move blur impl into core

Ever since we added drawShadow to the public api, blurs have necessarily
part of the core. This CL just formalizes that.

This should also allow us to have builds that exclude all of /effects (for code size)
and still be valid.

Will follow-up with a change to deprecate SkBlurMaskFilter and SkBlurQuality (both no longer needed).

Bug: skia:
Change-Id: Ifbbd8b47a30a0386d215726b67bcf1e8b84fb8f5
Reviewed-on: https://skia-review.googlesource.com/113713
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/gn/sksl.gni b/gn/sksl.gni
index 6248e69..974ac16 100644
--- a/gn/sksl.gni
+++ b/gn/sksl.gni
@@ -27,10 +27,10 @@
 
 skia_gpu_processor_sources = [
   "$_src/effects/GrAlphaThresholdFragmentProcessor.fp",
-  "$_src/effects/GrCircleBlurFragmentProcessor.fp",
   "$_src/gpu/effects/GrAARectEffect.fp",
   "$_src/gpu/effects/GrArithmeticFP.fp",
   "$_src/gpu/effects/GrBlurredEdgeFragmentProcessor.fp",
+  "$_src/gpu/effects/GrCircleBlurFragmentProcessor.fp",
   "$_src/gpu/effects/GrCircleEffect.fp",
   "$_src/gpu/effects/GrConfigConversionEffect.fp",
   "$_src/gpu/effects/GrConstColorProcessor.fp",