Revert[8] "replace SkXfermode obj with SkBlendMode enum in paints"

tests/ApplyGammaTest.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 <initializer_list>
 #include "Test.h"
 
@@ skipping 94 matching lines @@
                 ERRORF(reporter, "Could not create surfaces for copy surface test.");
                 continue;
             }
 
             SkCanvas* dstCanvas = dst->getCanvas();
 
             dstCanvas->clear(SK_ColorRED);
             dstCanvas->flush();
 
             SkPaint gammaPaint;
-            gammaPaint.setXfermodeMode(SkXfermode::kSrc_Mode);
+            gammaPaint.setBlendMode(SkBlendMode::kSrc);
             gammaPaint.setColorFilter(SkGammaColorFilter::Make(gamma));
 
             dstCanvas->drawImage(src, 0, 0, &gammaPaint);
             dstCanvas->flush();
 
             sk_memset32(read.get(), 0, kW * kH);
             if (!dstCanvas->readPixels(ii, read.get(), kRowBytes, 0, 0)) {
                 ERRORF(reporter, "Error calling readPixels");
                 continue;
             }
@@ skipping 11 matching lines @@
                                 x, y, expected, s, gamma, r);
                         abort = true;
                         break;
                     }
                 }
             }
         }
     }
 }
 #endif