VR: Route hover and click events to UI elements.

chrome/browser/android/vr_shell/vr_shell_gl.h

Index: chrome/browser/android/vr_shell/vr_shell_gl.h
diff --git a/chrome/browser/android/vr_shell/vr_shell_gl.h b/chrome/browser/android/vr_shell/vr_shell_gl.h
index 8aa1406723c3562c3da92109401f7173de305c47..18c8ba1113ba55102c6863208fa1997205fd4ae0 100644
--- a/chrome/browser/android/vr_shell/vr_shell_gl.h
+++ b/chrome/browser/android/vr_shell/vr_shell_gl.h
@@ -134,9 +134,9 @@ class VrShellGl : public device::mojom::VRVSyncProvider {
   void HandleControllerInput(const gfx::Vector3dF& forward_vector);
   void HandleControllerAppButtonActivity(
       const gfx::Vector3dF& controller_direction);
-  void SendEventsToTarget(InputTarget input_target, int pixel_x, int pixel_y);
-  void SendGesture(InputTarget input_target,
-                   std::unique_ptr<blink::WebInputEvent> event);
+  void SendInputToContent(InputTarget input_target, int pixel_x, int pixel_y);
+  void SendInputToUiElements(UiElement* target_element);
+  void SendGestureToContent(std::unique_ptr<blink::WebInputEvent> event);
   void CreateUiSurface();
   void OnContentFrameAvailable();
   void OnWebVRFrameAvailable();
@@ -190,10 +190,17 @@ class VrShellGl : public device::mojom::VRVSyncProvider {
   vr::Quatf controller_quat_;
 
   gfx::Point3F target_point_;
-  const UiElement* target_element_ = nullptr;
+
+  // Input targeting for non-content elements.
+  UiElement* target_element_ = nullptr;
+  UiElement* previous_target_element_ = nullptr;
+  UiElement* click_target_element_ = nullptr;
+
+  // Input targeting for the content element.
   InputTarget current_input_target_ = InputTarget::NONE;
   InputTarget current_scroll_target_ = InputTarget::NONE;
   InputTarget current_fling_target_ = InputTarget::NONE;
+
   int content_tex_css_width_ = 0;
   int content_tex_css_height_ = 0;
   gfx::Size content_tex_physical_size_ = {0, 0};