The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b7a62ba52e486ed6ddd3743292893d8f10fb147c

commit b7a62ba52e486ed6ddd3743292893d8f10fb147c
Author: Yoichi Osato <yoichio@chromium.org>
Date: Thu Sep 27 02:27:50 2018

Clean up layout_selection.cc local functions.

This patch extracts MarkSelected at call sites since the function
used to be called not directly because of LayoutTextFragment.

This patch also shrinks ComputeNewPaintRange not to bring a hashset.
Then the hashset appears only at one function.

Bug: 889360

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng
Change-Id: I44a020ccf9172c6159bec5251a3ab3733b7d4868
Reviewed-on: https://chromium-review.googlesource.com/1244699
Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594568}
[modify] https://crrev.com/b7a62ba52e486ed6ddd3743292893d8f10fb147c/third_party/blink/renderer/core/editing/layout_selection.cc