cros: Clean up TrayBluetoothHelper todos

ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.cc

Index: ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.cc
diff --git a/ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.cc b/ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.cc
index 3ee07f53c57fe8c61c914b216eb17c5dc6eb7afc..9af326d6df1d0b2c2b02192cc82bb90b226cd724 100644
--- a/ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.cc
+++ b/ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.cc
@@ -60,10 +60,9 @@ void TrayBluetoothHelper::InitializeOnAdapterReady(
   adapter_->AddObserver(this);
 }
 
-void TrayBluetoothHelper::GetAvailableBluetoothDevices(
-    std::vector<BluetoothDeviceInfo>* list) {
-  device::BluetoothAdapter::DeviceList devices = adapter_->GetDevices();
-  for (device::BluetoothDevice* device : devices) {
+BluetoothDeviceList TrayBluetoothHelper::GetAvailableBluetoothDevices() const {
+  BluetoothDeviceList list;
+  for (device::BluetoothDevice* device : adapter_->GetDevices()) {
     BluetoothDeviceInfo info;
     info.address = device->GetAddress();
     info.display_name = device->GetNameForDisplay();
@@ -71,8 +70,9 @@ void TrayBluetoothHelper::GetAvailableBluetoothDevices(
     info.connecting = device->IsConnecting();
     info.paired = device->IsPaired();
     info.device_type = device->GetDeviceType();
-    list->push_back(info);
+    list.push_back(info);
   }
+  return list;
 }
 
 void TrayBluetoothHelper::StartBluetoothDiscovering() {