cros: Remove TODO in ash::SystemTrayController

It suggested some renaming that I'm not sure is a good idea anymore.

TBR=stevenjb@chromium.org

Bug: none
Change-Id: Icceb6281b3962f7d99b6370ed37a3a51efebf615
Reviewed-on: https://chromium-review.googlesource.com/934637Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#538809}

ash/system/tray/system_tray_controller.h

@@ -18,9 +18,6 @@ namespace ash {
 // interface. Implements both because it caches state pushed down from the
 // browser process via SystemTray so it can be synchronously queried inside ash.
 // Lives on the main thread.
-//
-// TODO: Consider renaming this to SystemTrayClient or renaming the current
-// SystemTray to SystemTrayView and making this class SystemTray.
 class ASH_EXPORT SystemTrayController : public mojom::SystemTray {
  public:
   SystemTrayController();