[Sync] Replace typedef with using.

components/sync/base/node_ordinal.h

 // Copyright 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 COMPONENTS_SYNC_BASE_NODE_ORDINAL_H_
 #define COMPONENTS_SYNC_BASE_NODE_ORDINAL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "components/sync/base/ordinal.h"
 
 namespace syncer {
 
 // A NodeOrdinal is an Ordinal whose internal value comes from the
 // ordinal_in_parent field of SyncEntity (see sync.proto).  It uses
 // the entire uint8_t range for backwards compatibility with the old
 // int64_t-based positioning.
 
 struct NodeOrdinalTraits {
   static const uint8_t kZeroDigit = 0;
   static const uint8_t kMaxDigit = UINT8_MAX;
   static const size_t kMinLength = 8;
 };
 
-typedef Ordinal<NodeOrdinalTraits> NodeOrdinal;
+using NodeOrdinal = Ordinal<NodeOrdinalTraits>;
 
 static_assert(static_cast<char>(NodeOrdinal::kZeroDigit) == '\x00',
               "NodeOrdinal has incorrect zero digit");
 static_assert(static_cast<char>(NodeOrdinal::kOneDigit) == '\x01',
               "NodeOrdinal has incorrect one digit");
 static_assert(static_cast<char>(NodeOrdinal::kMidDigit) == '\x80',
               "NodeOrdinal has incorrect mid digit");
 static_assert(static_cast<char>(NodeOrdinal::kMaxDigit) == '\xff',
               "NodeOrdinal has incorrect max digit");
 static_assert(NodeOrdinal::kMidDigitValue == 128,
@@ skipping 10 matching lines @@
 
 // The inverse of Int64ToNodeOrdinal.  This conversion is, in general,
 // lossy: NodeOrdinals can have arbitrary fidelity, while numeric
 // positions contain only 64 bits of information (in fact, this is the
 // reason we've moved away from them).
 int64_t NodeOrdinalToInt64(const NodeOrdinal& ordinal);
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_BASE_NODE_ORDINAL_H_