added support for PLS path rendering

src/gpu/effects/GrCustomXfermode.cpp

Index: src/gpu/effects/GrCustomXfermode.cpp
diff --git a/src/gpu/effects/GrCustomXfermode.cpp b/src/gpu/effects/GrCustomXfermode.cpp
index 04ff4a746ba733692ddab05ebb012f94ee341afb..dc4e7a4d7c6332cb306706d4ca129e2d6e416b67 100644
--- a/src/gpu/effects/GrCustomXfermode.cpp
+++ b/src/gpu/effects/GrCustomXfermode.cpp
@@ -54,12 +54,15 @@ static GrBlendEquation hw_blend_equation(SkXfermode::Mode mode) {
 }
 
 static bool can_use_hw_blend_equation(GrBlendEquation equation,
-                                      const GrProcOptInfo& coveragePOI,
+                                      const GrPipelineOptimizations& opt,
                                       const GrCaps& caps) {
     if (!caps.advancedBlendEquationSupport()) {
         return false;
     }
-    if (coveragePOI.isFourChannelOutput()) {
+    if (opt.fOverrides.fUsePLSDstRead) {
+        return false;
+    }
+    if (opt.fCoveragePOI.isFourChannelOutput()) {
         return false; // LCD coverage must be applied after the blend equation.
     }
     if (caps.canUseAdvancedBlendEquation(equation)) {
@@ -371,7 +374,7 @@ GrXferProcessor* CustomXPFactory::onCreateXferProcessor(const GrCaps& caps,
                                                         const GrPipelineOptimizations& opt,
                                                         bool hasMixedSamples,
                                                         const DstTexture* dstTexture) const {
-    if (can_use_hw_blend_equation(fHWBlendEquation, opt.fCoveragePOI, caps)) {
+    if (can_use_hw_blend_equation(fHWBlendEquation, opt, caps)) {
         SkASSERT(!dstTexture || !dstTexture->texture());
         return new CustomXP(fMode, fHWBlendEquation);
     }
@@ -381,7 +384,7 @@ GrXferProcessor* CustomXPFactory::onCreateXferProcessor(const GrCaps& caps,
 bool CustomXPFactory::willReadDstColor(const GrCaps& caps,
                                        const GrPipelineOptimizations& optimizations,
                                        bool hasMixedSamples) const {
-    return !can_use_hw_blend_equation(fHWBlendEquation, optimizations.fCoveragePOI, caps);
+    return !can_use_hw_blend_equation(fHWBlendEquation, optimizations, caps);
 }
 
 void CustomXPFactory::getInvariantBlendedColor(const GrProcOptInfo& colorPOI,