bluetooth: mac: Improve classic device discovery and update

device/bluetooth/bluetooth_device.h

Index: device/bluetooth/bluetooth_device.h
diff --git a/device/bluetooth/bluetooth_device.h b/device/bluetooth/bluetooth_device.h
index 23565c9b7a804979d7a1da86f8ffcd6d181358b3..b2dfdedce2c0040286c69cac587ad5dff39d2137 100644
--- a/device/bluetooth/bluetooth_device.h
+++ b/device/bluetooth/bluetooth_device.h
@@ -517,8 +517,12 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDevice {
   // empty string.
   static std::string CanonicalizeAddress(const std::string& address);
 
-  // Return the timestamp for when this device was last seen.
-  base::Time GetLastUpdateTime() const { return last_update_time_; }
+  // Update the last time this device was seen.
+  void UpdateTimestamp();
+
+  // Returns the time of the last call to UpdateTimestamp(), or base::Time() if
+  // it hasn't been called yet.
+  virtual base::Time GetLastUpdateTime() const;
 
   // Called by BluetoothAdapter when a new Advertisement is seen for this
   // device. This replaces previously seen Advertisement Data.
@@ -581,9 +585,6 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDevice {
 
   BluetoothDevice(BluetoothAdapter* adapter);
 
-  // Update the last time this device was seen.
-  void UpdateTimestamp();
-
   // Implements platform specific operations to initiate a GATT connection.
   // Subclasses must also call DidConnectGatt, DidFailToConnectGatt, or
   // DidDisconnectGatt immediately or asynchronously as the connection state