Revert of Remove SK_SUPPORT_LEGACY_DEEPFLATTENING.

src/effects/SkDisplacementMapEffect.cpp

Index: src/effects/SkDisplacementMapEffect.cpp
diff --git a/src/effects/SkDisplacementMapEffect.cpp b/src/effects/SkDisplacementMapEffect.cpp
index d39240e012bdd8ee84d31f72885e543f75e91907..edae0441f4dbbc5e0530b4c6df7a863f15fc2ff4 100644
--- a/src/effects/SkDisplacementMapEffect.cpp
+++ b/src/effects/SkDisplacementMapEffect.cpp
@@ -192,6 +192,19 @@
 SkDisplacementMapEffect::~SkDisplacementMapEffect() {
 }
 
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+SkDisplacementMapEffect::SkDisplacementMapEffect(SkReadBuffer& buffer)
+  : INHERITED(2, buffer)
+{
+    fXChannelSelector = (SkDisplacementMapEffect::ChannelSelectorType) buffer.readInt();
+    fYChannelSelector = (SkDisplacementMapEffect::ChannelSelectorType) buffer.readInt();
+    fScale            = buffer.readScalar();
+    buffer.validate(channel_selector_type_is_valid(fXChannelSelector) &&
+                    channel_selector_type_is_valid(fYChannelSelector) &&
+                    SkScalarIsFinite(fScale));
+}
+#endif
+
 SkFlattenable* SkDisplacementMapEffect::CreateProc(SkReadBuffer& buffer) {
     SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 2);
     ChannelSelectorType xsel = (ChannelSelectorType)buffer.readInt();