Add more features to ntp-tiles-internal

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 60 matching lines @@
   DCHECK(suggestions_service_);
   if (supervisor_)
     supervisor_->SetObserver(this);
 }
 
 MostVisitedSites::~MostVisitedSites() {
   if (supervisor_)
     supervisor_->SetObserver(nullptr);
 }
 
+bool MostVisitedSites::DoesSourceExist(NTPTileSource source) const {
+  switch (source) {
+    case NTPTileSource::TOP_SITES:
+      return top_sites_ != nullptr;
+    case NTPTileSource::SUGGESTIONS_SERVICE:
+      return suggestions_service_ != nullptr;
+    case NTPTileSource::POPULAR:
+      return popular_sites_ != nullptr;
+    case NTPTileSource::WHITELIST:
+      return supervisor_ != nullptr;
+  }
+  NOTREACHED();
+  return false;
+}
+
 void MostVisitedSites::SetMostVisitedURLsObserver(Observer* observer,
                                                   int num_sites) {
   DCHECK(observer);
   observer_ = observer;
   num_sites_ = num_sites;
 
   // The order for this condition is important, ShouldShowPopularSites() should
   // always be called last to keep metrics as relevant as possible.
   if (popular_sites_ && NeedPopularSites(prefs_, num_sites_) &&
       ShouldShowPopularSites()) {
@@ skipping 328 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