Tweak the math in ScrollOffsetAnimationCurve::UpdateTarget.

cc/animation/scroll_offset_animation_curve_unittest.cc

Index: cc/animation/scroll_offset_animation_curve_unittest.cc
diff --git a/cc/animation/scroll_offset_animation_curve_unittest.cc b/cc/animation/scroll_offset_animation_curve_unittest.cc
index 4638ecfbfb0ea2f9066c29ab9eb0af8b33601f26..7044b03addae2ce538a69a0ab4986bc399fbf22c 100644
--- a/cc/animation/scroll_offset_animation_curve_unittest.cc
+++ b/cc/animation/scroll_offset_animation_curve_unittest.cc
@@ -128,64 +128,29 @@ TEST(ScrollOffsetAnimationCurveTest, UpdateTarget) {
   gfx::ScrollOffset initial_value(0.f, 0.f);
   gfx::ScrollOffset target_value(0.f, 3600.f);
   scoped_ptr<ScrollOffsetAnimationCurve> curve(
-      ScrollOffsetAnimationCurve::Create(target_value,
-                                         EaseInOutTimingFunction::Create()));
-  curve->SetInitialValue(initial_value);
-  EXPECT_EQ(1.0, curve->Duration().InSecondsF());
-  EXPECT_EQ(1800.0, curve->GetValue(base::TimeDelta::FromSecondsD(0.5)).y());
-  EXPECT_EQ(3600.0, curve->GetValue(base::TimeDelta::FromSecondsD(1.0)).y());
-
-  curve->UpdateTarget(0.5, gfx::ScrollOffset(0.0, 9900.0));
-
-  EXPECT_EQ(2.0, curve->Duration().InSecondsF());
-  EXPECT_EQ(1800.0, curve->GetValue(base::TimeDelta::FromSecondsD(0.5)).y());
-  EXPECT_NEAR(5410.05, curve->GetValue(base::TimeDelta::FromSecondsD(1.0)).y(),
-              0.01);
-  EXPECT_EQ(9900.0, curve->GetValue(base::TimeDelta::FromSecondsD(2.0)).y());
-
-  curve->UpdateTarget(1.0, gfx::ScrollOffset(0.0, 7200.0));
-
-  EXPECT_NEAR(1.705, curve->Duration().InSecondsF(), 0.01);
-  EXPECT_NEAR(5410.05, curve->GetValue(base::TimeDelta::FromSecondsD(1.0)).y(),
-              0.01);
-  EXPECT_EQ(7200.0, curve->GetValue(base::TimeDelta::FromSecondsD(1.705)).y());
-}
-
-TEST(ScrollOffsetAnimationCurveTest, UpdateTargetWithLargeVelocity) {
-  gfx::ScrollOffset initial_value(0.f, 0.f);
-  gfx::ScrollOffset target_value(0.f, 900.f);
-  scoped_ptr<ScrollOffsetAnimationCurve> curve(
-      ScrollOffsetAnimationCurve::Create(target_value,
-                                         EaseInOutTimingFunction::Create()));
-  curve->SetInitialValue(initial_value);
-  EXPECT_EQ(0.5, curve->Duration().InSecondsF());
-
-  EXPECT_EQ(450.0, curve->GetValue(base::TimeDelta::FromSecondsD(0.25)).y());
-
-  // This leads to a new computed velocity larger than 5000.
-  curve->UpdateTarget(0.25, gfx::ScrollOffset(0.0, 450.0001));
-
-  EXPECT_NEAR(0.25015, curve->Duration().InSecondsF(), 0.0001);
-  EXPECT_NEAR(450.0,
-              curve->GetValue(base::TimeDelta::FromSecondsD(0.22501)).y(),
-              0.001);
-  EXPECT_NEAR(450.0,
-              curve->GetValue(base::TimeDelta::FromSecondsD(0.225015)).y(),
-              0.001);
-}
-
-TEST(ScrollOffsetAnimationCurveTest, UpdateTargetConstantDuration) {
-  gfx::ScrollOffset initial_value(0.f, 0.f);
-  gfx::ScrollOffset target_value(0.f, 3600.f);
-  scoped_ptr<ScrollOffsetAnimationCurve> curve(
       ScrollOffsetAnimationCurve::Create(
           target_value, EaseInOutTimingFunction::Create(),
           ScrollOffsetAnimationCurve::DurationBehavior::CONSTANT));
   curve->SetInitialValue(initial_value);
   EXPECT_EQ(0.2, curve->Duration().InSecondsF());
+  EXPECT_EQ(1800.0, curve->GetValue(base::TimeDelta::FromSecondsD(0.1)).y());
+  EXPECT_EQ(3600.0, curve->GetValue(base::TimeDelta::FromSecondsD(0.2)).y());
 
   curve->UpdateTarget(0.1, gfx::ScrollOffset(0.0, 9900.0));
+
   EXPECT_EQ(0.3, curve->Duration().InSecondsF());
+  EXPECT_EQ(1800.0, curve->GetValue(base::TimeDelta::FromSecondsD(0.1)).y());
+  EXPECT_NEAR(6827.59, curve->GetValue(base::TimeDelta::FromSecondsD(0.2)).y(),
+              0.01);
+  EXPECT_EQ(9900.0, curve->GetValue(base::TimeDelta::FromSecondsD(0.3)).y());
+
+  curve->UpdateTarget(0.2, gfx::ScrollOffset(0.0, 7200.0));
+
+  // A closer target at high velocity reduces the duration.
+  EXPECT_NEAR(0.22, curve->Duration().InSecondsF(), 0.01);
+  EXPECT_NEAR(6827.59, curve->GetValue(base::TimeDelta::FromSecondsD(0.2)).y(),
+              0.01);
+  EXPECT_EQ(7200.0, curve->GetValue(base::TimeDelta::FromSecondsD(0.22)).y());
 }
 
 }  // namespace