Changed DB to store node positions as Ordinals.

sync/internal_api/public/base/ordinal.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_INTERNAL_API_PUBLIC_BASE_ORDINAL_H_
 #define SYNC_INTERNAL_API_PUBLIC_BASE_ORDINAL_H_
 
 #include <algorithm>
 #include <cstddef>
 #include <string>
@@ skipping 60 matching lines @@
     EqualsFn();
 
     bool operator()(const Ordinal<Traits>& lhs,
                     const Ordinal<Traits>& rhs) const;
   };
 
   // Creates an Ordinal from the given string of bytes. The Ordinal
   // may be valid or invalid.
   explicit Ordinal(const std::string& bytes);
 
-  // Creates an invalid Ordinal.
+  // Creates an invalid Ordinal

[akalin, 2012/10/08 21:09:46]

revert diff (add the period back in)

   Ordinal();
 
   // Creates a valid initial Ordinal. This is called to create the first
   // element of Ordinal list (i.e. before we have any other values we can
   // generate from).
   static Ordinal CreateInitialOrdinal();
 
   // Returns true iff this Ordinal is valid.  This takes constant
   // time.
   bool IsValid() const;
@@ skipping 385 matching lines @@
   DCHECK_LT(midpoint, end_bytes);
 
   Ordinal<Traits> midpoint_ordinal(midpoint);
   DCHECK(midpoint_ordinal.IsValid());
   return midpoint_ordinal;
 }
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_BASE_ORDINAL_H_