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

src/core/SkBlitter_ARGB32.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCoreBlitters.h"
 #include "SkColorPriv.h"
 #include "SkShader.h"
@@ skipping 321 matching lines @@
         device[i] = SkFourByteInterp256(span[i], device[i], aa256);
     }
 }
 
 SkARGB32_Shader_Blitter::SkARGB32_Shader_Blitter(const SkPixmap& device,
         const SkPaint& paint, SkShader::Context* shaderContext)
     : INHERITED(device, paint, shaderContext)
 {
     fBuffer = (SkPMColor*)sk_malloc_throw(device.width() * (sizeof(SkPMColor)));
 
-    fXfermode = paint.getXfermode();
-    SkSafeRef(fXfermode);
+    fXfermode = SkXfermode::Peek(paint.getBlendMode());
 
     int flags = 0;
     if (!(shaderContext->getFlags() & SkShader::kOpaqueAlpha_Flag)) {
         flags |= SkBlitRow::kSrcPixelAlpha_Flag32;
     }
     // we call this on the output from the shader
     fProc32 = SkBlitRow::Factory32(flags);
     // we call this on the output from the shader + alpha from the aa buffer
     fProc32Blend = SkBlitRow::Factory32(flags | SkBlitRow::kGlobalAlpha_Flag32);
 
     fShadeDirectlyIntoDevice = false;
     if (fXfermode == nullptr) {
         if (shaderContext->getFlags() & SkShader::kOpaqueAlpha_Flag) {
             fShadeDirectlyIntoDevice = true;
         }
     } else {
         SkXfermode::Mode mode;
         if (fXfermode->asMode(&mode)) {
             if (SkXfermode::kSrc_Mode == mode) {
                 fShadeDirectlyIntoDevice = true;
                 fProc32Blend = blend_srcmode;
             }
         }
     }
 
     fConstInY = SkToBool(shaderContext->getFlags() & SkShader::kConstInY32_Flag);
 }
 
 SkARGB32_Shader_Blitter::~SkARGB32_Shader_Blitter() {
-    SkSafeUnref(fXfermode);
     sk_free(fBuffer);
 }
 
 void SkARGB32_Shader_Blitter::blitH(int x, int y, int width) {
     SkASSERT(x >= 0 && y >= 0 && x + width <= fDevice.width());
 
     uint32_t* device = fDevice.writable_addr32(x, y);
 
     if (fShadeDirectlyIntoDevice) {
         fShaderContext->shadeSpan(x, y, device, width);
@@ skipping 306 matching lines @@
             SkBlitRow::Proc32 proc = (255 == alpha) ? fProc32 : fProc32Blend;
             do {
                 shaderContext->shadeSpan(x, y, span, 1);
                 proc(device, span, 1, alpha);
                 y += 1;
                 device = (uint32_t*)((char*)device + deviceRB);
             } while (--height > 0);
         }
     }
 }