The problems in more details is:
 - you see your 10 suggestions and press [More];
 - RemoteSuggestionsProvider fetches 10 more suggestions, passes them directly to the UI and stores them as the current set in ContentSuggestionsService;
 - you scroll down to see the new suggestions (you see favicons), the previous suggestions get out of sight;
 - you scroll back to see the previous suggestions - you see no favicons.

The problem is that ContentSuggestionsService does not know about the old suggestions at that moment, it is only the RemoteSuggestionsProvider (that has them in its archive).

Have you considered passing the favicon URLs to the UI?
I do not understand why UI should ask the service for a favicon URL on each redraw.

Keeping in mind that we do not update old open NTPs, storing all shown in UI suggestions in the service looks extremely tricky. Then on each "Fetch more", we will have to find out which suggestions are actually shown on the current NTP.

Note that this issue will likely go away in ~M61.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8083bc5ed7a1989652884bec28bf775dd198b447

commit 8083bc5ed7a1989652884bec28bf775dd198b447
Author: jkrcal <jkrcal@chromium.org>
Date: Mon Apr 24 16:34:02 2017

[Remote suggestions] Get favicon URLs from archive

Fetching favicons via content suggestions service is currently only
enabled for remote suggestions. The general API for getting the URL is
via content_suggestion.h which does not work for archived suggestions
(i.e. by Fetch More).

This CL introduces a quick fix to loop in remote suggestions provider
for the favicon URLs of suggestions not known to
ContentSuggestionsService. A cleaner fix requires more thinking /
refactoring.

This is a M59 merge candidate.

BUG= 714025 

Review-Url: https://codereview.chromium.org/2829963005
Cr-Commit-Position: refs/heads/master@{#466653}

[modify] https://crrev.com/8083bc5ed7a1989652884bec28bf775dd198b447/components/ntp_snippets/content_suggestion.cc
[modify] https://crrev.com/8083bc5ed7a1989652884bec28bf775dd198b447/components/ntp_snippets/content_suggestion.h
[modify] https://crrev.com/8083bc5ed7a1989652884bec28bf775dd198b447/components/ntp_snippets/content_suggestions_service.cc
[modify] https://crrev.com/8083bc5ed7a1989652884bec28bf775dd198b447/components/ntp_snippets/content_suggestions_service.h
[modify] https://crrev.com/8083bc5ed7a1989652884bec28bf775dd198b447/components/ntp_snippets/remote/remote_suggestions_provider.h
[modify] https://crrev.com/8083bc5ed7a1989652884bec28bf775dd198b447/components/ntp_snippets/remote/remote_suggestions_provider_impl.cc
[modify] https://crrev.com/8083bc5ed7a1989652884bec28bf775dd198b447/components/ntp_snippets/remote/remote_suggestions_provider_impl.h
[modify] https://crrev.com/8083bc5ed7a1989652884bec28bf775dd198b447/components/ntp_snippets/remote/remote_suggestions_scheduler_impl_unittest.cc

A simple CL that unblocks an experiment on the New Ta Page.

Verified on Canary 60.0.3080.0.

Your change meets the bar and is auto-approved for M59. Please go ahead and merge the CL to branch 3071 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), gkihumba@(ChromeOS), Abdul Syed@(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/+/0a1c2e959fc5b622ce4b82239c4afa5a56404d0b

commit 0a1c2e959fc5b622ce4b82239c4afa5a56404d0b
Author: Jan Krcal <jkrcal@chromium.org>
Date: Wed Apr 26 07:51:00 2017

[Remote suggestions] Get favicon URLs from archive

Fetching favicons via content suggestions service is currently only
enabled for remote suggestions. The general API for getting the URL is
via content_suggestion.h which does not work for archived suggestions
(i.e. by Fetch More).

This CL introduces a quick fix to loop in remote suggestions provider
for the favicon URLs of suggestions not known to
ContentSuggestionsService. A cleaner fix requires more thinking /
refactoring.

This is a M59 merge candidate.

BUG= 714025 

Review-Url: https://codereview.chromium.org/2829963005
Cr-Commit-Position: refs/heads/master@{#466653}
(cherry picked from commit 8083bc5ed7a1989652884bec28bf775dd198b447)

Review-Url: https://codereview.chromium.org/2846503002 .
Cr-Commit-Position: refs/branch-heads/3071@{#219}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}

[modify] https://crrev.com/0a1c2e959fc5b622ce4b82239c4afa5a56404d0b/components/ntp_snippets/content_suggestion.cc
[modify] https://crrev.com/0a1c2e959fc5b622ce4b82239c4afa5a56404d0b/components/ntp_snippets/content_suggestion.h
[modify] https://crrev.com/0a1c2e959fc5b622ce4b82239c4afa5a56404d0b/components/ntp_snippets/content_suggestions_service.cc
[modify] https://crrev.com/0a1c2e959fc5b622ce4b82239c4afa5a56404d0b/components/ntp_snippets/content_suggestions_service.h
[modify] https://crrev.com/0a1c2e959fc5b622ce4b82239c4afa5a56404d0b/components/ntp_snippets/remote/remote_suggestions_provider.h
[modify] https://crrev.com/0a1c2e959fc5b622ce4b82239c4afa5a56404d0b/components/ntp_snippets/remote/remote_suggestions_provider_impl.cc
[modify] https://crrev.com/0a1c2e959fc5b622ce4b82239c4afa5a56404d0b/components/ntp_snippets/remote/remote_suggestions_provider_impl.h
[modify] https://crrev.com/0a1c2e959fc5b622ce4b82239c4afa5a56404d0b/components/ntp_snippets/remote/remote_suggestions_scheduler_impl_unittest.cc