martiw@ could you PTAL.

Marti, can you please check this for M63 asap? This is a regression in 63. I have cc'ed Eric and Rohit in case they know of another change that would have introduced this in omnibox suggest in 63.

Indeed, I could reproduce this issue on 62.0.03202.70 on iPhone 7+ with iOS 11.1 (15B93).

My repro steps:
Precondition: Disable New Gen Bookmarks from chrome://flags, and I have a bookmark folder.
1. Launch Google Chrome
2. Tap Menu -> Bookmarks
3. Tap the "3 dots" button of the bookmark folder, Tap on Edit, Rename the folder as "THIS_IS_FOLDER"
4. Dismiss Bookmarks UI screen
5. Focus on omnibox and start typing the name give in step#3, THIS_IS_FOLDER

It seems "Folder Renaming" is the root cause. 

In new gen bookmarks, folder will be created as "New Folder" and *Renamed* after user entered the folder name.
In old bookmarks, folder can be *Renamed* only by the edit page after folder creation.

This issue could be reproduced on Chrome Mac version as well (62.0.3202.75).
It seems the root cause is:
SetTitle() of bookmark_model.cc (which is shared among all platforms) will cause the folder name to appear in DoAutocomplete() of bookmark_provider.cc (also cross-platforms).
So this bug might also happen in Android.

This is not a regression and it seems this should not be a RBS.
And the code is out of my reach.

noyau@, sdefresne@, should we assign this to the owner of bookmark_model.cc or bookmark_provider.cc?

thx.

Adding Mac OS

M63 Stable promotion is coming soon and your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and request a merge to M63 ASAP. Thank you.

Same issue could be reproduced on Clank 61.0.3163.98.  see attached png.
This bug could be reproduced on Bling 61.0.3163.73 and 62.0.3202.70.

In summary, this bug happen when:
1. Android: renaming folder.
2. Mac: creating folder.
3. old iOS bookmark: renaming folder.
4. new iOS bookmark: creating folder.

And when typed first 3 chars of the folder name in omnibox, suggestion list will:
1: show a blank line, nothing happen when click on it.
2,3,4: show the folder name, nothing happen when click on it.

Since this bug happened long time ago (m61 or earlier), I removed ReleaseBlock-Stable. 
 Pls add it back if you think it is a mistake.

Hi mattreynolds@, could you PTAL?

It seems SetTitle() of bookmark_model.cc mistakenly cause the bookmark folder name to appear in DoAutocomplete() of bookmark_provider.cc.

re comment #10: I just independently reached the same conclusion.  We need to guard lines 359 and 361 with an is_url() check.
https://cs.chromium.org/chromium/src/components/bookmarks/browser/bookmark_model.cc?l=359

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e33ab140cbeb0f47d42ccfb4d2d6c5140946e501

commit e33ab140cbeb0f47d42ccfb4d2d6c5140946e501
Author: Matt Reynolds <mattreynolds@google.com>
Date: Thu Nov 09 03:06:48 2017

Avoid adding bookmark folder to index on rename

The BookmarkModel maintains an index of bookmark titles and URLs for
quick lookup by the omnibox autocomplete provider. Bookmark folders
should be excluded from this index to prevent them from appearing as
autocomplete suggestions. However, there was a bug that caused a
bookmark folder to be added to the index when the folder is renamed,
allowing it to appear as a (useless) autocomplete suggestion. This CL
checks to ensure that only URL nodes are added to the index.

BUG= 778266 

Change-Id: Ie24fe0f7a8c4ef7ea6327683eb3d5a5d175250eb
Reviewed-on: https://chromium-review.googlesource.com/757543
Commit-Queue: Matt Reynolds <mattreynolds@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515079}
[modify] https://crrev.com/e33ab140cbeb0f47d42ccfb4d2d6c5140946e501/components/bookmarks/browser/bookmark_model.cc
[modify] https://crrev.com/e33ab140cbeb0f47d42ccfb4d2d6c5140946e501/components/bookmarks/browser/bookmark_model_unittest.cc

Tested in the following Build , this issue is not fixed.

Build: 63.0.3239.48 beta, 64.0.3267.0 Canary
iOS: 10.3.3, 11.1.1, 11.2
Version: iPhone 7, iPhone 8, iPad

I tried this with Chrome ToT in a simulator (iPhone 8 Plus) and couldn't repro the bug. I also tried with Chrome Canary (64.0.3267.0 canary) on iPhone 6s and couldn't repro. I used these steps:

0. Open Chrome
1. Open the Mobile Bookmarks dialog (... -> Bookmarks, tap Mobile Bookmarks)
2. Tap New Folder, name it "HE_HE_HE", tap Done
3. Tap Select, tap the radio button next to HE_HE_HE, then "More...", then "Edit Folder"
4. Edit title to "HE_HE", tap Done
5. Tap Done to exit Bookmarks
6. Tap omnibox, type "HE_" and observe the list of autocomplete suggestions

Expected:

HE_HE should not appear.

I noticed after attempting this a few times that I started seeing a HE_HE suggestion, which is OK if it comes from the search provider. You can determine which provider it came from by tapping it; the search suggestion navigates to the search result page, while the buggy bookmark folder suggestion does nothing.

Could you test this again and verify that tapping the buggy suggestion does nothing?

Tested this bug today, the issue is fixed in the following Build

Build: 64.0.3269.0 Canary
iOS: 10.3.3, 11.2
Device: iPhone 8, iPhone 7+, iPad mini2

This needs to be merged to M63.

This bug requires manual review: Less than 15 days to go before AppStore submit on M63
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), gkihumba@(ChromeOS), govind@(Desktop)

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

cmasso@ (M63 Chrome on Andorid and iOS) TPM 

Thanks for fixing this issue. This is not critical to be merged into M63 and only critical issues should be considered to be merged into the branch at this point. 
I am rejecting the merge of this fix into M63 and feel free to ping me if I am missing something.