Positions the launcher in the bottom left corner. Adds ShellDelegate

ui/aura/desktop_delegate.h

Index: ui/aura/desktop_delegate.h
diff --git a/ui/aura/desktop_delegate.h b/ui/aura/desktop_delegate.h
index 5438533e92572115e3d49354b7dc258c02635163..c09a6978f33a5d02e86a48dbc5ea3fdaee573cba 100644
--- a/ui/aura/desktop_delegate.h
+++ b/ui/aura/desktop_delegate.h
@@ -23,6 +23,14 @@ class AURA_EXPORT DesktopDelegate {
 
   // Returns the window that should be activated other than |ignore|.
   virtual Window* GetTopmostWindowToActivate(Window* ignore) const = 0;
+
+  // TODO(sky): convert these to DesktopObserver methods once Sadrul lands his
+  // patch.
+  // Invoked when a window is added.
+  virtual void WindowAdded(Window* window) = 0;
+
+  // Invoked before a window is removed.
+  virtual void WillRemoveWindow(Window* window) = 0;
 };
 
 }  // namespace aura