PART2: Make SignedSettings use proper Value types instead of string all around the place.

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() {}
 
   // 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);
+  void Set(const std::string& path, const base::Value& in_value);
 
   // Gets settings value of given |path| to |out_value|.
   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.
+  // Starts a fetch from the trusted store for the value of |path| if not loaded
+  // yet. It will call the |callback| function upon completion if a new fetch
+  // was needed in which case the return value is false. Else it will return
+  // true and won't call the |callback|.
   virtual bool GetTrusted(const std::string& path,
                           const base::Closure& 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;
+  virtual void DoSet(const std::string& path,
+                     const base::Value& in_value) = 0;
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_CROS_SETTINGS_PROVIDER_H_