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

src/effects/SkArithmeticMode.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkArithmeticModePriv.h"
 #include "SkColorPriv.h"
 #include "SkNx.h"
@@ skipping 21 matching lines @@
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkArithmeticMode_scalar)
 
 #if SK_SUPPORT_GPU
     sk_sp<GrFragmentProcessor> makeFragmentProcessorForImageFilter(
                                                 sk_sp<GrFragmentProcessor> dst) const override;
     sk_sp<GrXPFactory> asXPFactory() const override;
 #endif
 
+    bool isArithmetic(SkArithmeticParams* params) const override {
+        if (params) {
+            memcpy(params->fK, fK, 4 * sizeof(float));
+            params->fEnforcePMColor = fEnforcePMColor;
+        }
+        return true;
+    }
+
 private:
     void flatten(SkWriteBuffer& buffer) const override {
         buffer.writeScalar(fK[0]);
         buffer.writeScalar(fK[1]);
         buffer.writeScalar(fK[2]);
         buffer.writeScalar(fK[3]);
         buffer.writeBool(fEnforcePMColor);
     }
 
     SkScalar fK[4];
@@ skipping 92 matching lines @@
                                        SkScalarToFloat(fK[2]),
                                        SkScalarToFloat(fK[3]),
                                        fEnforcePMColor);
 }
 
 #endif
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkArithmeticMode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkArithmeticMode_scalar)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END