bluetooth: Implement RSSI and Tx Power on macOS and Android

device/bluetooth/bluetooth_adapter_mac.mm

 // Copyright 2013 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.
 
 #include "device/bluetooth/bluetooth_adapter_mac.h"
 
 #import <IOBluetooth/objc/IOBluetoothDevice.h>
 #import <IOBluetooth/objc/IOBluetoothHostController.h>
 #include <stddef.h>
 
@@ skipping 521 matching lines @@
   NSDictionary* service_data =
       [advertisement_data objectForKey:CBAdvertisementDataServiceDataKey];
   for (CBUUID* uuid in service_data) {
     NSData* data = [service_data objectForKey:uuid];
     const uint8_t* bytes = static_cast<const uint8_t*>([data bytes]);
     size_t length = [data length];
     service_data_map.emplace(BluetoothUUID([[uuid UUIDString] UTF8String]),
                              std::vector<uint8_t>(bytes, bytes + length));
   }
 
-  device_mac->UpdateAdvertisementData(std::move(advertised_uuids),
-                                      std::move(service_data_map));
+  // Get Tx Power.
+  NSNumber* tx_power =
+      [advertisement_data objectForKey:CBAdvertisementDataTxPowerLevelKey];
+  base::Optional<int8_t> clamped_tx_power =
+      tx_power == nil ? base::nullopt
+                      : base::make_optional<int8_t>(
+                            BluetoothDevice::ClampPower([tx_power intValue]));

[Jeffrey Yasskin, 2016/08/24 22:32:07]

Same reminder here as on Android. I forget about the details of ObjC, but it's
possible that [tx_power intValue] will return some default when tx_power is nil,
and then you could just write "int8_t clamped_tx_power =
BluetoothDevice::ClampPower([tx_power intValue])"

[ortuno, 2016/08/25 16:42:34]

Done. [tx_power intValue] is 0 when tx_power is nil.

+
+  device_mac->UpdateAdvertisementData(
+      BluetoothDevice::ClampPower(rssi), std::move(advertised_uuids),
+      std::move(service_data_map),
+      clamped_tx_power ? &clamped_tx_power.value() : nullptr);
 
   if (is_new_device) {
     std::string device_address =
         BluetoothLowEnergyDeviceMac::GetPeripheralHashAddress(peripheral);
     devices_.add(device_address, std::unique_ptr<BluetoothDevice>(device_mac));
     FOR_EACH_OBSERVER(BluetoothAdapter::Observer, observers_,
                       DeviceAdded(this, device_mac));
   } else {
     FOR_EACH_OBSERVER(BluetoothAdapter::Observer, observers_,
                       DeviceChanged(this, device_mac));
@@ skipping 71 matching lines @@
   std::string device_address =
       BluetoothLowEnergyDeviceMac::GetPeripheralHashAddress(peripheral);
   DevicesMap::const_iterator iter = devices_.find(device_address);
   if (iter == devices_.end()) {
     return nil;
   }
   return static_cast<BluetoothLowEnergyDeviceMac*>(iter->second);
 }
 
 }  // namespace device