Fix popular sites missing refreshes

We count baked-in popular sites to personal sites when deciding
whether to refetch the current set of popular sites.
This causes popular sites to not refresh if the first fetch failed.

With this CL, we treat baked-in popular sites as popular sites which
brings back timely refreshes.

Bug: 803773
Change-Id: I96c34f02f440d453eb1ae3b422c422c4827b0127
Reviewed-on: https://chromium-review.googlesource.com/878322
Commit-Queue: Friedrich Horschig <[email protected]>
Reviewed-by: Marc Treib <[email protected]>
Cr-Original-Commit-Position: refs/heads/master@{#530857}(cherry picked from commit 764f290)
Reviewed-on: https://chromium-review.googlesource.com/883441
Reviewed-by: Friedrich Horschig <[email protected]>
Cr-Commit-Position: refs/branch-heads/3325@{#58}
Cr-Branched-From: bc084a8-refs/heads/master@{#530369}

components/ntp_tiles/most_visited_sites.cc

@@ -563,8 +563,10 @@ void MostVisitedSites::SaveTilesAndNotify(NTPTilesVector personal_tiles) {
 
   int num_personal_tiles = 0;
   for (const auto& tile : *current_tiles_) {
-    if (tile.source != TileSource::POPULAR)
+    if (tile.source != TileSource::POPULAR &&
+        tile.source != TileSource::POPULAR_BAKED_IN) {
       num_personal_tiles++;
+    }
   }
   prefs_->SetInteger(prefs::kNumPersonalTiles, num_personal_tiles);
   if (!observer_)