Discard SampledEffects on elements if they are redundant

third_party/WebKit/Source/core/animation/AnimationStackTest.cpp

Index: third_party/WebKit/Source/core/animation/AnimationStackTest.cpp
diff --git a/third_party/WebKit/Source/core/animation/AnimationStackTest.cpp b/third_party/WebKit/Source/core/animation/AnimationStackTest.cpp
index 43067ee9031c2e8abf7cf49e177e7b67058ce3ea..195e051e19079efcde3fb65835c9d1a53790d1bd 100644
--- a/third_party/WebKit/Source/core/animation/AnimationStackTest.cpp
+++ b/third_party/WebKit/Source/core/animation/AnimationStackTest.cpp
@@ -40,6 +40,11 @@ protected:
         timeline->serviceAnimations(TimingUpdateForAnimationFrame);
     }
 
+    size_t sampledEffectCount()
+    {
+        return element->ensureElementAnimations().animationStack().m_sampledEffects.size();
+    }
+
     EffectModel* makeEffectModel(CSSPropertyID id, PassRefPtr<AnimatableValue> value)
     {
         AnimatableValueKeyframeVector keyframes(2);
@@ -127,4 +132,41 @@ TEST_F(AnimationAnimationStackTest, ClearedEffectsRemoved)
     EXPECT_EQ(0u, result.size());
 }
 
+TEST_F(AnimationAnimationStackTest, ForwardsFillDiscarding)
+{
+    play(makeKeyframeEffect(makeEffectModel(CSSPropertyFontSize, AnimatableDouble::create(1))), 2);
+    play(makeKeyframeEffect(makeEffectModel(CSSPropertyFontSize, AnimatableDouble::create(2))), 6);
+    play(makeKeyframeEffect(makeEffectModel(CSSPropertyFontSize, AnimatableDouble::create(3))), 4);
+    document->compositorPendingAnimations().update();
+    ActiveInterpolationsMap interpolations;
+
+    updateTimeline(11);
+    Heap::collectAllGarbage();
+    interpolations = AnimationStack::activeInterpolations(&element->elementAnimations()->animationStack(), nullptr, nullptr, KeyframeEffect::DefaultPriority);
+    EXPECT_EQ(1u, interpolations.size());
+    EXPECT_TRUE(interpolationValue(interpolations, CSSPropertyFontSize)->equals(AnimatableDouble::create(3).get()));
+    EXPECT_EQ(3u, sampledEffectCount());
+
+    updateTimeline(13);
+    Heap::collectAllGarbage();
+    interpolations = AnimationStack::activeInterpolations(&element->elementAnimations()->animationStack(), nullptr, nullptr, KeyframeEffect::DefaultPriority);
+    EXPECT_EQ(1u, interpolations.size());
+    EXPECT_TRUE(interpolationValue(interpolations, CSSPropertyFontSize)->equals(AnimatableDouble::create(3).get()));
+    EXPECT_EQ(3u, sampledEffectCount());
+
+    updateTimeline(15);
+    Heap::collectAllGarbage();
+    interpolations = AnimationStack::activeInterpolations(&element->elementAnimations()->animationStack(), nullptr, nullptr, KeyframeEffect::DefaultPriority);
+    EXPECT_EQ(1u, interpolations.size());
+    EXPECT_TRUE(interpolationValue(interpolations, CSSPropertyFontSize)->equals(AnimatableDouble::create(3).get()));
+    EXPECT_EQ(2u, sampledEffectCount());
+
+    updateTimeline(17);
+    Heap::collectAllGarbage();
+    interpolations = AnimationStack::activeInterpolations(&element->elementAnimations()->animationStack(), nullptr, nullptr, KeyframeEffect::DefaultPriority);
+    EXPECT_EQ(1u, interpolations.size());
+    EXPECT_TRUE(interpolationValue(interpolations, CSSPropertyFontSize)->equals(AnimatableDouble::create(3).get()));
+    EXPECT_EQ(1u, sampledEffectCount());
+}
+
 } // namespace blink