[Sync] Fix behavior when there are two type roots for a type

sync/syncable/parent_child_index.h

 // Copyright (c) 2012 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 SYNC_SYNCABLE_PARENT_CHILD_INDEX_H_
 #define SYNC_SYNCABLE_PARENT_CHILD_INDEX_H_
 
 #include <map>
+#include <memory>
 #include <set>
 #include <vector>
 
 #include "base/macros.h"
-#include "base/memory/scoped_vector.h"
 #include "sync/base/sync_export.h"
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/syncable/syncable_id.h"
 
 namespace syncer {
 namespace syncable {
 
 struct EntryKernel;
 class ParentChildIndex;
 
 // A node ordering function.
 struct SYNC_EXPORT ChildComparator {
   bool operator() (const EntryKernel* a, const EntryKernel* b) const;
 };
 
 // An ordered set of nodes.
 typedef std::set<EntryKernel*, ChildComparator> OrderedChildSet;
+typedef std::shared_ptr<OrderedChildSet> OrderedChildSetRef;
 
 // Container that tracks parent-child relationships.
 // Provides fast lookup of all items under a given parent.
 class SYNC_EXPORT ParentChildIndex {
  public:
   ParentChildIndex();
   ~ParentChildIndex();
 
   // Returns whether or not this entry belongs in the index.
   // True for all non-deleted, non-root entries.
@@ skipping 15 matching lines @@
   // Returns all children of the entry.  Returns NULL if the node has no
   // children.
   const OrderedChildSet* GetChildren(EntryKernel* e) const;
 
   // Returns all siblings of the entry.
   const OrderedChildSet* GetSiblings(EntryKernel* e) const;
 
  private:
   friend class ParentChildIndexTest;
 
-  typedef std::map<Id, OrderedChildSet*> ParentChildrenMap;
+  typedef std::map<Id, OrderedChildSetRef> ParentChildrenMap;
   typedef std::vector<Id> TypeRootIds;
-  typedef ScopedVector<OrderedChildSet> TypeRootChildSets;
+  typedef std::vector<OrderedChildSetRef> TypeRootChildSets;
 
   static bool ShouldUseParentId(const Id& parent_id, ModelType model_type);
 
   // Returns OrderedChildSet that should contain the specified entry
   // based on the entry's Parent ID or model type.
-  const OrderedChildSet* GetChildSet(EntryKernel* e) const;
+  const OrderedChildSetRef GetChildSet(EntryKernel* e) const;
 
   // Returns OrderedChildSet that contain entries of the |model_type| type.
-  const OrderedChildSet* GetModelTypeChildSet(ModelType model_type) const;
+  const OrderedChildSetRef GetModelTypeChildSet(ModelType model_type) const;
 
   // Returns mutable OrderedChildSet that contain entries of the |model_type|
   // type. Create one as necessary.
-  OrderedChildSet* GetOrCreateModelTypeChildSet(ModelType model_type);
+  OrderedChildSetRef GetOrCreateModelTypeChildSet(ModelType model_type);
 
   // Returns previously cached model type root ID for the given |model_type|.
   const Id& GetModelTypeRootId(ModelType model_type) const;
 
   // A map of parent IDs to children.
   // Parents with no children are not included in this map.
   ParentChildrenMap parent_children_map_;
 
   // This array tracks model type roots IDs.
   TypeRootIds model_type_root_ids_;
 
   // This array contains pre-defined child sets for
   // non-hierarchical types (types with flat hierarchy) that support entries
   // with implicit parent.
   TypeRootChildSets type_root_child_sets_;
 
   DISALLOW_COPY_AND_ASSIGN(ParentChildIndex);
 };
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // SYNC_SYNCABLE_PARENT_CHILD_INDEX_H_