Enable flattening/unflattening with custom unflatten procs

src/core/SkValidatingReadBuffer.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkValidatingReadBuffer_DEFINED
 #define SkValidatingReadBuffer_DEFINED
 
@@ skipping 15 matching lines @@
     const void* skip(size_t size) override;
 
     // primitives
     bool readBool() override;
     SkColor readColor() override;
     int32_t readInt() override;
     SkScalar readScalar() override;
     uint32_t readUInt() override;
     int32_t read32() override;
 
+    // peek
+    uint8_t peekByte() override;
+
     // strings -- the caller is responsible for freeing the string contents
     void readString(SkString* string) override;
     void* readEncodedString(size_t* length, SkPaint::TextEncoding encoding) override;
 
     // common data structures
     SkFlattenable* readFlattenable(SkFlattenable::Type type) override;
     void skipFlattenable() override;
     void readPoint(SkPoint* point) override;
     void readMatrix(SkMatrix* matrix) override;
     void readIRect(SkIRect* rect) override;
@@ skipping 27 matching lines @@
     static bool IsPtrAlign4(const void* ptr) {
         return SkIsAlign4((uintptr_t)ptr);
     }
 
     bool fError;
 
     typedef SkReadBuffer INHERITED;
 };
 
 #endif // SkValidatingReadBuffer_DEFINED