Support action button to fetch more content suggestions

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 "base/bind.h"
@@ skipping 165 matching lines @@
   providers_.push_back(std::move(provider));
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Private methods
 
 void ContentSuggestionsService::OnNewSuggestions(
     ContentSuggestionsProvider* provider,
     Category category,
     std::vector<ContentSuggestion> new_suggestions) {
-  if (RegisterCategoryIfRequired(provider, category)) {
+  if (RegisterCategoryIfRequired(provider, category))
     NotifyCategoryStatusChanged(category);
-  }
+
+  if (!IsCategoryStatusAvailable(provider->GetCategoryStatus(category)))
+    return;
 
   for (const ContentSuggestion& suggestion :
        suggestions_by_category_[category]) {
     id_category_map_.erase(suggestion.id());
   }
 
-  for (const ContentSuggestion& suggestion : new_suggestions) {
+  for (const ContentSuggestion& suggestion : new_suggestions)
     id_category_map_.insert(std::make_pair(suggestion.id(), category));
-  }
 
   suggestions_by_category_[category] = std::move(new_suggestions);
 
   FOR_EACH_OBSERVER(Observer, observers_, OnNewSuggestions(category));
 }
 
 void ContentSuggestionsService::OnCategoryStatusChanged(
     ContentSuggestionsProvider* provider,
     Category category,
     CategoryStatus new_status) {
@@ skipping 40 matching lines @@
   return true;
 }
 
 void ContentSuggestionsService::NotifyCategoryStatusChanged(Category category) {
   FOR_EACH_OBSERVER(
       Observer, observers_,
       OnCategoryStatusChanged(category, GetCategoryStatus(category)));
 }
 
 }  // namespace ntp_snippets