force readbuffer clients to use specialized readFoo for flattenables

src/image/SkDataPixelRef.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDataPixelRef.h"
 #include "SkData.h"
 #include "SkFlattenableBuffers.h"
@@ skipping 16 matching lines @@
     // nothing to do
 }
 
 void SkDataPixelRef::flatten(SkFlattenableWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writeFlattenable(fData);
 }
 
 SkDataPixelRef::SkDataPixelRef(SkFlattenableReadBuffer& buffer)
         : INHERITED(buffer, NULL) {
-    fData = (SkData*)buffer.readFlattenable();
+    fData = buffer.readData();
     this->setPreLocked(const_cast<void*>(fData->data()), NULL);
 }