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

components/ntp_snippets/sessions/foreign_sessions_suggestions_provider.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/sessions/foreign_sessions_suggestions_provider.h"
 
 #include <algorithm>
 #include <map>
 #include <tuple>
 #include <utility>
@@ skipping 99 matching lines @@
 
 CategoryStatus ForeignSessionsSuggestionsProvider::GetCategoryStatus(
     Category category) {
   DCHECK_EQ(category, provided_category_);
   return category_status_;
 }
 
 CategoryInfo ForeignSessionsSuggestionsProvider::GetCategoryInfo(
     Category category) {
   DCHECK_EQ(category, provided_category_);
-  return CategoryInfo(l10n_util::GetStringUTF16(
-                          IDS_NTP_FOREIGN_SESSIONS_SUGGESTIONS_SECTION_HEADER),
-                      ContentSuggestionsCardLayout::MINIMAL_CARD,
-                      /*has_more_button=*/true,
-                      /*show_if_empty=*/false);
+  return CategoryInfo(
+      l10n_util::GetStringUTF16(
+          IDS_NTP_FOREIGN_SESSIONS_SUGGESTIONS_SECTION_HEADER),
+      ContentSuggestionsCardLayout::MINIMAL_CARD,
+      /*has_more_button=*/true,
+      /*show_if_empty=*/false,
+      l10n_util::GetStringUTF16(IDS_NTP_SUGGESTIONS_SECTION_EMPTY));
+  // TODO(skym): Replace IDS_NTP_SUGGESTIONS_SECTION_EMPTY with a
+  // category-specific string.
 }
 
 void ForeignSessionsSuggestionsProvider::DismissSuggestion(
     const ContentSuggestion::ID& suggestion_id) {
   // TODO(skym): Right now this continuously grows, without clearing out old and
   // irrelevant entries. Could either use a timestamp and expire after a
   // threshold, or compare with current foreign tabs and remove anything that
   // isn't actively blockign a foreign_sessions tab.
   std::set<std::string> dismissed_ids = prefs::ReadDismissedIDsFromPrefs(
       *pref_service_, prefs::kDismissedForeignSessionsSuggestions);
@@ skipping 170 matching lines @@
   // This field is sandwiched between the url's favicon, which is on the left,
   // and the |publish_date|, which is to the right. The domain should always
   // appear next to the favicon.
   suggestion.set_publisher_name(
       base::UTF8ToUTF16(data.navigation->virtual_url().host() + " - " +
                         data.session->session_name));
   return suggestion;
 }
 
 }  // namespace ntp_snippets