Fixing invalid window opacity/visibility combination with the shelf

ash/shelf/shelf_layout_manager.cc

Index: ash/shelf/shelf_layout_manager.cc
diff --git a/ash/shelf/shelf_layout_manager.cc b/ash/shelf/shelf_layout_manager.cc
index 9df4bdc791d25f11f9376ac5e6bf0b96c04ba687..db8c6ea11303ebeffc6c0dd4dd5743880dccace3 100644
--- a/ash/shelf/shelf_layout_manager.cc
+++ b/ash/shelf/shelf_layout_manager.cc
@@ -723,6 +723,14 @@ void ShelfLayoutManager::UpdateBoundsAndOpacity(
 
   GetLayer(shelf_->status_area_widget())->SetOpacity(
       target_bounds.status_opacity);
+
+  // Having a window which is visible but does not have an opacity is an illegal
+  // state. We therefore show / hide the shelf here if required.
+  if (!target_bounds.status_opacity)
+    shelf_->status_area_widget()->Hide();
+  else if (target_bounds.status_opacity)
+    shelf_->status_area_widget()->Show();
+
   // TODO(harrym): Once status area widget is a child view of shelf
   // this can be simplified.
   gfx::Rect status_bounds = target_bounds.status_bounds_in_shelf;