Detach SystemMediaControls from Window::Controller.

Telegram/SourceFiles/mainwidget.h

@@ -233,7 +233,6 @@ public:
 
 	using FloatDelegate::floatPlayerAreaUpdated;
 
-	void closeBothPlayers();
 	void stopAndClosePlayer();
 
 	bool preventsCloseSection(Fn<void()> callback) const;
@@ -302,6 +301,8 @@ private:
 	void hiderLayer(base::unique_qptr<Window::HistoryHider> h);
 	void clearHider(not_null<Window::HistoryHider*> instance);
 
+	void closeBothPlayers();
+
 	[[nodiscard]] auto floatPlayerDelegate()
 		-> not_null<Media::Player::FloatDelegate*>;
 	not_null<Ui::RpWidget*> floatPlayerWidget() override;