Implement frames() timing function

cc/animation/keyframed_animation_curve_unittest.cc

Index: cc/animation/keyframed_animation_curve_unittest.cc
diff --git a/cc/animation/keyframed_animation_curve_unittest.cc b/cc/animation/keyframed_animation_curve_unittest.cc
index df3a0b1e7551f3ecb40487ead300173d75ca9f81..c050404d7143584645a08d11d96c3b98c3c83be5 100644
--- a/cc/animation/keyframed_animation_curve_unittest.cc
+++ b/cc/animation/keyframed_animation_curve_unittest.cc
@@ -535,6 +535,30 @@ TEST(KeyframedAnimationCurveTest, StepsTimingFunctionStepAtEnd) {
   }
 }
 
+// Tests a frames timing function.
+TEST(KeyframedAnimationCurveTest, FramesTimingFunction) {
+  std::unique_ptr<KeyframedFloatAnimationCurve> curve(
+      KeyframedFloatAnimationCurve::Create());
+  curve->AddKeyframe(FloatKeyframe::Create(base::TimeDelta(), 0.f,
+                                           FramesTimingFunction::Create(5)));
+  curve->AddKeyframe(
+      FloatKeyframe::Create(base::TimeDelta::FromSecondsD(1.0), 1.f, nullptr));
+
+  struct Expected {
+    double time;
+    float value;
+  } expectations[] = {
+      {0.0, 0.f},     {0.1999, 0.f},  {0.2001, 0.25f}, {0.3999, 0.25f},
+      {0.4001, 0.5f}, {0.5999, 0.5f}, {0.6001, 0.75f}, {0.7999, 0.75f},
+      {0.8001, 1.f},  {1.0, 1.f},
+  };
+  for (const auto& expectation : expectations) {
+    EXPECT_FLOAT_EQ(
+        expectation.value,
+        curve->GetValue(base::TimeDelta::FromSecondsD(expectation.time)));
+  }
+}
+
 // Tests that animated bounds are computed as expected.
 TEST(KeyframedAnimationCurveTest, AnimatedBounds) {
   std::unique_ptr<KeyframedTransformAnimationCurve> curve(
@@ -851,6 +875,23 @@ TEST(KeyframedAnimationCurveTest, StepsTimingEndInputsOutsideZeroOneRange) {
   EXPECT_FLOAT_EQ(2.f, curve->GetValue(base::TimeDelta::FromSecondsD(0.75f)));
 }
 
+// Tests that a frames timing function works as expected for inputs outside of
+// range [0,1]
+TEST(KeyframedAnimationCurveTest, FramesTimingInputsOutsideZeroOneRange) {
+  std::unique_ptr<KeyframedFloatAnimationCurve> curve(
+      KeyframedFloatAnimationCurve::Create());
+  curve->AddKeyframe(FloatKeyframe::Create(base::TimeDelta(), 0.f,
+                                           FramesTimingFunction::Create(5)));
+  curve->AddKeyframe(
+      FloatKeyframe::Create(base::TimeDelta::FromSecondsD(1.0), 2.f, nullptr));
+  // Curve timing function producing timing outputs outside of range [0,1].
+  curve->SetTimingFunction(
+      CubicBezierTimingFunction::Create(0.5f, -0.5f, 0.5f, 1.5f));
+
+  EXPECT_FLOAT_EQ(-0.5f, curve->GetValue(base::TimeDelta::FromSecondsD(0.25f)));
+  EXPECT_FLOAT_EQ(2.5f, curve->GetValue(base::TimeDelta::FromSecondsD(0.75f)));
+}
+
 // Tests that an animation with a curve timing function and multiple keyframes
 // works as expected.
 TEST(KeyframedAnimationCurveTest, CurveTimingMultipleKeyframes) {