Simplify flattening to just write enough to call the factory/public-constructor for the class. We want to *not* rely on private constructors, and not rely on calling through the inheritance hierarchy for either flattening or unflattening(CreateProc).

Refactoring pattern:

1. guard the existing constructor(readbuffer) with the legacy build-flag
2. If you are a instancable subclass, implement CreateProc(readbuffer) to create a new instances from the buffer params (or return NULL).

If you're a shader subclass
1. You must read/write the local matrix if your class accepts that in its factory/constructor, else ignore it.

R=robertphillips@google.com, mtklein@google.com, senorblanco@google.com, senorblanco@chromium.org, sugoi@chromium.org

Author: reed@google.com

Review URL: https://codereview.chromium.org/395603002
diff --git a/tests/LayerRasterizerTest.cpp b/tests/LayerRasterizerTest.cpp
index 640c581..4b236ac 100644
--- a/tests/LayerRasterizerTest.cpp
+++ b/tests/LayerRasterizerTest.cpp
@@ -33,11 +33,9 @@
 
     static int GetCount() { return gCount; }
 
-    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(DummyRasterizer)
+    SK_DECLARE_NOT_FLATTENABLE_PROCS(DummyRasterizer)
 
 private:
-    DummyRasterizer(SkReadBuffer&) {}
-
     static int gCount;
 
     typedef SkRasterizer INHERITED;