Rewrite DefaultPrefStore for performance

base/prefs/default_pref_store.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 BASE_PREFS_DEFAULT_PREF_STORE_H_
 #define BASE_PREFS_DEFAULT_PREF_STORE_H_
 
 #include <string>
 
 #include "base/prefs/base_prefs_export.h"
-#include "base/prefs/value_map_pref_store.h"
+#include "base/prefs/pref_store.h"
+#include "base/prefs/pref_value_map.h"
 #include "base/values.h"
 
 // This PrefStore keeps track of default preference values set when a
 // preference is registered with the PrefService.
-class BASE_PREFS_EXPORT DefaultPrefStore : public ValueMapPrefStore {
+class BASE_PREFS_EXPORT DefaultPrefStore : public PrefStore {
  public:
+  typedef PrefValueMap::const_iterator const_iterator;
+
   DefaultPrefStore();
 

[battre, 2012/11/07 11:50:49]

nit: // Implementation of PrefStore.

+  virtual ReadResult GetValue(const std::string& key,
+                              const base::Value** result) const OVERRIDE;
+
   // Stores a new |value| for |key|. Assumes ownership of |value|.
   void SetDefaultValue(const std::string& key, Value* value);
 
   // Removes the value for |key|.
   void RemoveDefaultValue(const std::string& key);
 
   // Returns the registered type for |key| or Value::TYPE_NULL if the |key|
   // has not been registered.
   base::Value::Type GetType(const std::string& key) const;
 
+  const_iterator begin() const;
+  const_iterator end() const;
+
  protected:
   virtual ~DefaultPrefStore();
 
  private:
+  PrefValueMap prefs_;
+
   DISALLOW_COPY_AND_ASSIGN(DefaultPrefStore);
 };
 
 #endif  // BASE_PREFS_DEFAULT_PREF_STORE_H_