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diff --git a/chrome/browser/chromeos/settings/cros_settings_provider.h b/chrome/browser/chromeos/settings/cros_settings_provider.h
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+++ b/chrome/browser/chromeos/settings/cros_settings_provider.h
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+// 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 CHROME_BROWSER_CHROMEOS_SETTINGS_CROS_SETTINGS_PROVIDER_H_
+#define CHROME_BROWSER_CHROMEOS_SETTINGS_CROS_SETTINGS_PROVIDER_H_
+
+#include <string>
+
+#include "base/callback.h"
+
+namespace base {
+class Value;
+}
+
+namespace chromeos {
+
+class CrosSettingsProvider {
+ public:
+  // The callback type that is called to notify the CrosSettings observers
+  // about a setting change.
+  typedef base::Callback<void(const std::string&)> NotifyObserversCallback;
+
+  // Possible results of a trusted check.
+  enum TrustedStatus {
+    // The trusted values were populated in the cache and can be accessed
+    // until the next iteration of the message loop.
+    TRUSTED,
+    // Either a store or a load operation is in progress. The provided
+    // callback will be invoked once the verification has finished.
+    TEMPORARILY_UNTRUSTED,
+    // The verification of the trusted store has failed permanently. The
+    // client should assume this state final and further checks for
+    // trustedness will fail at least until the browser restarts.
+    PERMANENTLY_UNTRUSTED,
+  };
+
+  // Creates a new provider instance. |notify_cb| will be used to notify
+  // about setting changes.
+  explicit CrosSettingsProvider(const NotifyObserversCallback& notify_cb);
+  virtual ~CrosSettingsProvider();
+
+  // Sets |in_value| to given |path| in cros settings.
+  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;
+
+  // Requests the provider to fetch its values from a trusted store, if it
+  // hasn't done so yet. Returns TRUSTED if the values returned by this provider
+  // are trusted during the current loop cycle. Otherwise returns
+  // TEMPORARILY_UNTRUSTED, and |callback| will be invoked later when trusted
+  // values become available, PrepareTrustedValues() should be tried again in
+  // that case. Returns PERMANENTLY_UNTRUSTED if a permanent error has occurred.
+  virtual TrustedStatus PrepareTrustedValues(
+      const base::Closure& callback) = 0;
+
+  // Gets the namespace prefix provided by this provider.
+  virtual bool HandlesSetting(const std::string& path) const = 0;
+
+  // Reloads the caches if the provider has any.
+  virtual void Reload() = 0;
+
+  void SetNotifyObserversCallback(const NotifyObserversCallback& notify_cb);
+
+ protected:
+  // Notifies the observers about a setting change.
+  void NotifyObservers(const std::string& path);
+
+ private:
+  // Does the real job for Set().
+  virtual void DoSet(const std::string& path,
+                     const base::Value& in_value) = 0;
+
+  // Callback used to notify about setting changes.
+  NotifyObserversCallback notify_cb_;
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_SETTINGS_CROS_SETTINGS_PROVIDER_H_