move experimental header out of public includes

Bug: skia:
Change-Id: I81ea9e039f23e22b4955ad6088f5cb76ec2ba1a5
Reviewed-on: https://skia-review.googlesource.com/c/186864
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Mike Reed <reed@google.com>

gn/core.gni

@@ -148,7 +148,6 @@ skia_core_sources = [
   "$_src/core/SkImageFilterCache.h",
   "$_src/core/SkImageInfo.cpp",
   "$_src/core/SkImageGenerator.cpp",
-  "$_src/core/SkLights.cpp",
   "$_src/core/SkLineClipper.cpp",
   "$_src/core/SkLiteDL.cpp",
   "$_src/core/SkLiteRecorder.cpp",
@@ -343,6 +342,8 @@ skia_core_sources = [
   "$_src/shaders/SkImageShader.h",
   "$_src/shaders/SkLightingShader.cpp",
   "$_src/shaders/SkLightingShader.h",
+  "$_src/shaders/SkLights.cpp",
+  "$_src/shaders/SkLights.h",
   "$_src/shaders/SkLocalMatrixShader.cpp",
   "$_src/shaders/SkLocalMatrixShader.h",
   "$_src/shaders/SkShader.cpp",
@@ -373,7 +374,6 @@ skia_core_sources = [
   "$_include/core/SkImageFilter.h",
   "$_include/core/SkImageGenerator.h",
   "$_include/core/SkImageInfo.h",
-  "$_include/core/SkLights.h",
   "$_include/core/SkMallocPixelRef.h",
   "$_include/core/SkMaskFilter.h",
   "$_include/core/SkMath.h",

src/shaders/SkLightingShader.h

@@ -15,7 +15,7 @@ class SkBitmap;
 class SkMatrix;
 class SkNormalSource;
 
-class SK_API SkLightingShader {
+class SkLightingShader {
 public:
     /** Returns a shader that lights the shape, colored by the diffuseShader, using the
         normals from normalSource, with the set of lights provided.