sdefresne@ you are marked as an owner for translate.  Can you triage?

+yana as FYI

Anton, do you have any insight into what can be causing this language detection issue?

Hi Yana, thanks for pointing this out. Yes, we are aware of this issue and it will be fixed in the next release.

Is there already a tracker for this known issue we can follow? Is this already fixed on canary?

The issue is described in more detail here:
https://bugs.chromium.org/p/chromium/issues/detail?id=684609

The solution is a 2-part CL. I am awaiting a codereview for the first part:
https://codereview.chromium.org/2652023002

FYI #8 addresses the underlying issue, but the specific issue regarding triggering for zh-TW users visiting a zh-TW website was fixed and is in 56.2924.80 and later.

There are probably only iOS reports about this because it looks like iOS released 56.2924.79 while all other platforms (Windows, Linux, MacOS, Android) released 56.2924.87.

@riesa - Can you please link to the bug that tracked the fix/merge that was included in 56...87?

https://bugs.chromium.org/p/chromium/issues/detail?id=683164

Thank you!

Sharon can you please confirm this issue no longer repro's in M57?

Is it possible to provide a traditional Chinese website for me to test. All websites I tested seems to be in simplified Chinese. 
tw.yahoo.com
qq.com
baidu.com

Tested in 57.0.2987.50 dev and 58.0.3019.0 canary, iPhone 6+ iOS 10.2, iPad mini 10.1
wretch.cc
eyny.com
gamer.com.tw
Chrome still considers webpage in traditional Chinese as in simplified Chinese and this info-bar is prompt: "This page is in chinese(simplified)..."

Hi Sharon, did you try this with display language set to Traditional Chinese? The issue is that zh-Hant users are getting prompted for zh-Hant pages on versions at 56.0.2924.79 and earlier; they shouldn't be getting the prompt at version 56.0.2924.80 and later.

The *separate* issue of LangID identifying a zh-Hant page as zh-Hans is another bug, but is less serious as it does not affect the translation.

When device language is set to traditional Chinese:
wretch.cc
eyny.com
gamer.com.tw
Tested in 57.0.2987.68 dev iPhone 6+ iOS 10.2, iPad mini 10.1
Info-bar is displayed

Tested in 58.0.3019.0 canary iPhone 6+ iOS 10.2, iPad mini 10.1
Info-bar doesn't display

https://drive.google.com/a/google.com/file/d/0B3EcbqLuR5TLN1l2TS1xTmVXSjg/view

We are observing this issue on M57 - Android (Play Store reviews) as well.
Should it fork into another bug ?

It's fixed now (in M58). See 684609 and 699370.