simplify/unify xferproc api

gm/SkLinearBitmapPipelineGM.cpp

 /*
  * Copyright 2016 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"
 #include "SkBlitter.h"
 #include "SkCanvas.h"
@@ skipping 97 matching lines @@
     if (useBilerp) {
         filterQuality = SkFilterQuality::kLow_SkFilterQuality;
     } else {
         filterQuality = SkFilterQuality::kNone_SkFilterQuality;
     }
 
     uint32_t flags = 0;
     //if (kSRGB_SkColorProfileType == profile) {
         //flags |= SkXfermode::kDstIsSRGB_PM4fFlag;
     //}
-    const SkXfermode::PM4fState state { nullptr, flags };
-    auto procN = SkXfermode::GetPM4fProcN(SkXfermode::kSrcOver_Mode, flags);
+    auto procN = SkXfermode::GetD32Proc(nullptr, flags);
 
     SkLinearBitmapPipeline pipeline{
             inv, filterQuality,
             SkShader::kClamp_TileMode, SkShader::kClamp_TileMode, pmsrc};
 
     for (int y = 0; y < ir.height(); y++) {
         pipeline.shadeSpan4f(0, y, dstBits, ir.width());
-        procN(state, pmdst.writable_addr32(0, y), dstBits, ir.width(), nullptr);
+        procN(nullptr, pmdst.writable_addr32(0, y), dstBits, ir.width(), nullptr);
     }
 
     delete [] dstBits;
 
     canvas->drawBitmap(bmdst, r.left(), r.top(), nullptr);
 }
 
 static void draw_rect_none(SkCanvas* canvas, const SkRect& r, SkColor c) {
     const SkIRect ir = r.round();
 
@@ skipping 51 matching lines @@
             }
             canvas->restore();
             canvas->translate(0, H + 20);
         }
         canvas->restore();
         canvas->translate(0, (H + 20) * SK_ARRAY_COUNT(mats));
         if (useBilerp) break;
         useBilerp = true;
     }
 }