Add shader based blending of kPlus for configs that need clamping

This effectively reverts https://skia-review.googlesource.com/c/skia/+/140500
and relands https://skia-review.googlesource.com/c/skia/+/48183.

Bug: skia:8871
Change-Id: I6b1d5daa3d319e0c078e553926ed9166cca9a24a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/199930
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/ops/GrRegionOp.cpp b/src/gpu/ops/GrRegionOp.cpp
index 91ec455..3b1c39a 100644
--- a/src/gpu/ops/GrRegionOp.cpp
+++ b/src/gpu/ops/GrRegionOp.cpp
@@ -88,10 +88,10 @@
 
     FixedFunctionFlags fixedFunctionFlags() const override { return fHelper.fixedFunctionFlags(); }
 
-    GrProcessorSet::Analysis finalize(
-            const GrCaps& caps, const GrAppliedClip* clip, GrFSAAType fsaaType) override {
-        return fHelper.finalizeProcessors(
-                caps, clip, fsaaType, GrProcessorAnalysisCoverage::kNone, &fRegions[0].fColor);
+    GrProcessorSet::Analysis finalize(const GrCaps& caps, const GrAppliedClip* clip,
+                                      GrFSAAType fsaaType, GrClampType clampType) override {
+        return fHelper.finalizeProcessors(caps, clip, fsaaType, clampType,
+                                          GrProcessorAnalysisCoverage::kNone, &fRegions[0].fColor);
     }
 
 private: