Define accelerated steps time function.

webkit/renderer/compositor_bindings/web_transform_animation_curve_impl.cc

Index: webkit/renderer/compositor_bindings/web_transform_animation_curve_impl.cc
diff --git a/webkit/renderer/compositor_bindings/web_transform_animation_curve_impl.cc b/webkit/renderer/compositor_bindings/web_transform_animation_curve_impl.cc
index 1b0d073b21eede8b80c8f72834dcfee93cb06483..34211cb37f6bae6b0843d8a26b3e73a58dde73f0 100644
--- a/webkit/renderer/compositor_bindings/web_transform_animation_curve_impl.cc
+++ b/webkit/renderer/compositor_bindings/web_transform_animation_curve_impl.cc
@@ -29,6 +29,19 @@ void WebTransformAnimationCurveImpl::add(const WebTransformKeyframe& keyframe) {
 }
 
 void WebTransformAnimationCurveImpl::add(const WebTransformKeyframe& keyframe,
+                                         int steps,
+                                         bool stepsAtStart) {
+  const cc::TransformOperations& transform_operations =
+      static_cast<const webkit::WebTransformOperationsImpl&>(keyframe.value())
+      .AsTransformOperations();
+      curve_->AddKeyframe(cc::TransformKeyframe::Create(
+          keyframe.time(),
+          transform_operations,
+          cc::StepsTimingFunction::Create(steps, stepsAtStart)
+            .PassAs<cc::TimingFunction>()));
+}
+
+void WebTransformAnimationCurveImpl::add(const WebTransformKeyframe& keyframe,
                                          TimingFunctionType type) {
   const cc::TransformOperations& transform_operations =
       static_cast<const webkit::WebTransformOperationsImpl&>(keyframe.value())