[sensors] Add GetDefaultConfiguration() to generic sensor mojo interface.

device/generic_sensor/sensor_impl.h

Index: device/generic_sensor/sensor_impl.h
diff --git a/device/generic_sensor/sensor_impl.h b/device/generic_sensor/sensor_impl.h
index cf5284b15952873592f9a2d2b18d7e9bfec4ca6a..ea501236014d5761f943fc1d82f25f3cacdf1013 100644
--- a/device/generic_sensor/sensor_impl.h
+++ b/device/generic_sensor/sensor_impl.h
@@ -26,6 +26,8 @@ class SensorImpl final : public mojom::Sensor, public PlatformSensor::Client {
   // Sensor implementation.
   void AddConfiguration(const PlatformSensorConfiguration& configuration,
                         const AddConfigurationCallback& callback) override;
+  void GetDefaultConfiguration(
+      const GetDefaultConfigurationCallback& callback) override;
   void RemoveConfiguration(
       const PlatformSensorConfiguration& configuration,
       const RemoveConfigurationCallback& callback) override;