Add an InvariantOutput for the XPF.

src/gpu/effects/GrCoverageSetOpXP.h

Index: src/gpu/effects/GrCoverageSetOpXP.h
diff --git a/src/gpu/effects/GrCoverageSetOpXP.h b/src/gpu/effects/GrCoverageSetOpXP.h
index 327d3c01f0f249edc106c92d5f4cbc6ed4167ba6..e3ce07ca75b710931b84ec2721379e02366fc285 100644
--- a/src/gpu/effects/GrCoverageSetOpXP.h
+++ b/src/gpu/effects/GrCoverageSetOpXP.h
@@ -80,15 +80,11 @@ public:
         return true;
     }
 
-    bool willBlendWithDst(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
-                          bool colorWriteDisabled) const SK_OVERRIDE;
-
     bool canTweakAlphaForCoverage() const SK_OVERRIDE { return false; }
 
-    bool getOpaqueAndKnownColor(const GrProcOptInfo& colorPOI,
-                                const GrProcOptInfo& coveragePOI,
-                                GrColor* solidColor,
-                                uint32_t* solidColorKnownComponents) const SK_OVERRIDE;
+    void getInvariantOutput(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
+                            bool colorWriteDisabled,
+                            GrXPFactory::InvariantOutput*) const SK_OVERRIDE;
 
 private:
     GrCoverageSetOpXPFactory(SkRegion::Op regionOp, bool invertCoverage);