Simplify flattening to just write enough to call the factory

src/effects/SkDropShadowImageFilter.cpp

Index: src/effects/SkDropShadowImageFilter.cpp
diff --git a/src/effects/SkDropShadowImageFilter.cpp b/src/effects/SkDropShadowImageFilter.cpp
index c79cf0bcd39bf580930a19a35266dbfa0a90b096..858e657de31f593e233564a3fe0102329c81568e 100644
--- a/src/effects/SkDropShadowImageFilter.cpp
+++ b/src/effects/SkDropShadowImageFilter.cpp
@@ -38,6 +38,7 @@ SkDropShadowImageFilter::SkDropShadowImageFilter(SkScalar dx, SkScalar dy,
 {
 }
 
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
 SkDropShadowImageFilter::SkDropShadowImageFilter(SkReadBuffer& buffer)
  : INHERITED(1, buffer) {
     fDx = buffer.readScalar();
@@ -50,10 +51,23 @@ SkDropShadowImageFilter::SkDropShadowImageFilter(SkReadBuffer& buffer)
                     SkScalarIsFinite(fSigmaX) &&
                     SkScalarIsFinite(fSigmaY));
 }
+#endif
 
-void SkDropShadowImageFilter::flatten(SkWriteBuffer& buffer) const
-{
-    this->INHERITED::flatten(buffer);
+SkFlattenable* SkDropShadowImageFilter::CreateProc(SkReadBuffer& buffer) {
+    Common common;
+    if (!common.unflatten(buffer, 1)) {
+        return NULL;
+    }
+    SkScalar dx = buffer.readScalar();
+    SkScalar dy = buffer.readScalar();
+    SkScalar sigmaX = buffer.readScalar();
+    SkScalar sigmaY = buffer.readScalar();
+    SkColor color = buffer.readColor();
+    return Create(dx, dy, sigmaX, sigmaY, color);
+}
+
+void SkDropShadowImageFilter::flatten(SkWriteBuffer& buffer) const {
+    this->flattenCommon(buffer);
     buffer.writeScalar(fDx);
     buffer.writeScalar(fDy);
     buffer.writeScalar(fSigmaX);