diff --git a/common_service.h b/common_service.h
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+//
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_SERVICE_H_
+#define UPDATE_ENGINE_COMMON_SERVICE_H_
+
+#include <inttypes.h>
+
+#include <string>
+
+#include <base/memory/ref_counted.h>
+#include <brillo/errors/error.h>
+
+#include "update_engine/system_state.h"
+
+namespace chromeos_update_engine {
+
+class UpdateEngineService {
+ public:
+  // Flags used in the AttemptUpdateWithFlags() D-Bus method.
+  typedef enum {
+    kAttemptUpdateFlagNonInteractive = (1<<0)
+  } AttemptUpdateFlags;
+
+  // Error domain for all the service errors.
+  static const char* const kErrorDomain;
+
+  // Generic service error.
+  static const char* const kErrorFailed;
+
+  explicit UpdateEngineService(SystemState* system_state);
+  virtual ~UpdateEngineService() = default;
+
+  bool AttemptUpdate(brillo::ErrorPtr* error,
+                     const std::string& in_app_version,
+                     const std::string& in_omaha_url,
+                     int32_t in_flags_as_int);
+
+  bool AttemptRollback(brillo::ErrorPtr* error, bool in_powerwash);
+
+  // Checks if the system rollback is available by verifying if the secondary
+  // system partition is valid and bootable.
+  bool CanRollback(brillo::ErrorPtr* error, bool* out_can_rollback);
+
+  // Resets the status of the update_engine to idle, ignoring any applied
+  // update. This is used for development only.
+  bool ResetStatus(brillo::ErrorPtr* error);
+
+  // Returns the current status of the Update Engine. If an update is in
+  // progress, the number of operations, size to download and overall progress
+  // is reported.
+  bool GetStatus(brillo::ErrorPtr* error,
+                 int64_t* out_last_checked_time,
+                 double* out_progress,
+                 std::string* out_current_operation,
+                 std::string* out_new_version,
+                 int64_t* out_new_size);
+
+  // Reboots the device if an update is applied and a reboot is required.
+  bool RebootIfNeeded(brillo::ErrorPtr* error);
+
+  // Changes the current channel of the device to the target channel. If the
+  // target channel is a less stable channel than the current channel, then the
+  // channel change happens immediately (at the next update check).  If the
+  // target channel is a more stable channel, then if is_powerwash_allowed is
+  // set to true, then also the change happens immediately but with a powerwash
+  // if required. Otherwise, the change takes effect eventually (when the
+  // version on the target channel goes above the version number of what the
+  // device currently has).
+  bool SetChannel(brillo::ErrorPtr* error,
+                  const std::string& in_target_channel,
+                  bool in_is_powerwash_allowed);
+
+  // If get_current_channel is set to true, populates |channel| with the name of
+  // the channel that the device is currently on. Otherwise, it populates it
+  // with the name of the channel the device is supposed to be (in case of a
+  // pending channel change).
+  bool GetChannel(brillo::ErrorPtr* error,
+                  bool in_get_current_channel,
+                  std::string* out_channel);
+
+  // Enables or disables the sharing and consuming updates over P2P feature
+  // according to the |enabled| argument passed.
+  bool SetP2PUpdatePermission(brillo::ErrorPtr* error, bool in_enabled);
+
+  // Returns the current value for the P2P enabled setting. This involves both
+  // sharing and consuming updates over P2P.
+  bool GetP2PUpdatePermission(brillo::ErrorPtr* error, bool* out_enabled);
+
+  // If there's no device policy installed, sets the update over cellular
+  // networks permission to the |allowed| value. Otherwise, this method returns
+  // with an error since this setting is overridden by the applied policy.
+  bool SetUpdateOverCellularPermission(brillo::ErrorPtr* error,
+                                       bool in_allowed);
+
+  // Returns the current value of the update over cellular network setting,
+  // either forced by the device policy if the device is enrolled or the current
+  // user preference otherwise.
+  bool GetUpdateOverCellularPermission(brillo::ErrorPtr* error,
+                                       bool* out_allowed);
+
+  // Returns the duration since the last successful update, as the
+  // duration on the wallclock. Returns an error if the device has not
+  // updated.
+  bool GetDurationSinceUpdate(brillo::ErrorPtr* error,
+                              int64_t* out_usec_wallclock);
+
+  // Returns the version string of OS that was used before the last reboot
+  // into an updated version. This is available only when rebooting into an
+  // update from previous version, otherwise an empty string is returned.
+  bool GetPrevVersion(brillo::ErrorPtr* error, std::string* out_prev_version);
+
+  // Returns the name of kernel partition that can be rolled back into.
+  bool GetRollbackPartition(brillo::ErrorPtr* error,
+                            std::string* out_rollback_partition_name);
+
+ private:
+  SystemState* system_state_;
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_SERVICE_H_