Pass MotionEvent tilt angles to Blink on Android.

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 12834a793f2db1e51e2af8a621fb98c139bdb32c..6ac0b655bfc654949cbbca11b8cb1a07fe5a2a53 100644
--- a/ui/events/gesture_detection/motion_event.h
+++ b/ui/events/gesture_detection/motion_event.h
@@ -62,6 +62,12 @@ 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;
+  // TODO(e_hakkinen): Remove either GetTilt and GetTiltOrientation or GetTiltX
+  //                   and GetTiltY.
+  virtual float GetTilt(size_t pointer_index) const = 0;

[mustaq, 2015/06/17 20:01:27]

Since the discussion in crrev.com/1147083005 showed a strong support to keep the
MotionEvent interface as close to the Android spec as possible, I would add only
GetTilt() here, and untangle the overloaded orientation angle while converting
to other types, as I commented in blink_event_util.cc.

Sorry for my changed position in this regard.

Do you know if blink_event_util.cc is the only place to convert from MotionEvent
to other point-types? 

[USE eero AT chromium.org, 2015/06/18 11:34:07]

Done.

Initially I thought that WebTouchPoint to MotionEventWeb conversion very
complex,
but that conversion is actually used only for touch events and even if it would
be extended to all pointer events, conversion would not be that complex.
It would be enough to check signs of tiltX and tiltY. Trigonometry would not be
needed.
Seems to be so.

+  virtual float GetTiltOrientation(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;
@@ -100,6 +106,14 @@ class GESTURE_DETECTION_EXPORT MotionEvent {
   float GetOrientation() const { return GetOrientation(0); }
 
   float GetPressure() const { return GetPressure(0); }
+
+  // TODO(e_hakkinen): Remove either GetTilt and GetTiltOrientation or GetTiltX
+  //                   and GetTiltY.
+  float GetTilt() const { return GetTilt(0); }
+  float GetTiltOrientation() const { return GetTiltOrientation(0); }
+  float GetTiltY() const { return GetTiltX(0); }
+  float GetTiltX() const { return GetTiltY(0); }
+
   ToolType GetToolType() const { return GetToolType(0); }
 
   // O(N) search of pointers (use sparingly!). Returns -1 if |id| nonexistent.