Add XferProcessor factory in GrPaint and GrDrawState.

src/gpu/GrPaint.cpp

Index: src/gpu/GrPaint.cpp
diff --git a/src/gpu/GrPaint.cpp b/src/gpu/GrPaint.cpp
index 7d89535a11c7be1d1b2ace710c0b650af2f9a555..bd5b2860f474e158e200827a9182a27a54632312 100644
--- a/src/gpu/GrPaint.cpp
+++ b/src/gpu/GrPaint.cpp
@@ -10,6 +10,7 @@
 
 #include "GrBlend.h"
 #include "GrProcOptInfo.h"
+#include "effects/GrPorterDuffXferProcessor.h"
 #include "effects/GrSimpleTextureEffect.h"
 
 void GrPaint::addColorTextureProcessor(GrTexture* texture, const SkMatrix& matrix) {
@@ -48,6 +49,13 @@ bool GrPaint::isOpaqueAndConstantColor(GrColor* color) const {
     return false;
 }
 
+void GrPaint::resetStages() {
+    fColorStages.reset();
+    fCoverageStages.reset();
+    fXPFactory.reset(GrPorterDuffXPFactory::Create(kOne_GrBlendCoeff,
+                                                   kZero_GrBlendCoeff));
+}
+
 bool GrPaint::getOpaqueAndKnownColor(GrColor* solidColor,
                                      uint32_t* solidColorKnownComponents) const {
 
@@ -114,3 +122,4 @@ bool GrPaint::getOpaqueAndKnownColor(GrColor* solidColor,
     }
     return opaque;
 }
+