bluetooth: Change GetInquiryTxPower and GetInquiryRSSI to return optional.

components/arc/common/bluetooth.mojom

 // Copyright 2016 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.
 
 module arc.mojom;
 
 [Extensible]
 enum BluetoothAdapterState {
   OFF = 0,
   ON
@@ skipping 147 matching lines @@
 struct BluetoothGattServiceID {
   BluetoothGattID id;
   uint8 is_primary;
 };
 
 struct BluetoothGattValue {
   BluetoothGattStatus status;
   array<uint8> value;
 };
 
+const int8 kUnknownPower = 127;
+
 // Copy from Bluetooth Assigned Numbers Document, Generic Access Profile
 // https://www.bluetooth.com/specifications/assigned-numbers/generic-access-profile
 [Extensible]
 enum BluetoothAdvertisingDataType {
   DATA_TYPE_FLAGS = 0x01,
   DATA_TYPE_SERVICE_UUIDS_128_BIT_COMPLETE = 0x07,
   DATA_TYPE_LOCAL_NAME_COMPLETE = 0x09,
   DATA_TYPE_TX_POWER_LEVEL = 0x0A,
   DATA_TYPE_SERVICE_DATA = 0x16,
   DATA_TYPE_MANUFACTURER_SPECIFIC_DATA = 0xff,
@@ skipping 183 matching lines @@
                                     int32 attribute_handle,
                                     int32 offset,
                                     bool is_long)
       => (BluetoothGattStatus status, array<uint8> value);
   [MinVersion=3] RequestGattWrite@15(BluetoothAddress address,
                                      int32 attribute_handle,
                                      int32 offset,
                                      array<uint8> value)
       => (BluetoothGattStatus status);
 };