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 2c0657be4a48ab3b79aaa8e097f893f81c1f7bf3..d10310594da87de039386b8e33b2fedfb444d505 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;
@@ -331,6 +332,9 @@ class ASH_EXPORT Shell {
   // the status area.
   internal::ShelfLayoutManager* shelf_;
 
+  // Manages layout of panels. Owned by PanelContainer.
+  internal::PanelLayoutManager* panel_layout_manager_;
+
   ObserverList<ShellObserver> observers_;
 
   // Owned by aura::RootWindow, cached here for type safety.