Simplify flattening to just write enough to call the factory

src/effects/SkLerpXfermode.cpp

Index: src/effects/SkLerpXfermode.cpp
diff --git a/src/effects/SkLerpXfermode.cpp b/src/effects/SkLerpXfermode.cpp
index c8389fea799c7fe5181cb065410dd5785134fb39..0376a57b64f0a2921d707123a11af1883413ab00 100644
--- a/src/effects/SkLerpXfermode.cpp
+++ b/src/effects/SkLerpXfermode.cpp
@@ -23,16 +23,20 @@ SkXfermode* SkLerpXfermode::Create(SkScalar scale) {
 
 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;