components/sync/device_info/local_device_info_provider.h

// Copyright 2014 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 COMPONENTS_SYNC_DEVICE_INFO_LOCAL_DEVICE_INFO_PROVIDER_H_
#define COMPONENTS_SYNC_DEVICE_INFO_LOCAL_DEVICE_INFO_PROVIDER_H_

#include <memory>
#include <string>

#include "base/callback_list.h"

namespace syncer {

class DeviceInfo;

// Interface for providing sync specific information about the
// local device.
class LocalDeviceInfoProvider {
 public:
  using Subscription = base::CallbackList<void(void)>::Subscription;

  virtual ~LocalDeviceInfoProvider() {}

  // Returns sync's representation of the local device info, or nullptr if the
  // device info is unavailable. The returned object is fully owned by
  // LocalDeviceInfoProvider; it must not be freed by the caller and should not
  // be stored.
  virtual const DeviceInfo* GetLocalDeviceInfo() const = 0;

  // Constructs a user agent string (ASCII) suitable for use by the syncapi
  // for any HTTP communication. This string is used by the sync backend for
  // classifying client types when calculating statistics.
  virtual std::string GetSyncUserAgent() const = 0;

  // Returns a GUID string used for creation of the machine tag for
  // this local session; an empty sting if LocalDeviceInfoProvider hasn't been
  // initialized yet.
  virtual std::string GetLocalSyncCacheGUID() const = 0;

  // Starts initializing local device info.
  virtual void Initialize(const std::string& cache_guid,
                          const std::string& signin_scoped_device_id) = 0;

  // Registers a callback to be called when local device info becomes available.
  // The callback will remain registered until the
  // returned Subscription is destroyed, which must occur before the
  // CallbackList is destroyed.
  virtual std::unique_ptr<Subscription> RegisterOnInitializedCallback(
      const base::Closure& callback) = 0;

  // Clears all cached data, returning to an uninitialized state.
  virtual void Clear() = 0;
};

}  // namespace syncer

#endif  // COMPONENTS_SYNC_DEVICE_INFO_LOCAL_DEVICE_INFO_PROVIDER_H_