Positions the launcher in the bottom left corner. Adds ShellDelegate

ui/aura/desktop.h

Index: ui/aura/desktop.h
diff --git a/ui/aura/desktop.h b/ui/aura/desktop.h
index 521876a273e99f7a1d353e75d33d505681d616d6..55963e36de7f7c153f65d779c736809bd0e5bcec 100644
--- a/ui/aura/desktop.h
+++ b/ui/aura/desktop.h
@@ -94,6 +94,12 @@ class AURA_EXPORT Desktop : public ui::CompositorDelegate {
   // Invoked from RootWindow when |window| is being destroyed.
   void WindowDestroying(Window* window);
 
+  // Invoked when a window is added.
+  void WindowAdded(Window* window);
+
+  // Invoked when a window is removed.
+  void WillRemoveWindow(Window* window);
+
   // Returns the desktop's dispatcher. The result should only be passed to
   // MessageLoopForUI::Run() or MessageLoopForUI::RunAllPendingWithDispatcher(),
   // or used to dispatch an event by |Dispatch(const NativeEvent&)| on it.