Exempt status bubble windows from status bar darkening

ash/wm/property_util.cc

Index: ash/wm/property_util.cc
diff --git a/ash/wm/property_util.cc b/ash/wm/property_util.cc
index 0163b2d4bbd856cc9634dc9e59089724eda9b1a7..d52b196bd39548822004ed2941072ca13a52b047 100644
--- a/ash/wm/property_util.cc
+++ b/ash/wm/property_util.cc
@@ -52,6 +52,14 @@ bool GetTrackedByWorkspace(aura::Window* window) {
   return window->GetProperty(internal::kWindowTrackedByWorkspaceKey);
 }
 
+void SetIgnoredByShelf(aura::Window* window, bool value) {
+  window->SetProperty(internal::kIgnoredByShelfKey, value);
+}
+
+bool GetIgnoredByShelf(aura::Window* window) {
+  return window->GetProperty(internal::kIgnoredByShelfKey);
+}
+
 void SetPersistsAcrossAllWorkspaces(
     aura::Window* window,
     WindowPersistsAcrossAllWorkspacesType type) {