[NTP Snippets] Properly restore the status of restored sections

components/ntp_snippets/content_suggestions_service.cc

 // Copyright 2016 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_snippets/content_suggestions_service.h"
 
 #include <algorithm>
 #include <iterator>
 #include <set>
 #include <utility>
@@ skipping 174 matching lines @@
 ////////////////////////////////////////////////////////////////////////////////
 // Private methods
 
 void ContentSuggestionsService::OnNewSuggestions(
     ContentSuggestionsProvider* provider,
     Category category,
     std::vector<ContentSuggestion> suggestions) {
   if (RegisterCategoryIfRequired(provider, category))
     NotifyCategoryStatusChanged(category);
 
-  if (!IsCategoryStatusAvailable(provider->GetCategoryStatus(category)))
+  if (!IsCategoryStatusAvailable(provider->GetCategoryStatus(category))) {
+    // A provider shouldn't send us suggestions while it's not available.
+    DCHECK(suggestions.empty());
     return;
+  }
 
   suggestions_by_category_[category] = std::move(suggestions);
 
   // The positioning of the bookmarks category depends on whether it's empty.
   // TODO(treib): Remove this temporary hack, crbug.com/640568.
   if (category.IsKnownCategory(KnownCategories::BOOKMARKS))
     SortCategories();
 
   FOR_EACH_OBSERVER(Observer, observers_, OnNewSuggestions(category));
 }
@@ skipping 137 matching lines @@
           if (left.IsKnownCategory(KnownCategories::BOOKMARKS))
             return false;
           if (right.IsKnownCategory(KnownCategories::BOOKMARKS))
             return true;
         }
         return category_factory_.CompareCategories(left, right);
       });
 }
 
 }  // namespace ntp_snippets