[Reland] Relocate shaders to own dir

Consolidate all shader impls under src/shaders/.

(reland of https://skia-review.googlesource.com/c/17927/)

Change-Id: I7918bdc1aafe842ed194412ba95b9ae53a2ec1d7
Reviewed-on: https://skia-review.googlesource.com/18146
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
diff --git a/gn/effects.gni b/gn/effects.gni
index 8758212..61b1b39 100644
--- a/gn/effects.gni
+++ b/gn/effects.gni
@@ -54,7 +54,6 @@
   "$_src/effects/SkPackBits.h",
   "$_src/effects/SkPaintFlagsDrawFilter.cpp",
   "$_src/effects/SkPaintImageFilter.cpp",
-  "$_src/effects/SkPerlinNoiseShader.cpp",
   "$_src/effects/SkPictureImageFilter.cpp",
   "$_src/effects/SkRRectsGaussianEdgeMaskFilter.cpp",
   "$_src/effects/SkTableColorFilter.cpp",
@@ -62,27 +61,28 @@
   "$_src/effects/SkTileImageFilter.cpp",
   "$_src/effects/SkXfermodeImageFilter.cpp",
 
-  "$_src/effects/gradients/Sk4fGradientBase.cpp",
-  "$_src/effects/gradients/Sk4fGradientBase.h",
-  "$_src/effects/gradients/Sk4fGradientPriv.h",
-  "$_src/effects/gradients/Sk4fLinearGradient.cpp",
-  "$_src/effects/gradients/Sk4fLinearGradient.h",
-  "$_src/effects/gradients/SkClampRange.cpp",
-  "$_src/effects/gradients/SkClampRange.h",
-  "$_src/effects/gradients/SkGradientBitmapCache.cpp",
-  "$_src/effects/gradients/SkGradientBitmapCache.h",
-  "$_src/effects/gradients/SkGradientShader.cpp",
-  "$_src/effects/gradients/SkGradientShaderPriv.h",
-  "$_src/effects/gradients/SkLinearGradient.cpp",
-  "$_src/effects/gradients/SkLinearGradient.h",
-  "$_src/effects/gradients/SkRadialGradient.cpp",
-  "$_src/effects/gradients/SkRadialGradient.h",
-  "$_src/effects/gradients/SkTwoPointConicalGradient.cpp",
-  "$_src/effects/gradients/SkTwoPointConicalGradient.h",
-  "$_src/effects/gradients/SkTwoPointConicalGradient_gpu.cpp",
-  "$_src/effects/gradients/SkTwoPointConicalGradient_gpu.h",
-  "$_src/effects/gradients/SkSweepGradient.cpp",
-  "$_src/effects/gradients/SkSweepGradient.h",
+  "$_src/shaders/SkPerlinNoiseShader.cpp",
+  "$_src/shaders/gradients/Sk4fGradientBase.cpp",
+  "$_src/shaders/gradients/Sk4fGradientBase.h",
+  "$_src/shaders/gradients/Sk4fGradientPriv.h",
+  "$_src/shaders/gradients/Sk4fLinearGradient.cpp",
+  "$_src/shaders/gradients/Sk4fLinearGradient.h",
+  "$_src/shaders/gradients/SkClampRange.cpp",
+  "$_src/shaders/gradients/SkClampRange.h",
+  "$_src/shaders/gradients/SkGradientBitmapCache.cpp",
+  "$_src/shaders/gradients/SkGradientBitmapCache.h",
+  "$_src/shaders/gradients/SkGradientShader.cpp",
+  "$_src/shaders/gradients/SkGradientShaderPriv.h",
+  "$_src/shaders/gradients/SkLinearGradient.cpp",
+  "$_src/shaders/gradients/SkLinearGradient.h",
+  "$_src/shaders/gradients/SkRadialGradient.cpp",
+  "$_src/shaders/gradients/SkRadialGradient.h",
+  "$_src/shaders/gradients/SkTwoPointConicalGradient.cpp",
+  "$_src/shaders/gradients/SkTwoPointConicalGradient.h",
+  "$_src/shaders/gradients/SkTwoPointConicalGradient_gpu.cpp",
+  "$_src/shaders/gradients/SkTwoPointConicalGradient_gpu.h",
+  "$_src/shaders/gradients/SkSweepGradient.cpp",
+  "$_src/shaders/gradients/SkSweepGradient.h",
 
   "$_include/effects/Sk1DPathEffect.h",
   "$_include/effects/Sk2DPathEffect.h",