Fix crash when deleting ReadingListStore via ReadingListModelStorage*.

components/reading_list/ios/reading_list_model_storage.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_IOS_READING_LIST_MODEL_STORAGE_H_
 #define COMPONENTS_READING_LIST_IOS_READING_LIST_MODEL_STORAGE_H_
 
 #include <vector>
 
+#include "base/macros.h"
 #include "components/reading_list/ios/reading_list_entry.h"
 
 class ReadingListModel;
 class ReadingListStoreDelegate;
 
 namespace syncer {
 class ModelTypeSyncBridge;
 }
 
 // Interface for a persistence layer for reading list.
 // All interface methods have to be called on main thread.
 class ReadingListModelStorage {
  public:
   class ScopedBatchUpdate;
 
+  ReadingListModelStorage() {}
+  virtual ~ReadingListModelStorage() {}
+
   // Sets the model the Storage is backing.
   // This will trigger store initalization and load persistent entries.
   virtual void SetReadingListModel(ReadingListModel* model,
                                    ReadingListStoreDelegate* delegate) = 0;
 
   // Returns the class responsible for handling sync messages.
   virtual syncer::ModelTypeSyncBridge* GetModelTypeSyncBridge() = 0;
 
   // Starts a transaction. All Save/Remove entry will be delayed until the
   // transaction is commited.
   // Multiple transaction can be started at the same time. Commit will happen
   // when the last transaction is commited.
   // Returns a scoped batch update object that should be retained while the
   // batch update is performed. Deallocating this object will inform model that
   // the batch update has completed.
   virtual std::unique_ptr<ScopedBatchUpdate> EnsureBatchCreated() = 0;
 
   // Saves or updates an entry. If the entry is not yet in the database, it is
   // created.
   virtual void SaveEntry(const ReadingListEntry& entry) = 0;
 
   // Removed an entry from the storage.
   virtual void RemoveEntry(const ReadingListEntry& entry) = 0;
 
   class ScopedBatchUpdate {
    public:
+    ScopedBatchUpdate() {}
     virtual ~ScopedBatchUpdate() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(ScopedBatchUpdate);
   };
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ReadingListModelStorage);
 };
 
 #endif  // COMPONENTS_READING_LIST_IOS_READING_LIST_MODEL_STORAGE_H_