PART1: Initiated the SignedSettings refactoring.

chrome/browser/chromeos/cros_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_CHROMEOS_CROS_SETTINGS_PROVIDER_H_
 #define CHROME_BROWSER_CHROMEOS_CROS_SETTINGS_PROVIDER_H_
 
 #include <string>
 
+#include "base/callback.h"
+
 namespace base {
 class Value;
 }
 
 namespace chromeos {
 
 class CrosSettingsProvider {
  public:
   virtual ~CrosSettingsProvider() {}
 
+  // Callback function type.
+  typedef base::Closure Callback;
+
   // Sets |in_value| to given |path| in cros settings.
   // Note that this takes ownership of |in_value|.
   void Set(const std::string& path, base::Value* in_value);
 
   // Gets settings value of given |path| to |out_value|.
   // Note that |out_value| is owned by the caller, not this class.
-  virtual bool Get(const std::string& path, base::Value** out_value) const = 0;
+  virtual const base::Value* Get(const std::string& path) const = 0;
+
+  // Starts a fetch from the trusted store for the value of |path|. It will
+  // call the |callback| function upon completion.
+  virtual bool GetTrusted(const std::string& path,
+                          const Callback& callback) const = 0;
 
   // Gets the namespace prefix provided by this provider
   virtual bool HandlesSetting(const std::string& path) const = 0;
 
  private:
   // Does the real job for Set().
   virtual void DoSet(const std::string& path, base::Value* in_value) = 0;
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_CROS_SETTINGS_PROVIDER_H_