add helpers for using SkData with picture serialization

dm/DMSrcSink.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "DMSrcSink.h"
 #include "Resources.h"
 #include "SkAndroidCodec.h"
@@ skipping 1410 matching lines @@
     auto size = src.size();
     SkPictureRecorder recorder;
     Error err = src.draw(recorder.beginRecording(SkIntToScalar(size.width()),
                                                  SkIntToScalar(size.height())));
     if (!err.isEmpty()) {
         return err;
     }
     sk_sp<SkPicture> pic(recorder.finishRecordingAsPicture());
 
     // Serialize it and then deserialize it.
-    SkDynamicMemoryWStream wStream;
-    pic->serialize(&wStream);
-    SkAutoTDelete<SkStream> rStream(wStream.detachAsStream());
-    sk_sp<SkPicture> deserialized(SkPicture::MakeFromStream(rStream));
+    sk_sp<SkPicture> deserialized(SkPicture::MakeFromData(pic->serialize().get()));
 
     return draw_to_canvas(fSink, bitmap, stream, log, size, [&](SkCanvas* canvas) {
         canvas->drawPicture(deserialized);
         return check_against_reference(bitmap, src, fSink);
     });
 }
 
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
 ViaTiles::ViaTiles(int w, int h, SkBBHFactory* factory, Sink* sink)
@@ skipping 217 matching lines @@
         Error err = src.draw(&rec);
         if (!err.isEmpty()) {
             return err;
         }
         dl->draw(canvas);
         return check_against_reference(bitmap, src, fSink);
     });
 }
 
 }  // namespace DM