Don't create a GXPFactory when blend is SrcOver

gm/rrects.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 #if SK_SUPPORT_GPU
 #include "GrTest.h"
@@ skipping 89 matching lines @@
                     canvas->translate(SkIntToScalar(x), SkIntToScalar(y));
                     if (kEffect_Type == fType) {
 #if SK_SUPPORT_GPU
                         GrTestTarget tt;
                         context->getTestTarget(&tt, rt);
                         if (nullptr == tt.target()) {
                             SkDEBUGFAIL("Couldn't get Gr test target.");
                             return;
                         }
                         GrPipelineBuilder pipelineBuilder;
+                        pipelineBuilder.setXPFactory(
+                            GrPorterDuffXPFactory::Create(SkXfermode::kSrc_Mode))->unref();
 
                         SkRRect rrect = fRRects[curRRect];
                         rrect.offset(SkIntToScalar(x), SkIntToScalar(y));
                         GrPrimitiveEdgeType edgeType = (GrPrimitiveEdgeType) et;
                         SkAutoTUnref<GrFragmentProcessor> fp(GrRRectEffect::Create(edgeType,
                                                                                    rrect));
                         if (fp) {
                             pipelineBuilder.addCoverageFragmentProcessor(fp);
                             pipelineBuilder.setRenderTarget(rt);
 
@@ skipping 137 matching lines @@
 
 DEF_GM( return new RRectGM(RRectGM::kAA_Draw_Type); )
 DEF_GM( return new RRectGM(RRectGM::kBW_Draw_Type); )
 DEF_GM( return new RRectGM(RRectGM::kAA_Clip_Type); )
 DEF_GM( return new RRectGM(RRectGM::kBW_Clip_Type); )
 #if SK_SUPPORT_GPU
 DEF_GM( return new RRectGM(RRectGM::kEffect_Type); )
 #endif
 
 }