Indexed DB: Simplify cursor iteration logic

content/browser/indexed_db/indexed_db_backing_store.h

 // 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_INDEXED_DB_BACKING_STORE_H_
 #define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_BACKING_STORE_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 320 matching lines @@
 
     IndexedDBBackingStore* backing_store_;
     Transaction* transaction_;
     int64 database_id_;
     const CursorOptions cursor_options_;
     scoped_ptr<LevelDBIterator> iterator_;
     scoped_ptr<IndexedDBKey> current_key_;
     IndexedDBBackingStore::RecordIdentifier record_identifier_;
 
    private:
+    // For cursors with direction Next or NextNoDuplicate.
+    bool ContinueNext(const IndexedDBKey* key,
+                      const IndexedDBKey* primary_key,
+                      IteratorState state,
+                      leveldb::Status*);
+    // For cursors with direction Prev or PrevNoDuplicate.
+    // The PrevNoDuplicate case has additional complexity of not
+    // being symmetric with NextNoDuplicate.
+    bool ContinuePrevious(const IndexedDBKey* key,
+                          const IndexedDBKey* primary_key,
+                          IteratorState state,
+                          leveldb::Status*);
+
     DISALLOW_COPY_AND_ASSIGN(Cursor);
   };
 
   const GURL& origin_url() const { return origin_url_; }
   IndexedDBFactory* factory() const { return indexed_db_factory_; }
   base::SequencedTaskRunner* task_runner() const { return task_runner_.get(); }
   base::OneShotTimer<IndexedDBBackingStore>* close_timer() {
     return &close_timer_;
   }
   IndexedDBActiveBlobRegistry* active_blob_registry() {
@@ skipping 301 matching lines @@
   // complete. While > 0, temporary journal entries may exist so out-of-band
   // journal cleaning must be deferred.
   size_t committing_transaction_count_;
 
   DISALLOW_COPY_AND_ASSIGN(IndexedDBBackingStore);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_BACKING_STORE_H_