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

src/gpu/effects/GrCustomXfermode.cpp

Index: src/gpu/effects/GrCustomXfermode.cpp
diff --git a/src/gpu/effects/GrCustomXfermode.cpp b/src/gpu/effects/GrCustomXfermode.cpp
index 9aa71531096c0db3418626ba2c5e4c1d0890aab2..b77bf2fad174771a22f24ae2c00db09a50fed260 100644
--- a/src/gpu/effects/GrCustomXfermode.cpp
+++ b/src/gpu/effects/GrCustomXfermode.cpp
@@ -499,20 +499,6 @@
     GLCustomXP(const GrXferProcessor&) {}
     ~GLCustomXP() SK_OVERRIDE {}
 
-    void emitCode(const EmitArgs& args) SK_OVERRIDE {
-        SkXfermode::Mode mode = args.fXP.cast<GrCustomXP>().mode();
-        GrGLFPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();
-        const char* dstColor = fsBuilder->dstColor();
-
-        emit_custom_xfermode_code(mode, fsBuilder, args.fOutputPrimary, args.fInputColor, dstColor);
-
-        fsBuilder->codeAppendf("%s = %s * %s + (vec4(1.0) - %s) * %s;",
-                               args.fOutputPrimary, args.fOutputPrimary, args.fInputCoverage,
-                               args.fInputCoverage, dstColor);
-    }
-
-    void setData(const GrGLProgramDataManager&, const GrXferProcessor&) SK_OVERRIDE {}
-
     static void GenKey(const GrXferProcessor& proc, const GrGLCaps&, GrProcessorKeyBuilder* b) {
         uint32_t key = proc.numTextures();
         SkASSERT(key <= 1);
@@ -521,18 +507,32 @@
     }
 
 private:
+    void onEmitCode(const EmitArgs& args) SK_OVERRIDE {
+        SkXfermode::Mode mode = args.fXP.cast<GrCustomXP>().mode();
+        GrGLFPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();
+        const char* dstColor = fsBuilder->dstColor();
+
+        emit_custom_xfermode_code(mode, fsBuilder, args.fOutputPrimary, args.fInputColor, dstColor);
+
+        fsBuilder->codeAppendf("%s = %s * %s + (vec4(1.0) - %s) * %s;",
+                               args.fOutputPrimary, args.fOutputPrimary, args.fInputCoverage,
+                               args.fInputCoverage, dstColor);
+    }
+
+    void onSetData(const GrGLProgramDataManager&, const GrXferProcessor&) SK_OVERRIDE {}
+
     typedef GrGLFragmentProcessor INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
-GrCustomXP::GrCustomXP(SkXfermode::Mode mode)
-    : fMode(mode) {
+GrCustomXP::GrCustomXP(SkXfermode::Mode mode, const GrDeviceCoordTexture* dstCopy,
+                       bool willReadDstColor)
+    : INHERITED(dstCopy, willReadDstColor), fMode(mode) {
     this->initClassID<GrCustomXP>();
-    this->setWillReadDstColor();
-}
-
-void GrCustomXP::getGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const {
+}
+
+void GrCustomXP::onGetGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const {
     GLCustomXP::GenKey(*this, caps, b);
 }