Xiyuan, can I take this issue if you have not started yet?

Sure. I have not started on it.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/377ca77ed026cd7e281fe8d915e109411ac065da

commit 377ca77ed026cd7e281fe8d915e109411ac065da
Author: yoshiki <yoshiki@chromium.org>
Date: Thu Sep 29 01:50:10 2016

Migrate ArcBitmap to use typemapping

BUG= 643050 
TEST=manual test: notification small icons show in the tray correctly
TEST=Autotest cheets_NotificationTest passes

Review-Url: https://codereview.chromium.org/2308663002
Cr-Commit-Position: refs/heads/master@{#421712}

[modify] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/components/arc/BUILD.gn
[add] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/components/arc/bitmap/OWNERS
[add] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/components/arc/bitmap/bitmap_struct_traits.cc
[add] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/components/arc/bitmap/bitmap_struct_traits.h
[delete] https://crrev.com/5a139ba8b5636e7196714b4132b9240b18579ed3/components/arc/bitmap/bitmap_type_converters.cc
[delete] https://crrev.com/5a139ba8b5636e7196714b4132b9240b18579ed3/components/arc/bitmap/bitmap_type_converters.h
[add] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/components/arc/common/bitmap.typemap
[modify] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/components/arc/common/typemaps.gni
[modify] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/ui/arc/BUILD.gn
[modify] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/ui/arc/notification/arc_custom_notification_item.cc
[modify] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/ui/arc/notification/arc_custom_notification_item.h
[modify] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/ui/arc/notification/arc_notification_item.cc
[modify] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/ui/arc/notification/arc_notification_item.h
[modify] https://crrev.com/377ca77ed026cd7e281fe8d915e109411ac065da/ui/arc/notification/arc_notification_manager.cc

cheets_NotificationTest passes