Fix crash when deleting ReadingListStore via ReadingListModelStorage*.

ReadingListStore inherits from multiple classes, including from
ReadingListModelStorage that does not define a virtual destructor.

Since ReadingListModelImpl has a scoped_ptr to ReadingListModelStorage,
it calls the base destructor with a pointer that does not correspond
to memory returned by "new" (it points to somewhere inside the memory
block).

The issue can be fixed by defining a virtual destructor on the base
class ReadingListModelStorage (as all class with virtual method should
do). Also mark the class a non-copyable since copying would cause slicing.

BUG=673169

Review-Url: https://codereview.chromium.org/2563303002
Cr-Commit-Position: refs/heads/master@{#437800}

components/reading_list/ios/reading_list_model_storage.h

@@ -7,6 +7,7 @@
 
 #include <vector>
 
+#include "base/macros.h"
 #include "components/reading_list/ios/reading_list_entry.h"
 
 class ReadingListModel;
@@ -22,6 +23,9 @@ 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,
@@ -48,8 +52,15 @@ class ReadingListModelStorage {
 
   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_