Use SkPngEncoder in gfx jpeg_codec

ui/gfx/codec/vector_wstream.cc

+// Copyright (c) 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/gfx/codec/vector_wstream.h"
+
+namespace gfx {
+
+bool VectorWStream::write(const void* buffer, size_t size) {
+  const unsigned char* ptr = reinterpret_cast<const unsigned char*>(buffer);
+  dst_->insert(dst_->end(), ptr, ptr + size);
+  return true;
+}
+
+size_t VectorWStream::bytesWritten() const {
+  return dst_->size();
+}
+
+}  // namespace gfx