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 48 matching lines @@
 }
 
 const std::vector<ContentSuggestion>&
 ContentSuggestionsService::GetSuggestionsForCategory(Category category) const {
   auto iterator = suggestions_by_category_.find(category);
   if (iterator == suggestions_by_category_.end())
     return no_suggestions_;
   return iterator->second;
 }
 
+void ContentSuggestionsService::FetchMoreSuggestions(Category category) {
+  auto iterator = providers_by_category_.find(category);
+  if (iterator != providers_by_category_.end())
+    iterator->second->FetchMoreSuggestions(category);
+}
+
 void ContentSuggestionsService::FetchSuggestionImage(
     const std::string& suggestion_id,
     const ImageFetchedCallback& callback) {
   if (!id_category_map_.count(suggestion_id)) {
     LOG(WARNING) << "Requested image for unknown suggestion " << suggestion_id;
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE, base::Bind(callback, suggestion_id, gfx::Image()));
     return;
   }
   Category category = id_category_map_.at(suggestion_id);
@@ skipping 169 matching lines @@
   return true;
 }
 
 void ContentSuggestionsService::NotifyCategoryStatusChanged(Category category) {
   FOR_EACH_OBSERVER(
       Observer, observers_,
       OnCategoryStatusChanged(category, GetCategoryStatus(category)));
 }
 
 }  // namespace ntp_snippets