[SuggestionsService] Split SuggestionsService interface from impl

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 143 matching lines @@
 // static
 void MostVisitedSites::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   registry->RegisterIntegerPref(prefs::kNumPersonalTiles, 0);
 }
 
 void MostVisitedSites::BuildCurrentTiles() {
   // Get the current suggestions from cache. If the cache is empty, this will
   // fall back to TopSites.
   OnSuggestionsProfileAvailable(
-      suggestions_service_->GetSuggestionsDataFromCache());
+      suggestions_service_->GetSuggestionsDataFromCache().value_or(
+          SuggestionsProfile()));
 }
 
 void MostVisitedSites::InitiateTopSitesQuery() {
   if (!top_sites_)
     return;
   top_sites_->GetMostVisitedURLs(
       base::Bind(&MostVisitedSites::OnMostVisitedURLsAvailable,
                  weak_ptr_factory_.GetWeakPtr()),
       false);
 }
@@ skipping 225 matching lines @@
 
 void MostVisitedSites::TopSitesChanged(TopSites* top_sites,
                                        ChangeReason change_reason) {
   if (mv_source_ == NTPTileSource::TOP_SITES) {
     // The displayed tiles are invalidated.
     InitiateTopSitesQuery();
   }
 }
 
 }  // namespace ntp_tiles