PART1: Initiated the SignedSettings refactoring.

chrome/browser/ui/webui/options/chromeos/system_settings_provider.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 CHROME_BROWSER_UI_WEBUI_OPTIONS_CHROMEOS_SYSTEM_SETTINGS_PROVIDER_H_
 #define CHROME_BROWSER_UI_WEBUI_OPTIONS_CHROMEOS_SYSTEM_SETTINGS_PROVIDER_H_
 
 #include <vector>
 
+#include "base/callback.h"
 #include "base/string16.h"
 #include "chrome/browser/chromeos/cros_settings_provider.h"
 #include "chrome/browser/chromeos/system/timezone_settings.h"
 #include "third_party/icu/public/i18n/unicode/timezone.h"
 
 namespace base {
 class Value;
 class ListValue;
+class StringValue;
 }
 
 namespace chromeos {
 
 class SystemSettingsProvider : public CrosSettingsProvider,
                                public system::TimezoneSettings::Observer {
  public:
   SystemSettingsProvider();
   virtual ~SystemSettingsProvider();
 
   // CrosSettingsProvider overrides.
-  virtual bool Get(const std::string& path,
-                   base::Value** out_value) const OVERRIDE;
+  virtual const base::Value* Get(const std::string& path) const OVERRIDE;
+  virtual bool GetTrusted(const std::string& path,
+                          const base::Closure& callback) const OVERRIDE;
   virtual bool HandlesSetting(const std::string& path) const OVERRIDE;
 
   // Overridden from TimezoneSettings::Observer:
   virtual void TimezoneChanged(const icu::TimeZone& timezone) OVERRIDE;
 
   // Creates the map of timezones used by the options page.
   base::ListValue* GetTimezoneList();
 
  private:
   // CrosSettingsProvider overrides.
@@ skipping 12 matching lines @@
   // rule of given |timezone|.
   // One timezone could have multiple timezones,
   // e.g.
   //   US/Pacific == America/Los_Angeles
   // We should always use the known timezone id when passing back as
   // pref values.
   string16 GetKnownTimezoneID(const icu::TimeZone& timezone) const;
 
   // Timezones.
   std::vector<icu::TimeZone*> timezones_;
+  // TODO(pastarmovj): This will be cached into the local_store soon.

[Mattias Nissler (ping if slow), 2011/11/18 14:12:00]

What's the local_store? you mean local state PrefService?

[pastarmovj, 2011/11/18 15:01:38]

True. Changed.

+  mutable scoped_ptr<base::StringValue> system_timezone_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemSettingsProvider);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_OPTIONS_CHROMEOS_SYSTEM_SETTINGS_PROVIDER_H_