Bug 1479173 - Check animation generation change in the mProperties loop and drop LayerAnimationInfo::sRecords loop. r=birtles

If mIsRunningOnCompositor is true, the property is effective state because
CanThrottle() is called in advance of a restyle for the effect so that we can
drop the check and drop skipping in the case of non-effective properties.

Depends on D10694

Differential Revision: https://phabricator.services.mozilla.com/D10695

dom/animation/KeyframeEffect.cpp

@@ -1242,23 +1242,18 @@ KeyframeEffect::CanThrottle() const
     return true;
   }
 
+  EffectSet* effectSet = nullptr;
   for (const AnimationProperty& property : mProperties) {
     if (!property.mIsRunningOnCompositor) {
       return false;
     }
-  }
 
-  EffectSet* effectSet = nullptr;
-  for (const LayerAnimationInfo::Record& record :
-        LayerAnimationInfo::sRecords) {
-    // Skip properties that are overridden by !important rules.
-    // (GetEffectiveAnimationOfProperty, as called by
-    // HasEffectiveAnimationOfProperty, only returns a property which is
-    // neither overridden by !important rules nor overridden by other
-    // animation.)
-    if (!HasEffectiveAnimationOfProperty(record.mProperty)) {
-      continue;
-    }
+    MOZ_ASSERT(nsCSSPropertyIDSet::CompositorAnimatables()
+                 .HasProperty(property.mProperty),
+               "The property should be able to run on the compositor");
+    MOZ_ASSERT(HasEffectiveAnimationOfProperty(property.mProperty),
+               "There should be an effective animation of the property while "
+               "it is marked as being run on the compositor");
 
     if (!effectSet) {
       effectSet = EffectSet::GetEffectSet(mTarget->mElement,
@@ -1266,10 +1261,14 @@ KeyframeEffect::CanThrottle() const
       MOZ_ASSERT(effectSet, "CanThrottle should be called on an effect "
                             "associated with a target element");
     }
+
+    DisplayItemType displayItemType =
+      LayerAnimationInfo::GetDisplayItemTypeForProperty(property.mProperty);
+
     // Note that AnimationInfo::GetGenarationFromFrame() is supposed to work
     // with the primary frame instead of the style frame.
     Maybe<uint64_t> generation = layers::AnimationInfo::GetGenerationFromFrame(
-        GetPrimaryFrame(), record.mDisplayItemType);
+        GetPrimaryFrame(), displayItemType);
     // Unthrottle if the animation needs to be brought up to date
     if (!generation || effectSet->GetAnimationGeneration() != *generation) {
       return false;

layout/style/LayerAnimationInfo.cpp

@@ -19,6 +19,20 @@ namespace mozilla {
       DisplayItemType::TYPE_OPACITY,
       nsChangeHint_UpdateOpacityLayer } };
 
+/* static */ DisplayItemType
+LayerAnimationInfo::GetDisplayItemTypeForProperty(nsCSSPropertyID aProperty)
+{
+  switch (aProperty) {
+    case eCSSProperty_opacity:
+      return DisplayItemType::TYPE_OPACITY;
+    case eCSSProperty_transform:
+      return DisplayItemType::TYPE_TRANSFORM;
+    default:
+      break;
+  }
+  return DisplayItemType::TYPE_ZERO;
+}
+
 #ifdef DEBUG
 /* static */ void
 LayerAnimationInfo::Initialize()
@@ -49,6 +63,10 @@ LayerAnimationInfo::Initialize()
       MOZ_ASSERT(found,
                  "CSS property with the CSSPropFlags::CanAnimateOnCompositor "
                  "flag does not have an entry in LayerAnimationInfo::sRecords");
+      MOZ_ASSERT(GetDisplayItemTypeForProperty(prop) !=
+                   DisplayItemType::TYPE_ZERO,
+                 "GetDisplayItemTypeForProperty should return a valid display "
+                 "item type");
     }
   }
   MOZ_ASSERT(properties.Equals(nsCSSPropertyIDSet::CompositorAnimatables()));

layout/style/LayerAnimationInfo.h

@@ -26,6 +26,13 @@ struct LayerAnimationInfo {
     nsChangeHint mChangeHint;
   };
 
+  // Returns the corresponding display item type for |aProperty| when it is
+  // animated on the compositor.
+  // Returns DisplayItemType::TYPE_ZERO if |aProperty| cannot be animated on the
+  // compositor.
+  static DisplayItemType
+  GetDisplayItemTypeForProperty(nsCSSPropertyID aProperty);
+
   static const size_t kRecords =
     nsCSSPropertyIDSet::CompositorAnimatableCount();
   static const Record sRecords[kRecords];