CC: Allow per-curve timing functions to be steps timing functions

cc/blink/web_transform_animation_curve_impl.cc

Index: cc/blink/web_transform_animation_curve_impl.cc
diff --git a/cc/blink/web_transform_animation_curve_impl.cc b/cc/blink/web_transform_animation_curve_impl.cc
index 80c1d1d02faaf9f7f0fae3ee0e10445b7e9c3c34..4dafd1012d49ce3e43e7a60ce6cf1767af4af2d0 100644
--- a/cc/blink/web_transform_animation_curve_impl.cc
+++ b/cc/blink/web_transform_animation_curve_impl.cc
@@ -64,19 +64,30 @@ void WebTransformAnimationCurveImpl::add(const WebTransformKeyframe& keyframe,
       cc::StepsTimingFunction::Create(steps, steps_start_offset)));
 }
 
-void WebTransformAnimationCurveImpl::setTimingFunction(
+void WebTransformAnimationCurveImpl::setLinearTimingFunction() {
+  curve_->SetTimingFunction(nullptr);
+}
+
+void WebTransformAnimationCurveImpl::setCubicBezierTimingFunction(
     TimingFunctionType type) {
   curve_->SetTimingFunction(CreateTimingFunction(type));
 }
 
-void WebTransformAnimationCurveImpl::setTimingFunction(double x1,
-                                                       double y1,
-                                                       double x2,
-                                                       double y2) {
+void WebTransformAnimationCurveImpl::setCubicBezierTimingFunction(double x1,
+                                                                  double y1,
+                                                                  double x2,
+                                                                  double y2) {
   curve_->SetTimingFunction(
       cc::CubicBezierTimingFunction::Create(x1, y1, x2, y2).Pass());
 }
 
+void WebTransformAnimationCurveImpl::setStepsTimingFunction(
+    int number_of_steps,
+    float steps_start_offset) {
+  curve_->SetTimingFunction(cc::StepsTimingFunction::Create(
+                                number_of_steps, steps_start_offset).Pass());
+}
+
 scoped_ptr<cc::AnimationCurve>
 WebTransformAnimationCurveImpl::CloneToAnimationCurve() const {
   return curve_->Clone();