Remove unnecessary UI element math.

chrome/browser/android/vr_shell/ui_elements.h

Index: chrome/browser/android/vr_shell/ui_elements.h
diff --git a/chrome/browser/android/vr_shell/ui_elements.h b/chrome/browser/android/vr_shell/ui_elements.h
index ec6d78a0f93bcecc35efc457764660aca2e877ab..17adc48167305c5716b71c8d77136c464804e35f 100644
--- a/chrome/browser/android/vr_shell/ui_elements.h
+++ b/chrome/browser/android/vr_shell/ui_elements.h
@@ -44,8 +44,8 @@ enum Fill {
   CONTENT = 4,
 };
 
-struct ReversibleTransform {
-  ReversibleTransform();
+struct Transform {
+  Transform();
 
   void MakeIdentity();
   void Rotate(gvr::Quatf quat);
@@ -54,23 +54,22 @@ struct ReversibleTransform {
   void Scale(float sx, float sy, float sz);
 
   gvr::Mat4f to_world;
-  gvr::Mat4f from_world;
-
-  // This object-to-world orientation quaternion is technically
-  // redundant, but it's easy to track it here for use as needed.
-  // TODO(klausw): use this instead of MatrixVectorRotation()?
-  // Would need quat * vector implementation.
-  gvr::Quatf orientation = {0.0f, 0.0f, 0.0f, 1.0f};
 };
 
-struct WorldObject {
-  ReversibleTransform transform;
-};
+class WorldRectangle {
+ public:
+  const gvr::Mat4f& TransformMatrix() const;
+  void SetTransform(const Transform& transform);
 
-struct WorldRectangle : public WorldObject {
   gvr::Vec3f GetCenter() const;
   gvr::Vec3f GetNormal() const;
-  float GetRayDistance(gvr::Vec3f rayOrigin, gvr::Vec3f rayVector) const;
+  bool GetRayDistance(const gvr::Vec3f& ray_origin,
+                      const gvr::Vec3f& ray_vector,
+                      float* distance) const;
+  gvr::Vec2f GetUnitRectangleCoordinates(const gvr::Vec3f& world_point);
+
+ private:
+  Transform transform_;
 };
 
 struct ContentRectangle : public WorldRectangle {