Pass real tilt information to PointerEvents.

Source/web/WebInputEventConversion.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 411 matching lines @@
 
     // This assumes convertFromContainingWindow does only translations, not scales.
     FloatPoint floatPos = convertHitPointToWindow(widget, point.position);
     IntPoint flooredPoint = flooredIntPoint(floatPos);
     m_pos = widget->convertFromContainingWindow(flooredPoint) + (floatPos - flooredPoint);
 
     m_screenPos = FloatPoint(point.screenPosition.x, point.screenPosition.y);
     m_radius = scaleSizeToWindow(widget, FloatSize(point.radiusX, point.radiusY));
     m_rotationAngle = point.rotationAngle;
     m_force = point.force;
+    // TODO(e_hakkinen): Leave only either tilt and tiltOrientation, tiltRad and
+    //                   tiltOrientationRad or tiltX and tiltY.
+    if (point.tilt) {

[mustaq, 2015/06/17 19:43:28]

Yes, representing the 3D tilt with two dedicated scalar angles is best solution
IMO, thanks. Since we can't really fix MotionEvent (as we discussed in
crrev.com/1147083005), we should fix the other relevant types in chromium
(WebTouchPoint & PlatformTouchPoint).

Among your 3 pairs of parameter names, I strongly prefer the last pair (tiltX &
tiltY) because these names are clearer in conveying the "3D-ness" of the
parameters, plus they would make it easier to rely on the PE spec for corner
cases.

Please use these names in both WebTouchPoint & PlatformTouchPoint, and move the
angle calculations below to CreateWebTouchPoint() in blink_event_util.cc (in
your other CL crrev.com/1187273004).

[USE eero AT chromium.org, 2015/06/18 11:34:08]

Done.

+        float tiltOrientationRad = point.tiltOrientation * M_PI / 180.f;
+        float tiltRad = point.tilt * M_PI / 180.f;
+        float r = sin(tiltRad);
+        float z = cos(tiltRad);
+        m_tilt = FloatPoint(
+            atan2(sin(tiltOrientationRad) * r, z) * 180.f / M_PI,
+            atan2(-cos(tiltOrientationRad) * r, z) * 180.f / M_PI);
+    } else {
+        m_tilt = FloatPoint(0, 0);
+    }
+    if (point.tiltRad) {
+        float r = sin(point.tiltRad);
+        float z = cos(point.tiltRad);
+        m_tilt = FloatPoint(
+            atan2(sin(point.tiltOrientationRad) * r, z) * 180.f / M_PI,
+            atan2(-cos(point.tiltOrientationRad) * r, z) * 180.f / M_PI);
+    } else {
+        m_tilt = FloatPoint(0, 0);
+    }
+    m_tilt = FloatPoint(point.tiltX, point.tiltY);
 }
 
 PlatformTouchEventBuilder::PlatformTouchEventBuilder(Widget* widget, const WebTouchEvent& event)
 {
     m_type = toPlatformTouchEventType(event.type);
     m_modifiers = toPlatformEventModifiers(event.modifiers);
     m_timestamp = event.timeStampSeconds;
     m_causesScrollingIfUncanceled = event.causesScrollingIfUncanceled;
 
     for (unsigned i = 0; i < event.touchesLength; ++i)
@@ skipping 310 matching lines @@
     modifiers = getWebInputModifiers(event);
 
     globalX = event.screenX();
     globalY = event.screenY();
     IntPoint localPoint = convertAbsoluteLocationForLayoutObject(event.absoluteLocation(), *layoutObject);
     x = localPoint.x();
     y = localPoint.y();
 }
 
 } // namespace blink