cros: Clean up TrayBluetoothHelper todos

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

Index: ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.h
diff --git a/ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.h b/ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.h
index 6add0d71e66a8fdfd0e47aa44ce11842cc8a39cb..3391b177ff19333e38021acd4e6b84e3a11a2571 100644
--- a/ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.h
+++ b/ash/common/system/chromeos/bluetooth/tray_bluetooth_helper.h
@@ -20,8 +20,9 @@ class BluetoothDiscoverySession;
 
 namespace ash {
 
-// TODO(jamescook): Convert TrayBlueooth to use device::BluetoothDevice and
-// delete this. http://crbug.com/660043
+// Cached info from device::BluetoothDevice used for display in the UI.
+// Exists because it is not safe to cache pointers to device::BluetoothDevice
+// instances.
 struct ASH_EXPORT BluetoothDeviceInfo {

[James Cook, 2017/03/21 23:35:35]

It's possible this struct could be eliminated by making TrayBluetooth store
lists of device addresses instead of lists of this struct. However, the UI would
have to look up the device info from the adapter every time it does something.
I'm concerned that there may be cases where the UI transiently needs to display
a device that just disconnected from the adapter. Also, there are no tests of
TrayBluetooth. So I don't think this is worth "fixing".

[msw, 2017/03/21 23:48:41]

Acknowledged.

   BluetoothDeviceInfo();
   BluetoothDeviceInfo(const BluetoothDeviceInfo& other);
@@ -55,8 +56,7 @@ class ASH_EXPORT TrayBluetoothHelper
       scoped_refptr<device::BluetoothAdapter> adapter);
 
   // Returns a list of available bluetooth devices.
-  // TODO(jamescook): Just return the list.
-  void GetAvailableBluetoothDevices(std::vector<BluetoothDeviceInfo>* list);
+  BluetoothDeviceList GetAvailableBluetoothDevices() const;
 
   // Requests bluetooth start discovering devices, which happens asynchronously.
   void StartBluetoothDiscovering();