Simplify flattening to just write enough to call the factory

src/effects/SkDiscretePathEffect.cpp

Index: src/effects/SkDiscretePathEffect.cpp
diff --git a/src/effects/SkDiscretePathEffect.cpp b/src/effects/SkDiscretePathEffect.cpp
index f6f91124479404330b1763370a51a70deb44f76d..e8cc6a2f7032c779b6315d018247328104a5cf17 100644
--- a/src/effects/SkDiscretePathEffect.cpp
+++ b/src/effects/SkDiscretePathEffect.cpp
@@ -75,15 +75,24 @@ bool SkDiscretePathEffect::filterPath(SkPath* dst, const SkPath& src,
     return true;
 }
 
+SkFlattenable* SkDiscretePathEffect::CreateProc(SkReadBuffer& buffer) {
+    SkScalar segLength = buffer.readScalar();

[sugoi1, 2014/08/19 18:46:17]

Note: Looking at filterPath(), it seems like a very small value or a negative
value (through integer overflow of "n") of fSegLength could cause the "while
(--n >= 0)" to go for a very long time and hang.

[reed1, 2014/08/19 19:58:06]

Good note for future CL.

+    SkScalar perterb = buffer.readScalar();
+    uint32_t seed = buffer.readUInt();
+    return Create(segLength, perterb, seed);
+}
+
 void SkDiscretePathEffect::flatten(SkWriteBuffer& buffer) const {
-    this->INHERITED::flatten(buffer);
     buffer.writeScalar(fSegLength);
     buffer.writeScalar(fPerterb);
     buffer.writeUInt(fSeedAssist);
 }
 
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
 SkDiscretePathEffect::SkDiscretePathEffect(SkReadBuffer& buffer) {
     fSegLength = buffer.readScalar();
     fPerterb = buffer.readScalar();
     fSeedAssist = buffer.readUInt();
 }
+#endif
+