// Copyright 2013 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 CHROMEOS_SETTINGS_CROS_SETTINGS_PROVIDER_H_
#define CHROMEOS_SETTINGS_CROS_SETTINGS_PROVIDER_H_
#include <string>
#include "base/callback.h"
#include "chromeos/chromeos_export.h"
namespace base {
class Value;
}
namespace chromeos {
class CHROMEOS_EXPORT 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;
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 // CHROMEOS_SETTINGS_CROS_SETTINGS_PROVIDER_H_