Simplify flattening to just write enough to call the factory

src/effects/SkBlurMaskFilter.cpp

Index: src/effects/SkBlurMaskFilter.cpp
diff --git a/src/effects/SkBlurMaskFilter.cpp b/src/effects/SkBlurMaskFilter.cpp
index 4ab9944d8ca2ce573b3898c64bee64232cbfbbee..7204954d906c2642d92675c0a26ab24ded086ecd 100644
--- a/src/effects/SkBlurMaskFilter.cpp
+++ b/src/effects/SkBlurMaskFilter.cpp
@@ -522,19 +522,29 @@ void SkBlurMaskFilterImpl::computeFastBounds(const SkRect& src,
              src.fRight + pad, src.fBottom + pad);
 }
 
-SkBlurMaskFilterImpl::SkBlurMaskFilterImpl(SkReadBuffer& buffer)
-        : SkMaskFilter(buffer) {
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+SkBlurMaskFilterImpl::SkBlurMaskFilterImpl(SkReadBuffer& buffer) : SkMaskFilter(buffer) {
     fSigma = buffer.readScalar();
     fBlurStyle = (SkBlurStyle)buffer.readInt();
     fBlurFlags = buffer.readUInt() & SkBlurMaskFilter::kAll_BlurFlag;
     SkASSERT(fSigma > 0);
     SkASSERT((unsigned)fBlurStyle <= kLastEnum_SkBlurStyle);
 }
+#endif
+
+SkFlattenable* SkBlurMaskFilterImpl::CreateProc(SkReadBuffer& buffer) {
+    const SkScalar sigma = buffer.readScalar();
+    const unsigned style = buffer.readUInt();
+    const unsigned flags = buffer.readUInt();
+    if (style <= kLastEnum_SkBlurStyle) {
+        return SkBlurMaskFilter::Create((SkBlurStyle)style, sigma, flags);
+    }
+    return NULL;
+}
 
 void SkBlurMaskFilterImpl::flatten(SkWriteBuffer& buffer) const {
-    this->INHERITED::flatten(buffer);
     buffer.writeScalar(fSigma);
-    buffer.writeInt(fBlurStyle);
+    buffer.writeUInt(fBlurStyle);
     buffer.writeUInt(fBlurFlags);
 }