Enable RL sync by default on iOS

components/reading_list/reading_list_store_delegate.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_READING_LIST_READING_LIST_STORE_DELEGATE_H_
-#define COMPONENTS_READING_LIST_READING_LIST_STORE_DELEGATE_H_
-
-class ReadingListEntry;
-
-// The delegate to handle callbacks from the ReadingListStore.
-class ReadingListStoreDelegate {
- public:
-  // These three mathods handle callbacks from a ReadingListStore.
-  virtual void StoreLoaded(std::unique_ptr<ReadingListEntries> unread,
-                           std::unique_ptr<ReadingListEntries> read) = 0;
-  // Handle sync events.
-  // Called to add a new entry to the model.
-  // |entry| must not already exist in the model.
-  virtual void SyncAddEntry(std::unique_ptr<ReadingListEntry> entry,
-                            bool read) = 0;
-
-  // Called to merge a sync entry with a local entry in the model.
-  // A local entry with the same URL must exist in the local store and have an
-  // older UpdateTime.
-  // Return a pointer to the merged entry.
-  virtual ReadingListEntry* SyncMergeEntry(
-      std::unique_ptr<ReadingListEntry> entry,
-      bool read) = 0;
-
-  // Called to remove an entry to the model.
-  virtual void SyncRemoveEntry(const GURL& url) = 0;
-};
-
-#endif  // COMPONENTS_READING_LIST_READING_LIST_STORE_DELEGATE_H_