Adds touch calibration methods to system_display.idl API

extensions/common/api/system_display.idl

Index: extensions/common/api/system_display.idl
diff --git a/extensions/common/api/system_display.idl b/extensions/common/api/system_display.idl
index b0600f4972c20a97a8da071fbdb40de89a9561b8..bd9654f604ddcfd28183c2d3feb692548ecc6721 100644
--- a/extensions/common/api/system_display.idl
+++ b/extensions/common/api/system_display.idl
@@ -33,6 +33,36 @@ namespace system.display {
     long bottom;
   };
 
+  dictionary Point {
+    // The x-coordinate of the point.
+    long x;
+
+    // The y-coordinate of the point.
+    long y;
+  };
+
+  dictionary TouchCalibrationPair {
+    // The coordinates of the display point.
+    Point displayPoint;
+
+    // The coordinates of the touch point corresponding to the display point.
+    Point touchPoint;
+  };
+
+  dictionary TouchCalibrationPairQuad {
+    // First pair of touch and display point required for touch calibration.
+    TouchCalibrationPair pair1;
+
+    // Second pair of touch and display point required for touch calibration.
+    TouchCalibrationPair pair2;
+
+    // Third pair of touch and display point required for touch calibration.
+    TouchCalibrationPair pair3;
+
+    // Fourth pair of touch and display point required for touch calibration.
+    TouchCalibrationPair pair4;
+  };
+
   dictionary DisplayMode {
     // The display mode width in device independent (user visible) pixels.
     long width;
@@ -242,6 +272,28 @@ namespace system.display {
     // and hiding the overlay.
     // |id|: The display's unique identifier.
     static void overscanCalibrationComplete(DOMString id);
+
+    // Starts touch calibration for a display. This will show an overlay on the
+    // screen and initialize the UX for touch calibration. If touch calibration
+    // for display |id| is already in progress this will throw an error.

[asargent_no_longer_on_chrome, 2016/12/01 00:38:36]

Would the correct thing be for a developer to call touchCalibrationReset if
calibration is already in progress and this returned an error? If so that might
be worth mentioning in the comment. 

[malaykeshav, 2016/12/01 00:42:22]

The only way to quit the calibration is by some kind of user input, that is,
either by pressing the escape key or by completing the calibration process that
is under progress.

+    // |id|: The display's unique identifier.
+    static void touchCalibrationStart(DOMString id);
+
+    // Sets the touch calibration pairs for a display. These |pairs| would be
+    // used to calibrate the touch screen for display |id|. If touch calibration
+    // for display |id| is in progress this will do nothing.
+    // |id|: The display's unique identifier.
+    // |pairs|: The pairs of point used to calibrate the display.
+    // |bounds|: Bounds of the display when the touch calibration was performed.
+    //     |bounds.left| and |bounds.top| values are ignored.
+    static void touchCalibrationSet(DOMString id,
+                                    TouchCalibrationPairQuad pairs,
+                                    Bounds bounds);
+
+    // Resets the touch calibration for the display and removes the saved
+    // calibration data.
+    // |id|: The display's unique identifier.
+    static void touchCalibrationReset(DOMString id);
   };
 
   interface Events {