change pixel-serializer to support reencoding existing data

tools/sk_tool_utils.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef sk_tool_utils_DEFINED
 #define sk_tool_utils_DEFINED
 
@@ skipping 97 matching lines @@
         sk_tool_utils::draw_checkerboard(canvas, 0xFF999999, 0xFF666666, 8);
     }
 
     SkBitmap create_string_bitmap(int w, int h, SkColor c, int x, int y,
                                   int textSize, const char* str);
 
     // Encodes to PNG, unless there is already encoded data, in which case that gets
     // used.
     class PngPixelSerializer : public SkPixelSerializer {
     public:
-        bool onUseEncodedData(const void*, size_t) override { return true; }
         SkData* onEncodePixels(const SkImageInfo& info, const void* pixels,
                                size_t rowBytes) override {
             return SkImageEncoder::EncodeData(info, pixels, rowBytes,
                                               SkImageEncoder::kPNG_Type, 100);
         }
     };
 
     // A helper for inserting a drawtext call into a SkTextBlobBuilder
     void add_to_text_blob(SkTextBlobBuilder* builder, const char* text, const SkPaint& origPaint,
                           SkScalar x, SkScalar y);
 
     void create_hemi_normal_map(SkBitmap* bm, const SkIRect& dst);
 
     void create_frustum_normal_map(SkBitmap* bm, const SkIRect& dst);
 
     void create_tetra_normal_map(SkBitmap* bm, const SkIRect& dst);
 
 }  // namespace sk_tool_utils
 
 #endif  // sk_tool_utils_DEFINED