Simplify flattening to just write enough to call the factory

src/effects/SkDisplacementMapEffect.cpp

Index: src/effects/SkDisplacementMapEffect.cpp
diff --git a/src/effects/SkDisplacementMapEffect.cpp b/src/effects/SkDisplacementMapEffect.cpp
index a6897ea89157e51ff2ec6a72f325e08dd7b6a938..8d106e4bdc06532575bad10e4947b8585a7bf4be 100644
--- a/src/effects/SkDisplacementMapEffect.cpp
+++ b/src/effects/SkDisplacementMapEffect.cpp
@@ -174,6 +174,7 @@ SkDisplacementMapEffect::SkDisplacementMapEffect(ChannelSelectorType xChannelSel
 SkDisplacementMapEffect::~SkDisplacementMapEffect() {
 }
 
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
 SkDisplacementMapEffect::SkDisplacementMapEffect(SkReadBuffer& buffer)
   : INHERITED(2, buffer)
 {
@@ -184,9 +185,21 @@ SkDisplacementMapEffect::SkDisplacementMapEffect(SkReadBuffer& buffer)
                     channel_selector_type_is_valid(fYChannelSelector) &&
                     SkScalarIsFinite(fScale));
 }
+#endif
+
+SkFlattenable* SkDisplacementMapEffect::CreateProc(SkReadBuffer& buffer) {
+    Common common;
+    if (!common.unflatten(buffer, 2)) {
+        return NULL;
+    }
+    ChannelSelectorType xsel = (ChannelSelectorType)buffer.readInt();
+    ChannelSelectorType ysel = (ChannelSelectorType)buffer.readInt();
+    SkScalar scale = buffer.readScalar();
+    return Create(xsel, ysel, scale, common.inputAt(0), common.inputAt(1), &common.cropRect());
+}
 
 void SkDisplacementMapEffect::flatten(SkWriteBuffer& buffer) const {
-    this->INHERITED::flatten(buffer);
+    this->flattenCommon(buffer);
     buffer.writeInt((int) fXChannelSelector);
     buffer.writeInt((int) fYChannelSelector);
     buffer.writeScalar(fScale);