[Sync] Initial implementation of foreign sessions suggestions provider.

components/ntp_snippets/category.h

 // 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.
 
 #ifndef COMPONENTS_NTP_SNIPPETS_CATEGORY_H_
 #define COMPONENTS_NTP_SNIPPETS_CATEGORY_H_
 
 #include <ostream>
 
 namespace ntp_snippets {
@@ skipping 13 matching lines @@
 
   // Pages downloaded by the user for offline consumption.
   DOWNLOADS,
 
   // Recently used bookmarks.
   BOOKMARKS,
 
   // Physical Web page available in the vicinity.
   PHYSICAL_WEB_PAGES,
 
+  // Pages recently browsed to on other devices.
+  FOREIGN_TABS,
+
   // Follows the last local category.
   LOCAL_CATEGORIES_COUNT,
 
   // Remote categories come after this.
   REMOTE_CATEGORIES_OFFSET = 10000,
 
   // Articles for you.
   ARTICLES,
 };
 
@@ skipping 31 matching lines @@
 
 struct Category::CompareByID {
   bool operator()(const Category& left, const Category& right) const;
 };
 
 std::ostream& operator<<(std::ostream& os, const Category& obj);
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_CATEGORY_H_