VR: Route hover and click events to UI elements.

chrome/browser/android/vr_shell/ui_elements/ui_element.h

Index: chrome/browser/android/vr_shell/ui_elements/ui_element.h
diff --git a/chrome/browser/android/vr_shell/ui_elements/ui_element.h b/chrome/browser/android/vr_shell/ui_elements/ui_element.h
index 39acace488cbeb9f55fa27eaaf6b686440293de7..5d1d6eea36d9b1c9615f948808b45c0c38d7c9eb 100644
--- a/chrome/browser/android/vr_shell/ui_elements/ui_element.h
+++ b/chrome/browser/android/vr_shell/ui_elements/ui_element.h
@@ -104,6 +104,12 @@ struct UiElement : public WorldRectangle {
 
   virtual void Initialize();
 
+  // Controller interaction methods.
+  virtual void OnHoverEnter();
+  virtual void OnHoverLeave();
+  virtual void OnButtonDown();
+  virtual void OnButtonUp();
+
   // Valid IDs are non-negative.
   int id = -1;