Add the owning_element to CSSAnimation class

The patch adds owning_element to CSSAnimation class. Now the
CSSAnimations have an owning_element and we will clear the owning
element if the animation disassociate from the owning_element.

The next follow up patches will add the owning_element to CSSTransition
and using owning element to compare the composite ordering.

As per spec: https://drafts.csswg.org/css-transitions-2/#owning-element
and: https://drafts.csswg.org/css-animations-2/#owning-element-section

Bug: 1047316

Change-Id: I5ddb54b13330f851b830547f02d9acaad91f3e1d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2108613
Commit-Queue: Hao Sheng <haozhes@chromium.org>
Reviewed-by: Majid Valipour <majidvp@chromium.org>
Reviewed-by: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753507}

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

@@ -124,7 +124,7 @@ Animation::AnimationClassPriority AnimationPriority(
   Animation::AnimationClassPriority priority;
   if (animation.IsCSSTransition())
     priority = Animation::AnimationClassPriority::kCssTransitionPriority;
-  else if (animation.IsCSSAnimation())
+  else if (animation.IsCSSAnimation() && animation.IsOwned())
     priority = Animation::AnimationClassPriority::kCssAnimationPriority;
   else
     priority = Animation::AnimationClassPriority::kDefaultPriority;

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

@@ -119,6 +119,9 @@ class CORE_EXPORT Animation : public EventTargetWithInlineData,
 
   virtual bool IsCSSAnimation() const { return false; }
   virtual bool IsCSSTransition() const { return false; }
+  virtual Element* OwningElemnt() const { return nullptr; }
+  virtual void ClearOwningElement() {}
+  bool IsOwned() const { return !OwningElemnt(); }
 
   // Returns whether the animation is finished.
   bool Update(TimingUpdateReason);

third_party/blink/renderer/core/animation/css/css_animation.cc

@@ -3,9 +3,9 @@
 // found in the LICENSE file.
 
 #include "third_party/blink/renderer/core/animation/css/css_animation.h"
-
 #include "third_party/blink/renderer/core/animation/animation.h"
 #include "third_party/blink/renderer/core/animation/css/css_animations.h"
+#include "third_party/blink/renderer/core/animation/keyframe_effect.h"
 #include "third_party/blink/renderer/core/dom/document.h"
 
 namespace blink {
@@ -16,7 +16,12 @@ CSSAnimation::CSSAnimation(ExecutionContext* execution_context,
                            const String& animation_name)
     : Animation(execution_context, timeline, content),
       animation_name_(animation_name),
-      ignore_css_play_state_(false) {}
+      ignore_css_play_state_(false) {
+  // The owning_element does not always equal to the target element of an
+  // animation. The following spec gives an example:
+  // https://drafts.csswg.org/css-animations-2/#owning-element-section
+  owning_element_ = To<KeyframeEffect>(effect())->target();
+}
 
 String CSSAnimation::playState() const {
   FlushStyles();

third_party/blink/renderer/core/animation/css/css_animation.h

@@ -8,6 +8,7 @@
 #include "third_party/blink/renderer/bindings/core/v8/script_promise.h"
 #include "third_party/blink/renderer/core/animation/animation.h"
 #include "third_party/blink/renderer/core/core_export.h"
+#include "third_party/blink/renderer/core/dom/element.h"
 
 namespace blink {
 
@@ -22,6 +23,9 @@ class CORE_EXPORT CSSAnimation : public Animation {
 
   bool IsCSSAnimation() const final { return true; }
 
+  void ClearOwningElement() final { owning_element_ = nullptr; }
+  Element* OwningElement() const { return owning_element_; }
+
   const String& animationName() const { return animation_name_; }
 
   // Animation overrides.
@@ -48,6 +52,10 @@ class CORE_EXPORT CSSAnimation : public Animation {
   // https://drafts.csswg.org/css-animations-2/#interaction-between-animation-play-state-and-web-animations-API
   bool getIgnoreCSSPlayState() { return ignore_css_play_state_; }
   void resetIgnoreCSSPlayState() { ignore_css_play_state_ = false; }
+  void Trace(blink::Visitor* visitor) override {
+    Animation::Trace(visitor);
+    visitor->Trace(owning_element_);
+  }
 
  protected:
   AnimationEffect::EventDelegate* CreateEventDelegate(
@@ -74,6 +82,10 @@ class CORE_EXPORT CSSAnimation : public Animation {
   // When set, the web-animation API is overruling the animation-play-state
   // style.
   bool ignore_css_play_state_;
+  // The owning element of an animation refers to the element or pseudo-element
+  // whose animation-name property was applied that generated the animation
+  // The spec: https://drafts.csswg.org/css-animations-2/#owning-element-section
+  Member<Element> owning_element_;
 };
 
 template <>

third_party/blink/renderer/core/animation/css/css_animations.cc

@@ -558,6 +558,7 @@ void CSSAnimations::MaybeApplyPendingUpdate(Element* element) {
            cancelled_indices[i] < cancelled_indices[i + 1]);
     Animation& animation =
         *running_animations_[cancelled_indices[i]]->animation;
+    animation.ClearOwningElement();
     animation.cancel();
     animation.Update(kTimingUpdateOnDemand);
     running_animations_.EraseAt(cancelled_indices[i]);