Use SkPngEncoder in gfx jpeg_codec

ui/gfx/codec/codec_priv.h

Index: ui/gfx/codec/codec_priv.h
diff --git a/ui/gfx/codec/codec_priv.h b/ui/gfx/codec/codec_priv.h
new file mode 100644
index 0000000000000000000000000000000000000000..e3275a3ee5a4c9e77a104f7eb83f6a09a5e1caef
--- /dev/null
+++ b/ui/gfx/codec/codec_priv.h
@@ -0,0 +1,34 @@
+// 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.
+
+#ifndef UI_GFX_CODEC_PRIV_CODEC_H_
+#define UI_GFX_CODEC_PRIV_CODEC_H_
+
+#include <stddef.h>
+
+#include <vector>
+
+#include "base/logging.h"
+#include "third_party/skia/include/core/SkStream.h"
+
+namespace gfx {
+
+class VectorWStream : public SkWStream {

[scroggo_chromium, 2017/06/16 18:56:51]

Are you planning to put more stuff in here? Maybe this should just be
vector_wstream.h?

[liyuqian, 2017/06/23 13:54:25]

Done.

+ public:
+  VectorWStream(std::vector<unsigned char>* dst) : dst_(dst) {

[scroggo_chromium, 2017/06/16 18:56:51]

Maybe comment here that it does not take ownership?

[liyuqian, 2017/06/23 13:54:25]

Done.

+    DCHECK(dst_);
+    DCHECK_EQ(0UL, dst_->size());
+  }
+
+  bool write(const void* buffer, size_t size) override;
+
+  size_t bytesWritten() const override;
+
+ private:
+  // Does not have ownership.
+  std::vector<unsigned char>* dst_;
+};
+}

[Elliot Glaysher, 2017/06/16 19:08:11]

newline before '}', and also, add "  // namespace gfx"

[liyuqian, 2017/06/23 13:54:25]

Done.

+
+#endif

[Elliot Glaysher, 2017/06/16 19:08:11]

Header guard comment. // UI_GFX_CODEC_PRIV_CODEC_H_

[liyuqian, 2017/06/23 13:54:25]

Done.