ash: Do not show the arrow in the tray bubbles when the tray isn't visible.

ash/wm/shelf_layout_manager.h

Index: ash/wm/shelf_layout_manager.h
diff --git a/ash/wm/shelf_layout_manager.h b/ash/wm/shelf_layout_manager.h
index f75de76bec7ae89abb6de0bf3310b218c1cf5453..fe38d57813af66b8505f8f065a39968d6761f0cd 100644
--- a/ash/wm/shelf_layout_manager.h
+++ b/ash/wm/shelf_layout_manager.h
@@ -87,6 +87,10 @@ class ASH_EXPORT ShelfLayoutManager : public aura::LayoutManager {
   // See description above field.
   int shelf_height() const { return shelf_height_; }
 
+  // Returns whether the shelf and its contents (launcher, status) are visible
+  // on the screen.
+  bool IsVisible() const;
+
   // Returns the bounds the specified window should be when maximized.
   gfx::Rect GetMaximizedWindowBounds(aura::Window* window) const;
   gfx::Rect GetUnmaximizedWorkAreaBounds(aura::Window* window) const;