PROTOTYPE (incomplete): Add quad renderer and stub bits to handle security warnings.

chrome/browser/android/vr_shell/ui_element.cc

Index: chrome/browser/android/vr_shell/ui_element.cc
diff --git a/chrome/browser/android/vr_shell/ui_element.cc b/chrome/browser/android/vr_shell/ui_element.cc
index 8b8c25a3e58d9e1aad8e6d7e08f7df8f22cc9901..cf5f0bc880cb78d11e940c4c470cd9e482257109 100644
--- a/chrome/browser/android/vr_shell/ui_element.cc
+++ b/chrome/browser/android/vr_shell/ui_element.cc
@@ -105,6 +105,10 @@ UiElement::UiElement() = default;
 
 UiElement::~UiElement() = default;
 
+bool UiElement::Render(VrShellRenderer* renderer) const {
+  return false;
+}
+
 void UiElement::Animate(const base::TimeTicks& time) {
   for (auto& it : animations) {
     Animation& animation = *it;