Simplify flattening to just write enough to call the factory

src/effects/SkColorMatrixFilter.cpp

Index: src/effects/SkColorMatrixFilter.cpp
diff --git a/src/effects/SkColorMatrixFilter.cpp b/src/effects/SkColorMatrixFilter.cpp
index d76502e239afafe16425243ae036594c4c36f386..f62e0f146233b030ebf0474b25695a85dde2facb 100644
--- a/src/effects/SkColorMatrixFilter.cpp
+++ b/src/effects/SkColorMatrixFilter.cpp
@@ -303,18 +303,26 @@ void SkColorMatrixFilter::filterSpan16(const uint16_t src[], int count,
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkColorMatrixFilter::flatten(SkWriteBuffer& buffer) const {
-    this->INHERITED::flatten(buffer);
     SkASSERT(sizeof(fMatrix.fMat)/sizeof(SkScalar) == 20);
     buffer.writeScalarArray(fMatrix.fMat, 20);
 }
 
-SkColorMatrixFilter::SkColorMatrixFilter(SkReadBuffer& buffer)
-        : INHERITED(buffer) {
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+SkColorMatrixFilter::SkColorMatrixFilter(SkReadBuffer& buffer) : INHERITED(buffer) {
     SkASSERT(buffer.getArrayCount() == 20);
     if (buffer.readScalarArray(fMatrix.fMat, 20)) {
         this->initState(fMatrix.fMat);
     }
 }
+#endif
+
+SkFlattenable* SkColorMatrixFilter::CreateProc(SkReadBuffer& buffer) {
+    SkColorMatrix matrix;
+    if (buffer.readScalarArray(matrix.fMat, 20)) {
+        return Create(matrix);
+    }
+    return NULL;
+}
 
 bool SkColorMatrixFilter::asColorMatrix(SkScalar matrix[20]) const {
     if (matrix) {