Able to reproduce the issue on chrome reported version 66.0.3359.139 and on latest chrome stable 66.0.3359.181 using Ubuntu 17.10 and Windows 10 and on latest chrome# 68.0.3432.0. As the issue is seen from M-60(60.0.3112.0) considering this issue as Non-Regression and marking it as untriage.
Note: This issue is not seen on Mac.

Thanks!

Sounds like some kind of issue in how we do font rendering.

Mike, do you know what the right component/owner is for this?

 Issue 865742  has been merged into this issue.

See additional cases on duped-in bug.

Sorry, I don't believe anyone has been consistently working on RenderText.
tapted fixed  Issue 851241 , but I feel like Trent has a lot on his plate.
ccameron is working on Issue 862773, but that's more specific to Mac.
There are lots of open and one-off assigned RenderText bugs out there.
It would be nice if someone was concertedly working on views/gfx text code.

This will regress on Mac in m69. And in a worse way :/. On Mac, the butterfly is blank rather than getting a "tofu" square.

I'm timeboxing an ~hour to investigate.

Seems straightforward.. https://chromium-review.googlesource.com/1146401

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ac7c259316c75aad05150d0a5948787efd9e1803

commit ac7c259316c75aad05150d0a5948787efd9e1803
Author: Trent Apted <tapted@chromium.org>
Date: Mon Jul 23 23:55:16 2018

RenderTextHarfBuzz: treat 「」 as brackets.

Brackets have the "common script" unicode property and need special handling
when breaking runs (see http://www.unicode.org/reports/tr24/#Common ).

Currently, emoji breaks runs correctly around other bracket and quote mark
types, but not around 「」, which is commonly used in CJK languages.

Bug:  843426 ,  396776 
Change-Id: Ia5ff5165d5c260aa1876488e2f51d566f2164cd6
Reviewed-on: https://chromium-review.googlesource.com/1146401
Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577345}
[modify] https://crrev.com/ac7c259316c75aad05150d0a5948787efd9e1803/ui/gfx/render_text_harfbuzz.cc
[modify] https://crrev.com/ac7c259316c75aad05150d0a5948787efd9e1803/ui/gfx/render_text_unittest.cc

Requesting a merge for r577345. This fixes the most commonly used quote mark for Japanese, and per #c8 this is worse on Mac since we don't get "tofu". Tested 70.0.3501.2 and the fix is working as intended.

But I've done a bit more research, and I think we need a more generic fix. Filed  Issue 867196 .

Your change meets the bar and is auto-approved for M69. Please go ahead and merge the CL to branch 3497 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), kariahda@(iOS), cindyb@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2638fac865d4f1debec5064f78e87b9a793c9653

commit 2638fac865d4f1debec5064f78e87b9a793c9653
Author: Trent Apted <tapted@chromium.org>
Date: Thu Jul 26 00:34:42 2018

[merge-m69] RenderTextHarfBuzz: treat 「」 as brackets.

Brackets have the "common script" unicode property and need special handling
when breaking runs (see http://www.unicode.org/reports/tr24/#Common ).

Currently, emoji breaks runs correctly around other bracket and quote mark
types, but not around 「」, which is commonly used in CJK languages.

TBR=tapted@chromium.org

(cherry picked from commit ac7c259316c75aad05150d0a5948787efd9e1803)

Bug:  843426 ,  396776 
Change-Id: Ia5ff5165d5c260aa1876488e2f51d566f2164cd6
Reviewed-on: https://chromium-review.googlesource.com/1146401
Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Trent Apted <tapted@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#577345}
Reviewed-on: https://chromium-review.googlesource.com/1150017
Reviewed-by: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/branch-heads/3497@{#97}
Cr-Branched-From: 271eaf50594eb818c9295dc78d364aea18c82ea8-refs/heads/master@{#576753}
[modify] https://crrev.com/2638fac865d4f1debec5064f78e87b9a793c9653/ui/gfx/render_text_harfbuzz.cc
[modify] https://crrev.com/2638fac865d4f1debec5064f78e87b9a793c9653/ui/gfx/render_text_unittest.cc

Fixed, but more follow-up in  Issue 867196