Fixed ui::TouchEvent rotation angle out-of-bound issue.

ui/events/gestures/motion_event_aura.cc

Index: ui/events/gestures/motion_event_aura.cc
diff --git a/ui/events/gestures/motion_event_aura.cc b/ui/events/gestures/motion_event_aura.cc
index 1f4d2855b2fc0cfc5d3cd32495f5586d6f6cea13..0f2aca912c0fe34e302386583967ae37cf8481ba 100644
--- a/ui/events/gestures/motion_event_aura.cc
+++ b/ui/events/gestures/motion_event_aura.cc
@@ -28,11 +28,19 @@ PointerProperties GetPointerPropertiesFromTouchEvent(const TouchEvent& touch) {
   float radius_x = touch.radius_x();
   float radius_y = touch.radius_y();
   float rotation_angle_rad = touch.rotation_angle() * M_PI / 180.f;
+
   DCHECK_GE(radius_x, 0) << "Unexpected x-radius < 0";
   DCHECK_GE(radius_y, 0) << "Unexpected y-radius < 0";
-  DCHECK(0 <= rotation_angle_rad && rotation_angle_rad <= M_PI_2)
+  DCHECK(0 <= rotation_angle_rad && rotation_angle_rad < M_PI)
       << "Unexpected touch rotation angle";
 
+  // Make the angle acute to ease subsequent logic. The angle range effectively
+  // changes from [0, pi) to [0, pi/2).

[tdresser, 2015/01/20 16:40:38]

Wouldn't hurt to have a test for this logic.

[mustaq, 2015/01/21 16:43:10]

Done.

+  if (rotation_angle_rad >= M_PI_2) {
+    rotation_angle_rad -= M_PI_2;
+    std::swap(radius_x, radius_y);
+  }
+
   if (radius_x > radius_y) {
     // The case radius_x == radius_y is omitted from here on purpose: for
     // circles, we want to pass the angle (which could be any value in such