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diff --git a/content/browser/indexed_db/leveldb/leveldb_transaction.h b/content/browser/indexed_db/leveldb/leveldb_transaction.h
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+++ b/content/browser/indexed_db/leveldb/leveldb_transaction.h
@@ -0,0 +1,179 @@
+// Copyright (c) 2013 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 CONTENT_BROWSER_INDEXED_DB_LEVELDB_LEVELDB_TRANSACTION_H_
+#define CONTENT_BROWSER_INDEXED_DB_LEVELDB_LEVELDB_TRANSACTION_H_
+
+#include <set>
+#include <vector>
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/browser/indexed_db/leveldb/avltree.h"
+#include "content/browser/indexed_db/leveldb/leveldb_comparator.h"
+#include "content/browser/indexed_db/leveldb/leveldb_database.h"
+#include "content/browser/indexed_db/leveldb/leveldb_iterator.h"
+#include "content/browser/indexed_db/leveldb/leveldb_slice.h"
+
+namespace content {
+
+class LevelDBWriteBatch;
+
+class CONTENT_EXPORT LevelDBTransaction
+    : public base::RefCounted<LevelDBTransaction> {
+ public:
+  static scoped_refptr<LevelDBTransaction> Create(LevelDBDatabase* db);
+
+  void Put(const LevelDBSlice& key, const std::vector<char>& value);
+  void Remove(const LevelDBSlice& key);
+  bool Get(const LevelDBSlice& key, std::vector<char>& value, bool& found);
+  bool Commit();
+  void Rollback();
+
+  scoped_ptr<LevelDBIterator> CreateIterator();
+
+ private:
+  LevelDBTransaction(LevelDBDatabase* db);
+  virtual ~LevelDBTransaction();
+  friend class base::RefCounted<LevelDBTransaction>;
+
+  struct AVLTreeNode {
+    AVLTreeNode();
+    ~AVLTreeNode();
+    std::vector<char> key;
+    std::vector<char> value;
+    bool deleted;
+
+    AVLTreeNode* less;
+    AVLTreeNode* greater;
+    int balance_factor;
+    DISALLOW_COPY_AND_ASSIGN(AVLTreeNode);
+  };
+
+  struct AVLTreeAbstractor {
+    typedef AVLTreeNode* handle;
+    typedef size_t size;
+    typedef LevelDBSlice key;
+
+    handle get_less(handle h) { return h->less; }
+    void set_less(handle h, handle less) { h->less = less; }
+    handle get_greater(handle h) { return h->greater; }
+    void set_greater(handle h, handle greater) { h->greater = greater; }
+
+    int get_balance_factor(handle h) { return h->balance_factor; }
+    void set_balance_factor(handle h, int bf) { h->balance_factor = bf; }
+
+    int compare_key_key(const key& ka, const key& kb) {
+      return comparator_->Compare(ka, kb);
+    }
+    int compare_key_node(const key& k, handle h) {
+      return compare_key_key(k, key(h->key));
+    }
+    int compare_node_node(handle ha, handle hb) {
+      return compare_key_key(key(ha->key), key(hb->key));
+    }
+
+    static handle null() { return 0; }
+
+    const LevelDBComparator* comparator_;
+  };
+
+  typedef AVLTree<AVLTreeAbstractor> TreeType;
+
+  class TreeIterator : public LevelDBIterator {
+   public:
+    static scoped_ptr<TreeIterator> Create(LevelDBTransaction* transaction);
+    virtual ~TreeIterator();
+
+    virtual bool IsValid() const OVERRIDE;
+    virtual void SeekToLast() OVERRIDE;
+    virtual void Seek(const LevelDBSlice& slice) OVERRIDE;
+    virtual void Next() OVERRIDE;
+    virtual void Prev() OVERRIDE;
+    virtual LevelDBSlice Key() const OVERRIDE;
+    virtual LevelDBSlice Value() const OVERRIDE;
+    bool IsDeleted() const;
+    void Reset();
+
+   private:
+    TreeIterator(LevelDBTransaction* transaction);
+    mutable TreeType::Iterator iterator_;  // Dereferencing this is non-const.
+    TreeType* tree_;
+    LevelDBTransaction* transaction_;
+    std::vector<char> key_;
+  };
+
+  class TransactionIterator : public LevelDBIterator {
+   public:
+    virtual ~TransactionIterator();
+    static scoped_ptr<TransactionIterator> Create(
+        scoped_refptr<LevelDBTransaction> transaction);
+
+    virtual bool IsValid() const OVERRIDE;
+    virtual void SeekToLast() OVERRIDE;
+    virtual void Seek(const LevelDBSlice& target) OVERRIDE;
+    virtual void Next() OVERRIDE;
+    virtual void Prev() OVERRIDE;
+    virtual LevelDBSlice Key() const OVERRIDE;
+    virtual LevelDBSlice Value() const OVERRIDE;
+    void TreeChanged();
+
+   private:
+    TransactionIterator(scoped_refptr<LevelDBTransaction> transaction);
+    void HandleConflictsAndDeletes();
+    void SetCurrentIteratorToSmallestKey();
+    void SetCurrentIteratorToLargestKey();
+    void RefreshTreeIterator() const;
+    bool TreeIteratorIsLower() const;
+    bool TreeIteratorIsHigher() const;
+
+    scoped_refptr<LevelDBTransaction> transaction_;
+    const LevelDBComparator* comparator_;
+    mutable scoped_ptr<TreeIterator> tree_iterator_;
+    scoped_ptr<LevelDBIterator> db_iterator_;
+    LevelDBIterator* current_;
+
+    enum Direction {
+      FORWARD,
+      REVERSE
+    };
+    Direction direction_;
+    mutable bool tree_changed_;
+  };
+
+  void Set(const LevelDBSlice& key,
+           const std::vector<char>& value,
+           bool deleted);
+  void ClearTree();
+  void RegisterIterator(TransactionIterator* iterator);
+  void UnregisterIterator(TransactionIterator* iterator);
+  void NotifyIteratorsOfTreeChange();
+
+  LevelDBDatabase* db_;
+  const LevelDBSnapshot snapshot_;
+  const LevelDBComparator* comparator_;
+  TreeType tree_;
+  bool finished_;
+  std::set<TransactionIterator*> iterators_;
+};
+
+class LevelDBWriteOnlyTransaction {
+ public:
+  static scoped_ptr<LevelDBWriteOnlyTransaction> Create(LevelDBDatabase* db);
+
+  ~LevelDBWriteOnlyTransaction();
+  void Remove(const LevelDBSlice& key);
+  bool Commit();
+
+ private:
+  LevelDBWriteOnlyTransaction(LevelDBDatabase* db);
+
+  LevelDBDatabase* db_;
+  scoped_ptr<LevelDBWriteBatch> write_batch_;
+  bool finished_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_INDEXED_DB_LEVELDB_LEVELDB_TRANSACTION_H_