cc: Change scoped_ptr<T>() to nullptr.

cc/layers/layer_unittest.cc

Index: cc/layers/layer_unittest.cc
diff --git a/cc/layers/layer_unittest.cc b/cc/layers/layer_unittest.cc
index a3ef621bb7056b69246181fe96075f4f0b53819e..e32a6e7eb3e1a625c288262ca7fc68dc26e8f36a 100644
--- a/cc/layers/layer_unittest.cc
+++ b/cc/layers/layer_unittest.cc
@@ -1141,12 +1141,8 @@ TEST(LayerLayerTreeHostTest, DestroyHostWithNonNullRootLayer) {
 static bool AddTestAnimation(Layer* layer) {
   scoped_ptr<KeyframedFloatAnimationCurve> curve =
       KeyframedFloatAnimationCurve::Create();
-  curve->AddKeyframe(FloatKeyframe::Create(0.0,
-                                           0.3f,
-                                           scoped_ptr<TimingFunction>()));
-  curve->AddKeyframe(FloatKeyframe::Create(1.0,
-                                           0.7f,
-                                           scoped_ptr<TimingFunction>()));
+  curve->AddKeyframe(FloatKeyframe::Create(0.0, 0.3f, nullptr));
+  curve->AddKeyframe(FloatKeyframe::Create(1.0, 0.7f, nullptr));
   scoped_ptr<Animation> animation =
       Animation::Create(curve.Pass(), 0, 0, Animation::Opacity);