Show overview mode button in TouchView with open modal window

ash/wm/overview/window_selector_controller.h

Index: ash/wm/overview/window_selector_controller.h
diff --git a/ash/wm/overview/window_selector_controller.h b/ash/wm/overview/window_selector_controller.h
index 8d4a625e13e72ec9aab2c160e03e59900d2648f6..be35f154a0586343ea23c46bcde061d66b88454b 100644
--- a/ash/wm/overview/window_selector_controller.h
+++ b/ash/wm/overview/window_selector_controller.h
@@ -32,8 +32,14 @@ class ASH_EXPORT WindowSelectorController
   WindowSelectorController();
   ~WindowSelectorController() override;
 
-  // Returns true if selecting windows in an overview is enabled. This is false
-  // at certain times, such as when the lock screen is visible.
+  // Returns true if the user is in an active desktop environment, i.e., they
+  // are logged in, the screen is not locked, and they are not running in
+  // kiosk mode.
+  static bool IsUserInActiveDesktopEnvironment();
+
+  // Returns true if the user is permitted to engage overview mode (the user
+  // must be in an active desktop environment and must not have any modal
+  // windows open).
   static bool CanSelect();
 
   // Enters overview mode. This is essentially the window cycling mode however