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}
19 files changed