Add XferProcessor factory in GrPaint and GrDrawState.

src/gpu/GrOptDrawState.cpp

Index: src/gpu/GrOptDrawState.cpp
diff --git a/src/gpu/GrOptDrawState.cpp b/src/gpu/GrOptDrawState.cpp
index 41a34c4ed2d885bedb7653d1152704e4cf3dd8bf..6f6f0af88821741649829ad680d488e15bdac12a 100644
--- a/src/gpu/GrOptDrawState.cpp
+++ b/src/gpu/GrOptDrawState.cpp
@@ -100,6 +100,11 @@ GrOptDrawState::GrOptDrawState(const GrDrawState& drawState,
              drawState.hasGeometryProcessor());
     fGeometryProcessor.reset(drawState.getGeometryProcessor());
 
+    // Create XferProcessor from DS's XPFactory
+    const GrXferProcessor* xpProcessor = drawState.getXPFactory()->createXferProcessor();
+    fXferProcessor.reset(xpProcessor);
+    xpProcessor->unref();
+
     // Copy Stages from DS to ODS
     for (int i = firstColorStageIdx; i < drawState.numColorStages(); ++i) {
         SkNEW_APPEND_TO_TARRAY(&fFragmentStages,