provide static popular sites for first run

components/ntp_tiles/most_visited_sites.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/ntp_tiles/most_visited_sites.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 #include <utility>
@@ skipping 402 matching lines @@
 
   observer_->OnMostVisitedURLsAvailable(current_tiles_);
 }
 
 void MostVisitedSites::OnPopularSitesDownloaded(bool success) {
   if (!success) {
     LOG(WARNING) << "Download of popular sites failed";
     return;
   }
 
-  // Re-build the tile list. Once done, this will notify the observer.
-  BuildCurrentTiles();
+  // Only build the tiles if there haven't been any. Otherwise, the UI should
+  // not flicker.
+  if (current_tiles_.empty()) {

[sfiera, 2017/02/09 12:39:06]

Can this actually happen? For a new user, we should already have been able to
come up with eight tiles.

[fhorschig, 2017/02/09 15:30:18]

Removed completely. 

+    // Re-build the tile list. Once done, this will notify the observer.
+    BuildCurrentTiles();
+  }
 }
 
 void MostVisitedSites::OnIconMadeAvailable(const GURL& site_url,
                                            bool newly_available) {
   if (newly_available)
     observer_->OnIconMadeAvailable(site_url);
 }
 
 void MostVisitedSites::TopSitesLoaded(TopSites* top_sites) {}
 
 void MostVisitedSites::TopSitesChanged(TopSites* top_sites,
                                        ChangeReason change_reason) {
   if (mv_source_ == NTPTileSource::TOP_SITES) {
     // The displayed tiles are invalidated.
     InitiateTopSitesQuery();
   }
 }
 
 }  // namespace ntp_tiles