Remove usage of FOR_EACH_OBSERVER macro in device/

device/bluetooth/dbus/fake_bluetooth_gatt_characteristic_client.cc

Index: device/bluetooth/dbus/fake_bluetooth_gatt_characteristic_client.cc
diff --git a/device/bluetooth/dbus/fake_bluetooth_gatt_characteristic_client.cc b/device/bluetooth/dbus/fake_bluetooth_gatt_characteristic_client.cc
index 5953c7e84308b9d72c1cfed196d03f52ba73d52f..e677bcf29297e25a7d03479073d65006f266ebfc 100644
--- a/device/bluetooth/dbus/fake_bluetooth_gatt_characteristic_client.cc
+++ b/device/bluetooth/dbus/fake_bluetooth_gatt_characteristic_client.cc
@@ -454,23 +454,22 @@ void FakeBluetoothGattCharacteristicClient::OnPropertyChanged(
   VLOG(2) << "Characteristic property changed: " << object_path.value() << ": "
           << property_name;
 
-  FOR_EACH_OBSERVER(
-      BluetoothGattCharacteristicClient::Observer, observers_,
-      GattCharacteristicPropertyChanged(object_path, property_name));
+  for (auto& observer : observers_)
+    observer.GattCharacteristicPropertyChanged(object_path, property_name);
 }
 
 void FakeBluetoothGattCharacteristicClient::NotifyCharacteristicAdded(
     const dbus::ObjectPath& object_path) {
   VLOG(2) << "GATT characteristic added: " << object_path.value();
-  FOR_EACH_OBSERVER(BluetoothGattCharacteristicClient::Observer, observers_,
-                    GattCharacteristicAdded(object_path));
+  for (auto& observer : observers_)
+    observer.GattCharacteristicAdded(object_path);
 }
 
 void FakeBluetoothGattCharacteristicClient::NotifyCharacteristicRemoved(
     const dbus::ObjectPath& object_path) {
   VLOG(2) << "GATT characteristic removed: " << object_path.value();
-  FOR_EACH_OBSERVER(BluetoothGattCharacteristicClient::Observer, observers_,
-                    GattCharacteristicRemoved(object_path));
+  for (auto& observer : observers_)
+    observer.GattCharacteristicRemoved(object_path);
 }
 
 void FakeBluetoothGattCharacteristicClient::