Add methods to Reading List Model

ios/chrome/browser/reading_list/reading_list_model_impl.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_IMPL_H_
 #define IOS_CHROME_BROWSER_READING_LIST_READING_LIST_MODEL_IMPL_H_
 
 #include <memory>
 
 #include "components/keyed_service/core/keyed_service.h"
@@ skipping 31 matching lines @@
   bool CallbackEntryURL(
       const GURL& url,
       base::Callback<void(const ReadingListEntry&)> callback) const override;
 
   void RemoveEntryByUrl(const GURL& url) override;
 
   const ReadingListEntry& AddEntry(const GURL& url,
                                    const std::string& title) override;
 
   void MarkReadByURL(const GURL& url) override;
+  void MarkUnreadByURL(const GURL& url) override;
 
   void SetEntryTitle(const GURL& url, const std::string& title) override;
   void SetEntryDistilledURL(const GURL& url,
                             const GURL& distilled_url) override;
   void SetEntryDistilledState(
       const GURL& url,
       ReadingListEntry::DistillationState state) override;
 
  protected:
   void EndBatchUpdates() override;
 
  private:
   typedef std::vector<ReadingListEntry> ReadingListEntries;
 
   ReadingListEntries unread_;
   ReadingListEntries read_;
   std::unique_ptr<ReadingListModelStorage> storageLayer_;
   bool hasUnseen_;
   bool loaded_;
 
   DISALLOW_COPY_AND_ASSIGN(ReadingListModelImpl);
 };
 
 #endif  // IOS_CHROME_BROWSER_READING_LIST_READING_LIST_MODEL_MEMORY_H_