Make PriorityCompare a SMILAnimationSandwich detail

The ordering required in SMILTimeContainer::ApplyAnimationValues isn't
really the full-blown ordering used for sandwiches - using only the
"document order index" should be sufficient (although arguably still not
correct).

Bug: 998526
Change-Id: I293b9e55824c2b683b5991e7da3266958eb94e67
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1840991
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#703073}

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

@@ -31,6 +31,25 @@
 
 namespace blink {
 
+namespace {
+
+struct PriorityCompare {
+  PriorityCompare(SMILTime elapsed) : elapsed_(elapsed) {}
+  bool operator()(const Member<SVGSMILElement>& a,
+                  const Member<SVGSMILElement>& b) {
+    // FIXME: This should also consider possible timing relations between the
+    // elements.
+    SMILTime a_begin = a->BeginTimeForPrioritization(elapsed_);
+    SMILTime b_begin = b->BeginTimeForPrioritization(elapsed_);
+    if (a_begin == b_begin)
+      return a->DocumentOrderIndex() < b->DocumentOrderIndex();
+    return a_begin < b_begin;
+  }
+  SMILTime elapsed_;
+};
+
+}  // namespace
+
 SMILAnimationSandwich::SMILAnimationSandwich() = default;
 
 void SMILAnimationSandwich::Schedule(SVGSMILElement* animation) {

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

@@ -33,21 +33,6 @@
 
 namespace blink {
 
-struct PriorityCompare {
-  PriorityCompare(SMILTime elapsed) : elapsed_(elapsed) {}
-  bool operator()(const Member<SVGSMILElement>& a,
-                  const Member<SVGSMILElement>& b) {
-    // FIXME: This should also consider possible timing relations between the
-    // elements.
-    SMILTime a_begin = a->BeginTimeForPrioritization(elapsed_);
-    SMILTime b_begin = b->BeginTimeForPrioritization(elapsed_);
-    if (a_begin == b_begin)
-      return a->DocumentOrderIndex() < b->DocumentOrderIndex();
-    return a_begin < b_begin;
-  }
-  SMILTime elapsed_;
-};
-
 // This class implements/helps with implementing the "sandwich model" from SMIL.
 // https://www.w3.org/TR/SMIL3/smil-animation.html#animationNS-AnimationSandwichModel
 //

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

@@ -524,8 +524,13 @@ void SMILTimeContainer::ApplyAnimationValues(SMILTime elapsed) {
   // Everything bellow handles "discard" elements.
   UseCounter::Count(&GetDocument(), WebFeature::kSVGSMILAnimationAppliedEffect);
 
-  std::sort(animations_to_apply.begin(), animations_to_apply.end(),
-            PriorityCompare(elapsed));
+  // Sort by location in the document. (Should be based on the target rather
+  // than the timed element, but often enough they will order the same.)
+  std::sort(
+      animations_to_apply.begin(), animations_to_apply.end(),
+      [](const Member<SVGSMILElement>& a, const Member<SVGSMILElement>& b) {
+        return a->DocumentOrderIndex() < b->DocumentOrderIndex();
+      });
 
   for (const auto& timed_element : animations_to_apply) {
     if (timed_element->isConnected() && timed_element->IsSVGDiscardElement()) {