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/ImageFilterTest.cpp b/tests/ImageFilterTest.cpp
index ee3de50..214aed9 100644
--- a/tests/ImageFilterTest.cpp
+++ b/tests/ImageFilterTest.cpp
@@ -56,12 +56,15 @@
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(MatrixTestImageFilter)
 
 protected:
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
     explicit MatrixTestImageFilter(SkReadBuffer& buffer) : SkImageFilter(0, NULL) {
         fReporter = static_cast<skiatest::Reporter*>(buffer.readFunctionPtr());
         buffer.readMatrix(&fExpectedMatrix);
     }
+#endif
 
     virtual void flatten(SkWriteBuffer& buffer) const SK_OVERRIDE {
+        this->INHERITED::flatten(buffer);
         buffer.writeFunctionPtr(fReporter);
         buffer.writeMatrix(fExpectedMatrix);
     }
@@ -69,10 +72,20 @@
 private:
     skiatest::Reporter* fReporter;
     SkMatrix fExpectedMatrix;
+    
+    typedef SkImageFilter INHERITED;
 };
 
 }
 
+SkFlattenable* MatrixTestImageFilter::CreateProc(SkReadBuffer& buffer) {
+    SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
+    skiatest::Reporter* reporter = (skiatest::Reporter*)buffer.readFunctionPtr();
+    SkMatrix matrix;
+    buffer.readMatrix(&matrix);
+    return SkNEW_ARGS(MatrixTestImageFilter, (reporter, matrix));
+}
+
 static void make_small_bitmap(SkBitmap& bitmap) {
     bitmap.allocN32Pixels(kBitmapSize, kBitmapSize);
     SkCanvas canvas(bitmap);