Findit identified the culprit r578404 with confidence 70.0% in the config "chromium.linux / Linux Tests"
based on the flakiness trend:

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVywgELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCKLAWNocm9taXVtLmxpbnV4L0xpbnV4IFRlc3RzLzcxMzQ0L3Zpel9icm93c2VyX3Rlc3RzL1YyVmlVblJqUkdWemEzUnZjRU5oY0hSMWNtVkNjbTkzYzJWeVZHVnpkQzVTZFc1elUyTnlaV1Z1YzJoaGNtVkdjbTl0VDI1bFZHRmlWRzlCYm05MGFHVnkMCxITTWFzdGVyRmxha2VBbmFseXNpcxgBDA

If the culprit above is wrong, please file a bug using this link and hit submit:
https://bugs.chromium.org/p/chromium/issues/entry?status=Unconfirmed&labels=Pri-1,Test-Findit-Wrong&components=Tools%3ETest%3EFindit%3EFlakiness&summary=%5BFindit%5D%20Flake%20Analyzer%20-%20Wrong%20result%20for%20WebRtcDesktopCaptureBrowserTest.RunsScreenshareFromOneTabToAnother&comment=Link%20to%20Analysis%3A%20https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVywgELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCKLAWNocm9taXVtLmxpbnV4L0xpbnV4IFRlc3RzLzcxMzQ0L3Zpel9icm93c2VyX3Rlc3RzL1YyVmlVblJqUkdWemEzUnZjRU5oY0hSMWNtVkNjbTkzYzJWeVZHVnpkQzVTZFc1elUyTnlaV1Z1YzJoaGNtVkdjbTl0VDI1bFZHRmlWRzlCYm05MGFHVnkMCxITTWFzdGVyRmxha2VBbmFseXNpcxgBDA

Automatically posted by the findit-for-me app (https://goo.gl/Ot9f7N).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2fd3efecf7240ef64aec96015ec4052b275e49ab

commit 2fd3efecf7240ef64aec96015ec4052b275e49ab
Author: Yoichi Osato <yoichio@chromium.org>
Date: Fri Jul 27 07:18:25 2018

Revert "[NTP] Add ability to add/delete/reset custom links from the New Tab Page"

This reverts commit c7c6a230da8a075b37f7306f4f8902e7a3f3b490.

Reason for revert: Findit identified the culprit r578404 with confidence 70.0% in the config "chromium.linux / Linux Tests"
based on the flakiness trend:

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVywgELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCKLAWNocm9taXVtLmxpbnV4L0xpbnV4IFRlc3RzLzcxMzQ0L3Zpel9icm93c2VyX3Rlc3RzL1YyVmlVblJqUkdWemEzUnZjRU5oY0hSMWNtVkNjbTkzYzJWeVZHVnpkQzVTZFc1elUyTnlaV1Z1YzJoaGNtVkdjbTl0VDI1bFZHRmlWRzlCYm05MGFHVnkMCxITTWFzdGVyRmxha2VBbmFseXNpcxgBDA

Original change's description:
> [NTP] Add ability to add/delete/reset custom links from the New Tab Page
> 
> Added functionality for adding/removing links and restoring the Most
> Visited tiles. If the URL is not valid, the link will not be added. The
> blacklist button now opens the edit dialog (editing links is currently
> not functional and will be added in a later CL).
> 
> Also added hover/pressed/focus styling to the input fields and the
> buttons.
> 
> Design Doc: go/chrome-ntp-custom-links
> 
> Video: https://screencast.googleplex.com/cast/NTQyNDU2OTc1ODI1MzA1NnwwMjFkODAwYi1kMg
> 
> Bug: 851293
> Change-Id: Ic92e46ba93a4abcb375467a1d047cbb573f231ba
> Reviewed-on: https://chromium-review.googlesource.com/1149458
> Commit-Queue: Kristi Park <kristipark@chromium.org>
> Reviewed-by: Marc Treib <treib@chromium.org>
> Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
> Reviewed-by: Mathieu Perreault <mathp@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#578404}

TBR=bauerb@chromium.org,mathp@chromium.org,treib@chromium.org,kristipark@chromium.org

Change-Id: Ibd93fac9b68c14b68c4dd26a174818bb10b1a719
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 851293,  868237 
Reviewed-on: https://chromium-review.googlesource.com/1152594
Reviewed-by: Yoichi Osato <yoichio@chromium.org>
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578558}
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/browser_resources.grd
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/resources/local_ntp/custom_backgrounds.css
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/resources/local_ntp/custom_backgrounds.js
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/resources/local_ntp/custom_links_edit.css
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/resources/local_ntp/custom_links_edit.html
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/resources/local_ntp/custom_links_edit.js
[delete] https://crrev.com/ee3b12babcf98ab2020c827de2fb1e313e0102e5/chrome/browser/resources/local_ntp/icons/edit_menu.svg
[delete] https://crrev.com/ee3b12babcf98ab2020c827de2fb1e313e0102e5/chrome/browser/resources/local_ntp/icons/link_gray.svg
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/resources/local_ntp/local_ntp.html
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/resources/local_ntp/local_ntp.js
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/resources/local_ntp/most_visited_single.css
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/resources/local_ntp/most_visited_single.js
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/search/instant_service.cc
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/search/instant_service.h
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/search/local_ntp_source.cc
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/browser/search/most_visited_iframe_source.cc
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/chrome/renderer/searchbox/searchbox_extension.cc
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/components/ntp_tiles/most_visited_sites.cc
[modify] https://crrev.com/2fd3efecf7240ef64aec96015ec4052b275e49ab/components/ntp_tiles/most_visited_sites_unittest.cc

Test doesn't seem to be flaky anymore post-revert, though hard to tell from dashboard. Marking fixed, tenatively.