
 

third_party/blink/renderer/core/svg/animation/svg_smil_element.cc

@@ -934,7 +934,8 @@ void SVGSMILElement::UpdateInterval(SMILTime presentation_time) {
   SMILInterval next_interval = ResolveInterval(begin_after, presentation_time);
   if (!next_interval.IsResolved() || next_interval == interval_)
     return;
-  previous_interval_ = interval_;
+  if (interval_.IsResolved())
+    previous_interval_ = interval_;
   interval_ = next_interval;
   NotifyDependentsOnNewInterval(interval_);
   interval_has_changed_ = true;
@@ -1068,18 +1069,15 @@ bool SVGSMILElement::CurrentIntervalIsActive(SMILTime elapsed) {
   return true;
 }
 
-void SVGSMILElement::UpdateSyncBases() {
-  if (!interval_has_changed_)
-    return;
-  interval_has_changed_ = false;
-}
-
 void SVGSMILElement::UpdateActiveState(SMILTime elapsed) {
+  if (is_waiting_for_first_interval_)
+    return;
   const bool was_active = GetActiveState() == kActive;
   active_state_ = DetermineActiveState(elapsed);
   const bool is_active = GetActiveState() == kActive;
   const bool interval_restart =
       interval_has_changed_ && previous_interval_.end == interval_.begin;
+  interval_has_changed_ = false;
 
   if ((was_active && !is_active) || interval_restart) {
     ScheduleEvent(event_type_names::kEndEvent);

third_party/blink/renderer/core/svg/animation/svg_smil_element.h

@@ -88,7 +88,6 @@ class CORE_EXPORT SVGSMILElement : public SVGElement, public SVGTests {
   bool CurrentIntervalIsActive(SMILTime elapsed);
   void UpdateInterval(SMILTime presentation_time);
   void UpdateActiveState(SMILTime elapsed);
-  void UpdateSyncBases();
 
   SMILTime NextInterestingTime(SMILTime elapsed) const;
   SMILTime NextProgressTime(SMILTime elapsed) const;