Layout panels on top of their launcher icons

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index fbf81b6b195e8f3da9d2694512c3a4b3b64572a7..1daf7299191770830e7b8c32247cb1eebc1f98b9 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -66,6 +66,7 @@ class FocusCycler;
 class InputMethodEventFilter;
 class KeyRewriterEventFilter;
 class MonitorController;
+class PanelLayoutManager;
 class PartialScreenshotEventFilter;
 class ResizeShadowController;
 class RootWindowEventFilter;
@@ -323,6 +324,9 @@ class ASH_EXPORT Shell {
   // the status area.
   internal::ShelfLayoutManager* shelf_;
 
+  // Manages layout of panels. Owned by container of panels.
+  internal::PanelLayoutManager* panel_layout_manager_;
+
   ObserverList<ShellObserver> observers_;
 
   // Owned by aura::RootWindow, cached here for type safety.