Fix tests in when MD is set to EXPERIMENTAL by default

chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc

Index: chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
diff --git a/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc b/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
index a03a3816582a55cad43661f9f2ef8df951b86dce..ca57f1d0a1b4e8931790cbfc9cb74560ce5ac4d8 100644
--- a/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
+++ b/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
@@ -247,6 +247,8 @@ void BrowserNonClientFrameViewAsh::ResetWindowControls() {
   // Hide the caption buttons in immersive fullscreen when the tab light bar
   // is visible because it's confusing when the user hovers or clicks in the
   // top-right of the screen and hits one.
+  // TODO(yiyix): Update |caption_button_container_|'s visibility calculation
+  // when Chrome OS MD is enabled by default.
   caption_button_container_->SetVisible(!UseImmersiveLightbarHeaderStyle());
   caption_button_container_->ResetWindowControls();
 }