added support for PLS path rendering

src/gpu/GrXferProcessor.cpp

Index: src/gpu/GrXferProcessor.cpp
diff --git a/src/gpu/GrXferProcessor.cpp b/src/gpu/GrXferProcessor.cpp
index b07b9720df69e6677fad14b27286bab90fc419b3..8f47254af8cbd758b6ef96b344b741374944f0a5 100644
--- a/src/gpu/GrXferProcessor.cpp
+++ b/src/gpu/GrXferProcessor.cpp
@@ -217,3 +217,9 @@ bool GrXPFactory::willNeedDstTexture(const GrCaps& caps,
     return (this->willReadDstColor(caps, optimizations, hasMixedSamples) &&
             !caps.shaderCaps()->dstReadInShaderSupport());
 }
+
+bool GrXPFactory::willReadDstColor(const GrCaps& caps,
+                                   const GrPipelineOptimizations& optimizations,
+                                   bool hasMixedSamples) const {
+        return optimizations.fOverrides.fUsePLSDstRead;
+}