[Smart Lock] Extract the screenlock state to the proximity_auth component.

components/proximity_auth/screenlock_state.h

+// Copyright 2015 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_PROXIMITY_AUTH_SCREENLOCK_STATE_H
+#define COMPONENTS_PROXIMITY_AUTH_SCREENLOCK_STATE_H
+
+namespace proximity_auth {
+
+// Possible states of the proximity auth feature.

[Tim Song, 2015/04/30 23:16:56]

nit: I would rephrase this to say "possible states for a user on the
lock/sign-in screen".

[Ilya Sherman, 2015/05/01 22:33:28]

Done.

+enum class ScreenlockState {
+  // Proximity-based authentication is not enabled, or the screen is not
+  // locked.
+  INACTIVE,
+  // Bluetooth is not on.
+  NO_BLUETOOTH,
+  // The local device is in process of turning on Bluetooth.
+  BLUETOOTH_CONNECTING,
+  // No phones eligible to unlock the local device can be found.
+  NO_PHONE,
+  // A phone eligible to unlock the local device is found, but cannot be
+  // authenticated.
+  PHONE_NOT_AUTHENTICATED,
+  // A phone eligible to unlock the local device is found, but it's locked.
+  PHONE_LOCKED,
+  // A phone eligible to unlock the local device is found, but it does not have
+  // a lock screen enabled.
+  PHONE_NOT_LOCKABLE,
+  // An enabled phone is found, but it is not allowed to unlock the local device
+  // because it does not support reporting its lock screen state.
+  PHONE_UNSUPPORTED,
+  // A phone eligible to unlock the local device is found, but its received
+  // signal strength is too low, i.e. the phone is roughly more than 30 feet
+  // away, and therefore is not allowed to unlock the device.
+  RSSI_TOO_LOW,
+  // A phone eligible to unlock the local device is found, but the local
+  // device's transmission power is too high, indicating that the phone is
+  // (probably) more than 1 foot away, and therefore is not allowed to unlock
+  // the device.
+  TX_POWER_TOO_HIGH,
+  // A phone eligible to unlock the local device is found; but (a) the phone is
+  // locked, and (b) the local device's transmission power is too high,
+  // indicating that the phone is (probably) more than 1 foot away, and
+  // therefore is not allowed to unlock the device.
+  PHONE_LOCKED_AND_TX_POWER_TOO_HIGH,
+  // The local device can be unlocked using proximity-based authentication.
+  AUTHENTICATED,
+};
+
+}  // namespace proximity_auth
+
+#endif  // COMPONENTS_PROXIMITY_AUTH_SCREENLOCK_STATE_H