Add XP to handle the cases where we disable color write.

src/gpu/effects/GrCoverageSetOpXP.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrCoverageSetOpXP_DEFINED
 #define GrCoverageSetOpXP_DEFINED
 
 #include "GrTypes.h"
 #include "GrXferProcessor.h"
 #include "SkRegion.h"
 
-class GrInvariantOutput;
 class GrProcOptInfo;
 
 /**
  * This xfer processor directly blends the the src coverage with the dst using a set operator. It is
  * useful for rendering coverage masks using CSG. It can optionally invert the src coverage before
  * applying the set operator.
  * */
 class GrCoverageSetOpXP : public GrXferProcessor {
 public:
     static GrXferProcessor* Create(SkRegion::Op regionOp, bool invertCoverage) {
         return SkNEW_ARGS(GrCoverageSetOpXP, (regionOp, invertCoverage));
     }
 
     ~GrCoverageSetOpXP() SK_OVERRIDE;
 
-    virtual const char* name() const SK_OVERRIDE { return "Coverage Set Op"; }
+    const char* name() const SK_OVERRIDE { return "Coverage Set Op"; }
 
     void getGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const SK_OVERRIDE;
 
     GrGLXferProcessor* createGLInstance() const SK_OVERRIDE;
 
     bool hasSecondaryOutput() const SK_OVERRIDE { return false; }
 
     GrXferProcessor::OptFlags getOptimizations(const GrProcOptInfo& colorPOI,
                                                const GrProcOptInfo& coveragePOI,
-                                               bool colorWriteDisabled,
                                                bool doesStencilWrite,
                                                GrColor* color,
                                                const GrDrawTargetCaps& caps) SK_OVERRIDE;
 
     void getBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const SK_OVERRIDE;
 
     bool invertCoverage() const { return fInvertCoverage; }
 
 private:
     GrCoverageSetOpXP(SkRegion::Op regionOp, bool fInvertCoverage);
@@ skipping 16 matching lines @@
 public:
     static GrXPFactory* Create(SkRegion::Op regionOp, bool invertCoverage = false);
 
     GrXferProcessor* createXferProcessor(const GrProcOptInfo& colorPOI,
                                          const GrProcOptInfo& coveragePOI) const SK_OVERRIDE;
 
     bool supportsRGBCoverage(GrColor knownColor, uint32_t knownColorFlags) const SK_OVERRIDE {
         return true;
     }
 
-    bool canApplyCoverage(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
-                          bool colorWriteDisabled) const SK_OVERRIDE {
+    bool canApplyCoverage(const GrProcOptInfo& colorPOI,
+                          const GrProcOptInfo& coveragePOI) const SK_OVERRIDE {
         return true;
     }
 
     bool canTweakAlphaForCoverage() const SK_OVERRIDE { return false; }
 
     void getInvariantOutput(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
-                            bool colorWriteDisabled,
                             GrXPFactory::InvariantOutput*) const SK_OVERRIDE;
 
+    bool willReadDst(const GrProcOptInfo& colorPOI,
+                     const GrProcOptInfo& coveragePOI) const SK_OVERRIDE;
+
 private:
     GrCoverageSetOpXPFactory(SkRegion::Op regionOp, bool invertCoverage);
 
     bool onIsEqual(const GrXPFactory& xpfBase) const SK_OVERRIDE {
         const GrCoverageSetOpXPFactory& xpf = xpfBase.cast<GrCoverageSetOpXPFactory>();
         return fRegionOp == xpf.fRegionOp;
     }
 
     GR_DECLARE_XP_FACTORY_TEST;
 
     SkRegion::Op fRegionOp;
     bool         fInvertCoverage;
 
     typedef GrXPFactory INHERITED;
 };
 #endif