Pass through tilt_x and tilt_y to blink

ui/events/gesture_detection/motion_event.h

Index: ui/events/gesture_detection/motion_event.h
diff --git a/ui/events/gesture_detection/motion_event.h b/ui/events/gesture_detection/motion_event.h
index f38cb96c1a290775a541bb9ccebaa6b1a8669f9b..673cd8c14591c83cbc45360738bc548a149b9613 100644
--- a/ui/events/gesture_detection/motion_event.h
+++ b/ui/events/gesture_detection/motion_event.h
@@ -76,7 +76,8 @@ class GESTURE_DETECTION_EXPORT MotionEvent {
   virtual float GetTouchMinor(size_t pointer_index) const = 0;
   virtual float GetOrientation(size_t pointer_index) const = 0;
   virtual float GetPressure(size_t pointer_index) const = 0;
-  virtual float GetTilt(size_t pointer_index) const = 0;
+  virtual float GetTiltX(size_t pointer_index) const = 0;
+  virtual float GetTiltY(size_t pointer_index) const = 0;
   virtual ToolType GetToolType(size_t pointer_index) const = 0;
   virtual int GetButtonState() const = 0;
   virtual int GetFlags() const = 0;
@@ -115,7 +116,8 @@ class GESTURE_DETECTION_EXPORT MotionEvent {
   float GetOrientation() const { return GetOrientation(0); }
 
   float GetPressure() const { return GetPressure(0); }
-  float GetTilt() const { return GetTilt(0); }
+  float GetTiltX() const { return GetTiltX(0); }

[use mustaq_at_chromium.org, 2017/05/15 19:46:53]

We need a clear description here because these angle values in degrees is
neither in the spec nor consistent with the rest of the angles here.

Please say something like this:

"We have GetTiltX/Y here instead of GetTilt because MotionEvent spec is not
expressive enough for both 2D touch-surface geometry and 3D pen-orientation
geometry, as needed for PointerEvents:
https://w3c.github.io/pointerevents

Both GetTiltX and GetTiltY return angles in **degrees**, in the range [-90,90].
See the PointerEvent spec link above for details."

[jkwang, 2017/05/16 01:13:26]

Done.

+  float GetTiltY() const { return GetTiltY(0); }
   ToolType GetToolType() const { return GetToolType(0); }
 
   // O(N) search of pointers (use sparingly!). Returns -1 if |id| nonexistent.