Added PointLights to SkLights::Light

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2237493002

Review-Url: https://codereview.chromium.org/2237493002
diff --git a/samplecode/SampleLighting.cpp b/samplecode/SampleLighting.cpp
index 1c86c99..bab2b5d 100755
--- a/samplecode/SampleLighting.cpp
+++ b/samplecode/SampleLighting.cpp
@@ -21,8 +21,8 @@
 
     SkLights::Builder builder;
 
-    builder.add(SkLights::Light(SkColor3f::Make(1.0f, 1.0f, blue), dir));
-    builder.add(SkLights::Light(SkColor3f::Make(0.1f, 0.1f, 0.1f)));
+    builder.add(SkLights::Light::MakeDirectional(SkColor3f::Make(1.0f, 1.0f, blue), dir));
+    builder.add(SkLights::Light::MakeAmbient(SkColor3f::Make(0.1f, 0.1f, 0.1f)));
 
     return builder.finish();
 }