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

device/generic_sensor/sensor_impl.cc

Index: device/generic_sensor/sensor_impl.cc
diff --git a/device/generic_sensor/sensor_impl.cc b/device/generic_sensor/sensor_impl.cc
index dccd79d80d20436a25a34ebb4750c29ab4abdfb4..c666aec8958a9d6a8a8988623f1a81e5175d2b90 100644
--- a/device/generic_sensor/sensor_impl.cc
+++ b/device/generic_sensor/sensor_impl.cc
@@ -32,6 +32,11 @@ void SensorImpl::AddConfiguration(
   callback.Run(sensor_->StartListening(this, configuration));
 }
 
+void SensorImpl::GetDefaultConfiguration(
+    const GetDefaultConfigurationCallback& callback) {
+  callback.Run(sensor_->GetDefaultConfiguration());
+}
+
 void SensorImpl::RemoveConfiguration(
     const PlatformSensorConfiguration& configuration,
     const RemoveConfigurationCallback& callback) {