Remove outdated devices from Android device chooser

device/bluetooth/bluetooth_low_energy_device_mac.mm

Index: device/bluetooth/bluetooth_low_energy_device_mac.mm
diff --git a/device/bluetooth/bluetooth_low_energy_device_mac.mm b/device/bluetooth/bluetooth_low_energy_device_mac.mm
index c3d6d1d154dfc5bb6ec9ab61995de7ffc31f34e6..c12cf09a5fb424f223662c48930f09501a3f32c7 100644
--- a/device/bluetooth/bluetooth_low_energy_device_mac.mm
+++ b/device/bluetooth/bluetooth_low_energy_device_mac.mm
@@ -52,7 +52,7 @@ BluetoothLowEnergyDeviceMac::~BluetoothLowEnergyDeviceMac() {
 
 void BluetoothLowEnergyDeviceMac::Update(NSDictionary* advertisement_data,
                                          int rssi) {
-  last_update_time_.reset([[NSDate date] retain]);
+  UpdateTimestamp();
   rssi_ = rssi;
   NSNumber* connectable =
       [advertisement_data objectForKey:CBAdvertisementDataIsConnectable];
@@ -223,10 +223,6 @@ void BluetoothLowEnergyDeviceMac::ConnectToServiceInsecurely(
   NOTIMPLEMENTED();
 }
 
-NSDate* BluetoothLowEnergyDeviceMac::GetLastUpdateTime() const {
-  return last_update_time_.get();
-}
-
 std::string BluetoothLowEnergyDeviceMac::GetDeviceName() const {
   return base::SysNSStringToUTF8([peripheral_ name]);
 }