https://chromium-review.googlesource.com/c/chromium/src/+/956652

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e79de99d68bb8bb066362743c635ec14b9bc2e87

commit e79de99d68bb8bb066362743c635ec14b9bc2e87
Author: qi1988.yang <qi1988.yang@samsung.com>
Date: Mon Mar 12 08:05:17 2018

Use base::Optional instead of ImageView::image_size_set_

As close as possible to the C++17 standard, use std::Optional.

Bug:  805207 

Signed-off-by: qi1988.yang <qi1988.yang@samsung.com>
Change-Id: I88560f320ad38b986eb84a73e488eb4968ea1660
Reviewed-on: https://chromium-review.googlesource.com/956652
Reviewed-by: Trent Apted <tapted@chromium.org>
Commit-Queue: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542441}
[modify] https://crrev.com/e79de99d68bb8bb066362743c635ec14b9bc2e87/ui/views/controls/image_view.cc
[modify] https://crrev.com/e79de99d68bb8bb066362743c635ec14b9bc2e87/ui/views/controls/image_view.h