Add an InvariantOutput for the XPF.

src/gpu/GrDrawState.cpp

Index: src/gpu/GrDrawState.cpp
diff --git a/src/gpu/GrDrawState.cpp b/src/gpu/GrDrawState.cpp
index 711fdcb23a8902c4d88c3d0e4dcea94b58870bf1..883c74b8ee65ef6b15dddf06143f23afa5529cf5 100644
--- a/src/gpu/GrDrawState.cpp
+++ b/src/gpu/GrDrawState.cpp
@@ -339,8 +339,11 @@ GrDrawState::~GrDrawState() {
 bool GrDrawState::willBlendWithDst(const GrPrimitiveProcessor* pp) const {
     this->calcColorInvariantOutput(pp);
     this->calcCoverageInvariantOutput(pp);
-    return fXPFactory->willBlendWithDst(fColorProcInfo, fCoverageProcInfo,
-                                        this->isColorWriteDisabled());
+    
+    GrXPFactory::InvariantOutput output;
+    fXPFactory->getInvariantOutput(fColorProcInfo, fCoverageProcInfo, this->isColorWriteDisabled(),
+                                   &output);
+    return output.fWillBlendWithDst;
 }
 
 void GrDrawState::calcColorInvariantOutput(const GrPrimitiveProcessor* pp) const {