[CrOS Tether] Move the DeviceStatus normalizer code from HostScanner into its own file.

chromeos/components/tether/device_status_util.h

+// Copyright 2017 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_COMPONENTS_TETHER_DEVICE_STATUS_UTIL_H_
+#define CHROMEOS_COMPONENTS_TETHER_DEVICE_STATUS_UTIL_H_
+
+#include "chromeos/components/tether/proto/tether.pb.h"
+
+namespace chromeos {
+
+namespace tether {
+
+// Normalizes the values contained in |device_status| and outputs the normalized
+// values for carrier, battery percentage, and signal strength. The values are
+// normalized according to the following rules:
+//   (1) Carrier: If the proto's cell_provider field is present and non-empty,
+//       it is output; otherwise, the "unknown-carrier" constant is output.
+//   (2) Battery percentage: If the proto's battery_percentage field is present
+//       and within the range [0, 100], it is output; if the field is present
+//       but not in [0, 100], 0 is output if the input is <0 and 100 is output
+//       if the input is >100; if the field is not present, 100 is output.
+//   (3) Signal strength: If the proto's connection_strength field is present
+//       and within the range [0, 4], it is multiplied by 25 and output in a new
+//       range [0, 100]; if the field is present but not in [0, 4], 0 is output
+//       if the input is <0 and 100 is output if the input >4; if the field is
+//       not present, 100 is output. Note that the multipier is needed because
+//       Android's connection strength is a value from 0 to 4, while Chrome OS's
+//       signal strength ranges from 0 to 100.
+void NormalizeDeviceStatus(const DeviceStatus& status,
+                           std::string* carrier_out,
+                           int32_t* battery_percentage_out,
+                           int32_t* signal_strength_out);
+
+}  // namespace tether
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_COMPONENTS_TETHER_DEVICE_STATUS_UTIL_H_