bluetooth: mac: Improve classic device discovery and update

device/bluetooth/bluetooth_device.cc

Index: device/bluetooth/bluetooth_device.cc
diff --git a/device/bluetooth/bluetooth_device.cc b/device/bluetooth/bluetooth_device.cc
index bdb764dae82b23860bd594846168fc62110ec9e3..6060816375e5884f4608120af99c615efe9c3cba 100644
--- a/device/bluetooth/bluetooth_device.cc
+++ b/device/bluetooth/bluetooth_device.cc
@@ -479,6 +479,10 @@ void BluetoothDevice::UpdateTimestamp() {
   last_update_time_ = base::Time::NowFromSystemTime();
 }
 
+base::Time BluetoothDevice::GetLastUpdateTime() const {
+  return last_update_time_;
+}
+
 // static
 int8_t BluetoothDevice::ClampPower(int power) {
   if (power < INT8_MIN) {