Fix motion event orientation handling for styluses.

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 a6028fbdee52c3feb6394960f08ae0b563119270..685622c0c2511cebfbcc42937f680b06a2882fc9 100644
--- a/ui/events/gesture_detection/motion_event.h
+++ b/ui/events/gesture_detection/motion_event.h
@@ -93,7 +93,8 @@ class GESTURE_DETECTION_EXPORT MotionEvent {
   float GetTouchMinor() const { return GetTouchMinor(0); }
 
   // Returns the orientation of the major axis clockwise from vertical, in

[Rick Byers, 2015/05/26 20:21:33]

For stylus this isn't really returning "the orientation of the major axis",
right?  The Android definition is here:
http://developer.android.com/reference/android/view/MotionEvent.html#AXIS_ORI....
 I think we should have something similar in our comment - making it clear this
'orientation' is overloaded to mean two very different things depending on the
device type.

[USE eero AT chromium.org, 2015/05/27 08:39:39]

Done.

-  // radians. The return value lies in [-PI/2, PI/2].
+  // radians. The return value lies in [-PI, PI] (for a stylus) or in
+  // [-PI/2, PI/2] (for a touch screen or pad).
   float GetOrientation() const { return GetOrientation(0); }
 
   float GetPressure() const { return GetPressure(0); }