Remove (almost) unused read/writeFunctionPtr API.

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 27 matching lines @@
     int32_t read32() override;
 
     // peek
     uint8_t peekByte() override;
 
     // strings -- the caller is responsible for freeing the string contents
     void readString(SkString* string) 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;
     void readRect(SkRect* rect) override;
     void readRRect(SkRRect* rrect) override;
     void readRegion(SkRegion* region) override;
     void readPath(SkPath* path) override;
 
     // binary data and arrays
     bool readByteArray(void* value, size_t size) override;
@@ skipping 21 matching lines @@
     static bool IsPtrAlign4(const void* ptr) {
         return SkIsAlign4((uintptr_t)ptr);
     }
 
     bool fError;
 
     typedef SkReadBuffer INHERITED;
 };
 
 #endif // SkValidatingReadBuffer_DEFINED