Simplify flattening to just write enough to call the factory

src/effects/SkLerpXfermode.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 "SkLerpXfermode.h"
 #include "SkColorPriv.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkString.h"
 
 SkXfermode* SkLerpXfermode::Create(SkScalar scale) {
     int scale256 = SkScalarRoundToInt(scale * 256);
     if (scale256 >= 256) {
         return SkXfermode::Create(SkXfermode::kSrc_Mode);
     } else if (scale256 <= 0) {
         return SkXfermode::Create(SkXfermode::kDst_Mode);
     }
     return SkNEW_ARGS(SkLerpXfermode, (scale256));
 }
 
 SkLerpXfermode::SkLerpXfermode(unsigned scale256) : fScale256(scale256) {}
 
-SkLerpXfermode::SkLerpXfermode(SkReadBuffer& buffer)
-    : INHERITED(buffer) {
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+SkLerpXfermode::SkLerpXfermode(SkReadBuffer& buffer) : INHERITED(buffer) {
     fScale256 = buffer.readUInt();
 }
+#endif
 
 void SkLerpXfermode::flatten(SkWriteBuffer& buffer) const {
-    this->INHERITED::flatten(buffer);
     buffer.writeUInt(fScale256);
 }
 
+SkFlattenable* SkLerpXfermode::CreateProc(SkReadBuffer& buffer) {
+    return SkNEW_ARGS(SkLerpXfermode, (buffer.readUInt()));
+}
+
 void SkLerpXfermode::xfer32(SkPMColor dst[], const SkPMColor src[], int count,
                              const SkAlpha aa[]) const {
     const int scale = fScale256;
 
     if (aa) {
         for (int i = 0; i < count; ++i) {
             unsigned a = aa[i];
             if (a) {
                 SkPMColor dstC = dst[i];
                 SkPMColor resC = SkFastFourByteInterp256(src[i], dstC, scale);
@@ skipping 56 matching lines @@
             dst[i] = SkAlphaBlend(SkGetPackedA32(src[i]), dst[i], scale);
         }
     }
 }
 
 #ifndef SK_IGNORE_TO_STRING
 void SkLerpXfermode::toString(SkString* str) const {
     str->printf("SkLerpXfermode: scale: %g", fScale256 / 256.0);
 }
 #endif