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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_POLICY_POLICY_SERVICE_H_
#define CHROME_BROWSER_POLICY_POLICY_SERVICE_H_
#pragma once
#include <map>
#include <string>
#include "base/basictypes.h"
#include "base/callback.h"
#include "chrome/browser/policy/policy_map.h"
namespace policy {
// Policies are namespaced by a (PolicyDomain, ID) pair. The meaning of the ID
// string depends on the domain; for example, if the PolicyDomain is
// "extensions" then the ID identifies the extension that the policies control.
enum PolicyDomain {
// The component ID for chrome policies is always the empty string.
POLICY_DOMAIN_CHROME,
// The extensions policy domain is a work in progress. Included here for
// tests.
POLICY_DOMAIN_EXTENSIONS,
};
// The PolicyService merges policies from all available sources, taking into
// account their priorities. Policy clients can retrieve policy for their domain
// and register for notifications on policy updates.
//
// The PolicyService is available from BrowserProcess as a global singleton.
class PolicyService {
public:
class Observer {
public:
virtual ~Observer() {}
// Invoked whenever policies for the |domain|, |component_id| namespace are
// modified. This is only invoked for changes that happen after AddObserver
// is called. |previous| contains the values of the policies before the
// update, and |current| contains the current values.
virtual void OnPolicyUpdated(PolicyDomain domain,
const std::string& component_id,
const PolicyMap& previous,
const PolicyMap& current) = 0;
// Invoked at most once, when the PolicyService becomes ready. If
// IsInitializationComplete() is false, then this will be invoked once all
// the policy providers are ready.
virtual void OnPolicyServiceInitialized() {}
};
virtual ~PolicyService() {}
virtual void AddObserver(PolicyDomain domain,
const std::string& component_id,
Observer* observer) = 0;
virtual void RemoveObserver(PolicyDomain domain,
const std::string& component_id,
Observer* observer) = 0;
virtual const PolicyMap& GetPolicies(
PolicyDomain domain,
const std::string& component_id) const = 0;
// The PolicyService loads policy from several sources, and some require
// asynchronous loads. IsInitializationComplete() returns true once all
// sources have loaded their policies. It is safe to read policy from the
// PolicyService even if IsInitializationComplete() is false; there will be an
// OnPolicyUpdated() notification once new policies become available.
//
// OnPolicyServiceInitialized() is called when IsInitializationComplete()
// becomes true, which happens at most once. If IsInitializationComplete() is
// already true when an Observer is registered, then that Observer will not
// have a OnPolicyServiceInitialized() notification.
virtual bool IsInitializationComplete() const = 0;
// Asks the PolicyService to reload policy from all available policy sources.
// |callback| is invoked once every source has reloaded its policies, and
// GetPolicies() is guaranteed to return the updated values at that point.
virtual void RefreshPolicies(const base::Closure& callback) = 0;
};
// A registrar that only observes changes to particular policies within the
// PolicyMap for the given policy namespace.
class PolicyChangeRegistrar : public PolicyService::Observer {
public:
typedef base::Callback<void(const Value*, const Value*)> UpdateCallback;
// Observes updates to the given (domain, component_id) namespace in the given
// |policy_service|, and notifies |observer| whenever any of the registered
// policy keys changes. Both the |policy_service| and the |observer| must
// outlive |this|.
PolicyChangeRegistrar(PolicyService* policy_service,
PolicyDomain domain,
const std::string& component_id);
virtual ~PolicyChangeRegistrar();
// Will invoke |callback| whenever |policy_name| changes its value, as long
// as this registrar exists.
// Only one callback can be registed per policy name; a second call with the
// same |policy_name| will overwrite the previous callback.
void Observe(const std::string& policy_name, const UpdateCallback& callback);
// Implementation of PolicyService::Observer:
virtual void OnPolicyUpdated(PolicyDomain domain,
const std::string& component_id,
const PolicyMap& previous,
const PolicyMap& current) OVERRIDE;
private:
typedef std::map<std::string, UpdateCallback> CallbackMap;
PolicyService* policy_service_;
PolicyDomain domain_;
std::string component_id_;
CallbackMap callback_map_;
DISALLOW_COPY_AND_ASSIGN(PolicyChangeRegistrar);
};
} // namespace policy
#endif // CHROME_BROWSER_POLICY_POLICY_SERVICE_H_
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