Updates touch calibration API and plumbs through the native touch calibration method

chrome/browser/chromeos/display/touch_calibrator/touch_calibrator_controller.h

Index: chrome/browser/chromeos/display/touch_calibrator/touch_calibrator_controller.h
diff --git a/chrome/browser/chromeos/display/touch_calibrator/touch_calibrator_controller.h b/chrome/browser/chromeos/display/touch_calibrator/touch_calibrator_controller.h
index 4f51cd4288237fbf04b6aba4f837398107e2c0cf..75c67295d9c723b11a52ad53be60a5263865fe03 100644
--- a/chrome/browser/chromeos/display/touch_calibrator/touch_calibrator_controller.h
+++ b/chrome/browser/chromeos/display/touch_calibrator/touch_calibrator_controller.h
@@ -31,6 +31,7 @@ class TouchCalibratorController : public ui::EventHandler,
  public:
   using CalibrationPointPairQuad =
       display::TouchCalibrationData::CalibrationPointPairQuad;
+  using TouchCalibrationCallback = base::Callback<void(bool)>;
 
   static const base::TimeDelta kTouchIntervalThreshold;
 
@@ -47,6 +48,10 @@ class TouchCalibratorController : public ui::EventHandler,
   // Starts the calibration process for the given |target_display|.
   void StartCalibration(const display::Display& target_display);
 
+  // Adds a callback that will be called once the calibration has been
+  // completed. This should be called before |StartCalibration()|.
+  void AddCallback(const TouchCalibrationCallback& callback);

[Reilly Grant (use Gerrit), 2017/01/19 02:41:46]

Why not pass this callback to StartCalibration()?

[malaykeshav, 2017/01/19 06:10:38]

I was thinking of making the callback optional in the IDL file, but got lost in
the documentation on to use it. 
Moving the callback to StartCalibration()

+
   // Stops any ongoing calibration process.
   void StopCalibration();
 
@@ -78,6 +83,10 @@ class TouchCalibratorController : public ui::EventHandler,
   // touch input point pairs that will be used for calibration.
   CalibrationPointPairQuad touch_point_quad_;
 
+  // A callback to be called when touch calibration completes.
+  TouchCalibrationCallback callback_;
+  bool has_callback_;

[Reilly Grant (use Gerrit), 2017/01/19 02:41:46]

This field is unnecessary. callback_.is_null() will be true if a callback has
not been set.

[malaykeshav, 2017/01/19 06:10:38]

Done

+
   DISALLOW_COPY_AND_ASSIGN(TouchCalibratorController);
 };