The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/648408687025e4e954a392135c93e80a43481b10

commit 648408687025e4e954a392135c93e80a43481b10
Author: mastiz <mastiz@chromium.org>
Date: Thu Jan 05 12:42:31 2017

ntp_tiles: Fix Top Sites potentially overriding Suggestions Service

The current implementation of MostVisitedSites has a race condition
which can cause Top Sites tiles to be shown in the NTP although
Suggestions Service results are available.

As reflected in updated tests, this is the case when Top Sites takes
longer to respond than the Suggestions Service, but only if no cached
tiles exist for the Suggestions Service.

BUG= 674909 

Review-Url: https://codereview.chromium.org/2584853002
Cr-Commit-Position: refs/heads/master@{#441632}

[modify] https://crrev.com/648408687025e4e954a392135c93e80a43481b10/components/ntp_tiles/most_visited_sites.cc
[modify] https://crrev.com/648408687025e4e954a392135c93e80a43481b10/components/ntp_tiles/most_visited_sites_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d0da75e5f451ce330c3cc3c1448c624a88e5af1b

commit d0da75e5f451ce330c3cc3c1448c624a88e5af1b
Author: mastiz <mastiz@chromium.org>
Date: Mon Jan 09 11:36:48 2017

ntp_tiles: Avoid redundant calls to TopSites

The redundant calls cause propagating redundant updates to client
observers, as reflected by tests. This should be harmless, but let's
avoid possible UI flickering.

BUG= 674909 

Review-Url: https://codereview.chromium.org/2577253003
Cr-Commit-Position: refs/heads/master@{#442234}

[modify] https://crrev.com/d0da75e5f451ce330c3cc3c1448c624a88e5af1b/components/ntp_tiles/most_visited_sites.cc
[modify] https://crrev.com/d0da75e5f451ce330c3cc3c1448c624a88e5af1b/components/ntp_tiles/most_visited_sites.h
[modify] https://crrev.com/d0da75e5f451ce330c3cc3c1448c624a88e5af1b/components/ntp_tiles/most_visited_sites_unittest.cc