Use SkXfermode as public facing enum for GrPorterDuffXP

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 GrProcOptInfo;
-
-class GrCoverageSetOpXPFactory : public GrXPFactory {
-public:
-    static GrXPFactory* Create(SkRegion::Op regionOp, bool invertCoverage = false);
-
-    bool supportsRGBCoverage(GrColor knownColor, uint32_t knownColorFlags) const SK_OVERRIDE {
-        return true;
-    }
-
-    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,
-                            GrXPFactory::InvariantOutput*) const SK_OVERRIDE;
-
-private:
-    GrCoverageSetOpXPFactory(SkRegion::Op regionOp, bool invertCoverage);
-
-    GrXferProcessor* onCreateXferProcessor(const GrProcOptInfo& colorPOI,
-                                           const GrProcOptInfo& coveragePOI,
-                                           const GrDeviceCoordTexture* dstCopy) const SK_OVERRIDE;
-
-    bool willReadDstColor(const GrProcOptInfo& colorPOI,
-                          const GrProcOptInfo& coveragePOI) const SK_OVERRIDE {
-        return false;
-    }
-
-    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
-