[NTP Snippets] Pass "no suggestions" message from the backend to the UI

components/ntp_snippets/content_suggestions_service_unittest.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 <memory>
 #include <utility>
 #include <vector>
 
@@ skipping 42 matching lines @@
       statuses_[category.id()] = CategoryStatus::AVAILABLE;
     }
   }
 
   CategoryStatus GetCategoryStatus(Category category) override {
     return statuses_[category.id()];
   }
 
   CategoryInfo GetCategoryInfo(Category category) override {
     return CategoryInfo(base::ASCIIToUTF16("Section title"),
-                        ContentSuggestionsCardLayout::FULL_CARD, true, true);
+                        ContentSuggestionsCardLayout::FULL_CARD, true, true,
+                        base::ASCIIToUTF16("No suggestions message"));
   }
 
   void FireSuggestionsChanged(
       Category category,
       std::vector<ContentSuggestion> suggestions) {
     observer()->OnNewSuggestions(this, category, std::move(suggestions));
   }
 
   void FireCategoryStatusChanged(Category category, CategoryStatus new_status) {
     statuses_[category.id()] = new_status;
@@ skipping 608 matching lines @@
   provider = RegisterProvider(category);
   provider->FireCategoryStatusChangedWithCurrentStatus(category);
   EXPECT_TRUE(service()->IsCategoryDismissed(category));
 
   service()->RestoreDismissedCategories();
   EXPECT_FALSE(service()->IsCategoryDismissed(category));
   EXPECT_THAT(providers().find(category)->second, Eq(provider));
 }
 
 }  // namespace ntp_snippets