Revert of Revert of Move DstCopy on gpu into the GrXferProcessor.

src/gpu/effects/GrCustomXfermodePriv.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrCustomXfermodePriv_DEFINED
 #define GrCustomXfermodePriv_DEFINED
 
 #include "GrCoordTransform.h"
+#include "GrDrawTargetCaps.h"
 #include "GrFragmentProcessor.h"
 #include "GrTextureAccess.h"
 #include "GrXferProcessor.h"
 #include "SkXfermode.h"
 
 class GrGLCaps;
 class GrGLFragmentProcessor;
 class GrInvariantOutput;
 class GrProcessorKeyBuilder;
 class GrTexture;
@@ skipping 28 matching lines @@
 
     typedef GrFragmentProcessor INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 // Xfer Processor
 ///////////////////////////////////////////////////////////////////////////////
 
 class GrCustomXP : public GrXferProcessor {
 public:
-    static GrXferProcessor* Create(SkXfermode::Mode mode) {
+    static GrXferProcessor* Create(SkXfermode::Mode mode, const GrDeviceCoordTexture* dstCopy,
+                                   bool willReadDstColor) {
         if (!GrCustomXfermode::IsSupportedMode(mode)) {
             return NULL;
         } else {
-            return SkNEW_ARGS(GrCustomXP, (mode));
+            return SkNEW_ARGS(GrCustomXP, (mode, dstCopy, willReadDstColor));
         }
     }
 
     ~GrCustomXP() SK_OVERRIDE {};
 
     const char* name() const SK_OVERRIDE { return "Custom Xfermode"; }
 
-    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 doesStencilWrite,
                                                GrColor* overrideColor,
                                                const GrDrawTargetCaps& caps) SK_OVERRIDE;
 
     void getBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const SK_OVERRIDE {
         blendInfo->fSrcBlend = kOne_GrBlendCoeff;
         blendInfo->fDstBlend = kZero_GrBlendCoeff;
         blendInfo->fBlendConstant = 0;
     }
 
     SkXfermode::Mode mode() const { return fMode; }
 
 private:
-    GrCustomXP(SkXfermode::Mode mode);
+    GrCustomXP(SkXfermode::Mode mode, const GrDeviceCoordTexture* dstCopy, bool willReadDstColor);
+
+    void onGetGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const SK_OVERRIDE;
 
     bool onIsEqual(const GrXferProcessor& xpBase) const SK_OVERRIDE;
 
     SkXfermode::Mode fMode;
 
     typedef GrXferProcessor INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 class GrCustomXPFactory : public GrXPFactory {
 public:
     GrCustomXPFactory(SkXfermode::Mode mode); 
 
-    GrXferProcessor* createXferProcessor(const GrProcOptInfo& colorPOI,
-                                         const GrProcOptInfo& coveragePOI) const SK_OVERRIDE {
-        return GrCustomXP::Create(fMode);
-    }
-
     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;
 
-    bool willReadDst() const SK_OVERRIDE { return true; }
+private:
+    GrXferProcessor* onCreateXferProcessor(const GrProcOptInfo& colorPOI,
+                                           const GrProcOptInfo& coveragePOI,
+                                           const GrDeviceCoordTexture* dstCopy) const SK_OVERRIDE {
+        return GrCustomXP::Create(fMode, dstCopy, this->willReadDstColor());
+    }
 
-private:
+    bool willReadDstColor() const SK_OVERRIDE { return true; }
+
     bool onIsEqual(const GrXPFactory& xpfBase) const SK_OVERRIDE {
         const GrCustomXPFactory& xpf = xpfBase.cast<GrCustomXPFactory>();
         return fMode == xpf.fMode;
     }
 
     GR_DECLARE_XP_FACTORY_TEST;
 
     SkXfermode::Mode fMode;
 
     typedef GrXPFactory INHERITED;
 };
 #endif