Update from https://crrev.com/327068

base/prefs/pref_value_map.h

 // Copyright (c) 2011 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 BASE_PREFS_PREF_VALUE_MAP_H_
 #define BASE_PREFS_PREF_VALUE_MAP_H_
 
-#include <map>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/containers/hash_tables.h"
 #include "base/prefs/base_prefs_export.h"
 
 namespace base {
 class Value;
 }
 
 // A generic string to value map used by the PrefStore implementations.
 class BASE_PREFS_EXPORT PrefValueMap {
  public:
-  typedef std::map<std::string, base::Value*>::iterator iterator;
-  typedef std::map<std::string, base::Value*>::const_iterator const_iterator;
+  using Map = base::hash_map<std::string, base::Value*>;
+  using iterator = Map::iterator;
+  using const_iterator = Map::const_iterator;
 
   PrefValueMap();
   virtual ~PrefValueMap();
 
   // Gets the value for |key| and stores it in |value|. Ownership remains with
   // the map. Returns true if a value is present. If not, |value| is not
   // touched.
   bool GetValue(const std::string& key, const base::Value** value) const;
   bool GetValue(const std::string& key, base::Value** value);
 
@@ skipping 40 matching lines @@
   // Sets the value for |key| to the double |value|.
   void SetDouble(const std::string& key, const double value);
 
   // Compares this value map against |other| and stores all key names that have
   // different values in |differing_keys|. This includes keys that are present
   // only in one of the maps.
   void GetDifferingKeys(const PrefValueMap* other,
                         std::vector<std::string>* differing_keys) const;
 
  private:
-  typedef std::map<std::string, base::Value*> Map;
-
   Map prefs_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefValueMap);
 };
 
 #endif  // BASE_PREFS_PREF_VALUE_MAP_H_