[vr] Add incognito coloring

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

Index: chrome/browser/android/vr_shell/ui_elements/ui_element.cc
diff --git a/chrome/browser/android/vr_shell/ui_elements/ui_element.cc b/chrome/browser/android/vr_shell/ui_elements/ui_element.cc
index d48861dc9d26ec7751525bcd71d25302f03b8238..15fc6e26883d407802954b020c11754d9582dbae 100644
--- a/chrome/browser/android/vr_shell/ui_elements/ui_element.cc
+++ b/chrome/browser/android/vr_shell/ui_elements/ui_element.cc
@@ -231,4 +231,13 @@ bool UiElement::HitTest(const gfx::PointF& point) const {
          point.y() <= 1.0f;
 }
 
+void UiElement::SetMode(ColorScheme::Mode mode) {
+  if (mode_ == mode)
+    return;
+  mode_ = mode;
+  OnSetMode();
+}
+
+void UiElement::OnSetMode() {}
+
 }  // namespace vr_shell