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

src/core/SkBlitter_PM4f.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 "SkCoreBlitters.h"
 #include "SkColorPriv.h"
 #include "SkShader.h"
@@ skipping 307 matching lines @@
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 static bool is_opaque(const SkPaint& paint, const SkShader::Context* shaderContext) {
     return shaderContext ? SkToBool(shaderContext->getFlags() & SkShader::kOpaqueAlpha_Flag)
     : 0xFF == paint.getAlpha();
 }
 
 struct State4f {
     State4f(const SkImageInfo& info, const SkPaint& paint, const SkShader::Context* shaderContext) {
-        fXfer = paint.getXfermode();
+        fXfer = SkXfermode::Peek(paint.getBlendMode());
         if (shaderContext) {
             fBuffer.reset(info.width());
         } else {
             fPM4f = SkColor4f::FromColor(paint.getColor()).premul();
         }
         fFlags = 0;
     }
 
     SkXfermode*             fXfer;
     SkPM4f                  fPM4f;
@@ skipping 64 matching lines @@
 
 template <typename State> SkBlitter* create(const SkPixmap& device, const SkPaint& paint,
                                             SkShader::Context* shaderContext,
                                             SkTBlitterAllocator* allocator) {
     SkASSERT(allocator != nullptr);
 
     if (shaderContext) {
         SkShader::Context::BlitState bstate;
         sk_bzero(&bstate, sizeof(bstate));
         bstate.fCtx = shaderContext;
-        bstate.fXfer = paint.getXfermode();
+        bstate.fXfer = SkXfermode::Peek(paint.getBlendMode());
 
         (void)shaderContext->chooseBlitProcs(device.info(), &bstate);
         return allocator->createT<SkState_Shader_Blitter<State>>(device, paint, bstate);
     } else {
         SkColor color = paint.getColor();
         if (0 == SkColorGetA(color)) {
             return nullptr;
         }
         return allocator->createT<SkState_Blitter<State>>(device, paint);
     }
 }
 
 SkBlitter* SkBlitter_ARGB32_Create(const SkPixmap& device, const SkPaint& paint,
                                    SkShader::Context* shaderContext,
                                    SkTBlitterAllocator* allocator) {
     return create<State32>(device, paint, shaderContext, allocator);
 }
 
 SkBlitter* SkBlitter_F16_Create(const SkPixmap& device, const SkPaint& paint,
                                 SkShader::Context* shaderContext,
                                 SkTBlitterAllocator* allocator) {
     return create<StateF16>(device, paint, shaderContext, allocator);
 }