Fixed panel callout widgets showing up in the overview.

ash/wm/overview/window_selector_panels.h

Index: ash/wm/overview/window_selector_panels.h
diff --git a/ash/wm/overview/window_selector_panels.h b/ash/wm/overview/window_selector_panels.h
index 7d2131c4892b1d925ed5623d30e4dd4f00337190..b3ea49f61532a1ee974510a84e4c4e6c6dabfabb 100644
--- a/ash/wm/overview/window_selector_panels.h
+++ b/ash/wm/overview/window_selector_panels.h
@@ -20,7 +20,7 @@ class ScopedTransformOverviewWindow;
 // overview mode and the callout arrows are hidden at this point.
 class WindowSelectorPanels : public WindowSelectorItem {
  public:
-  WindowSelectorPanels();
+  explicit WindowSelectorPanels(aura::Window* panels_root_window);
   virtual ~WindowSelectorPanels();
 
   // Adds |window| to the selector item. This window should be an attached
@@ -44,6 +44,9 @@ class WindowSelectorPanels : public WindowSelectorItem {
   typedef ScopedVector<ScopedTransformOverviewWindow> WindowList;
   WindowList transform_windows_;
 
+  // The root window of the panels this item contains.
+  aura::Window* panels_root_window_;
+
   DISALLOW_COPY_AND_ASSIGN(WindowSelectorPanels);
 };