Make drivetrain use generic localizer

This will lead into switching y2019 over to using the Localizer with
camera images.

Change-Id: I2790c09ed9e1cec8d6141c25a4b5a173c2ddc24c
diff --git a/frc971/control_loops/drivetrain/ssdrivetrain.h b/frc971/control_loops/drivetrain/ssdrivetrain.h
index ee8d145..762cbc2 100644
--- a/frc971/control_loops/drivetrain/ssdrivetrain.h
+++ b/frc971/control_loops/drivetrain/ssdrivetrain.h
@@ -11,6 +11,7 @@
 #include "frc971/control_loops/coerce_goal.h"
 #include "frc971/control_loops/drivetrain/drivetrain.q.h"
 #include "frc971/control_loops/drivetrain/drivetrain_config.h"
+#include "frc971/control_loops/drivetrain/localizer.h"
 
 namespace frc971 {
 namespace control_loops {
@@ -20,7 +21,7 @@
  public:
   DrivetrainMotorsSS(const DrivetrainConfig<double> &dt_config,
                      StateFeedbackLoop<7, 2, 4> *kf,
-                     double *integrated_kf_heading);
+                     LocalizerInterface *localizer);
 
   void SetGoal(const ::frc971::control_loops::DrivetrainQueue::Goal &goal);
 
@@ -65,7 +66,7 @@
 
   bool use_profile_ = false;
 
-  double *integrated_kf_heading_;
+  LocalizerInterface *localizer_;
 };
 
 }  // namespace drivetrain