Add methods to Reading List Model

ios/chrome/browser/reading_list/reading_list_model.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 IOS_CHROME_BROWSER_READING_LIST_READING_LIST_MODEL_H_
 #define IOS_CHROME_BROWSER_READING_LIST_READING_LIST_MODEL_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 61 matching lines @@
                                            const std::string& title) = 0;
 
   // Removes an entry. The removal may be asynchronous, and not happen
   // immediately.
   virtual void RemoveEntryByUrl(const GURL& url) = 0;
 
   // If the |url| is in the reading list and unread, mark it read. If it is in
   // the reading list and read, move it to the top of unread if it is not here
   // already. This may trigger deletion of old read entries.
   virtual void MarkReadByURL(const GURL& url) = 0;
+  // If the |url| is in the reading list and read, mark it unread. If it is in
+  // the reading list and unread, move it to the top of read if it is not here
+  // already.
+  virtual void MarkUnreadByURL(const GURL& url) = 0;
 
   // Methods to mutate an entry. Will locate the relevant entry by URL. Does
   // nothing if the entry is not found.
   virtual void SetEntryTitle(const GURL& url, const std::string& title) = 0;
   virtual void SetEntryDistilledURL(const GURL& url,
                                     const GURL& distilled_url) = 0;
   virtual void SetEntryDistilledState(
       const GURL& url,
       ReadingListEntry::DistillationState state) = 0;
 
@@ skipping 27 matching lines @@
   // ReadingListBatchUpdateToken dtor.
   virtual void EndBatchUpdates();
 
  private:
   unsigned int current_batch_updates_count_;
 
   DISALLOW_COPY_AND_ASSIGN(ReadingListModel);
 };
 
 #endif  // IOS_CHROME_BROWSER_READING_LIST_READING_LIST_MODEL_H_