Aura: Add --aura-laptop-mode to fill the workspace with a single window.

ui/aura_shell/shell.h

Index: ui/aura_shell/shell.h
diff --git a/ui/aura_shell/shell.h b/ui/aura_shell/shell.h
index 80f5060a402638557873d954c856ef22ef841a41..662f793c0c09853c320bb2470921c1ed193d4a9b 100644
--- a/ui/aura_shell/shell.h
+++ b/ui/aura_shell/shell.h
@@ -18,6 +18,7 @@
 
 namespace aura {
 class EventFilter;
+class RootWindow;
 class Window;
 }
 namespace gfx {
@@ -81,6 +82,8 @@ class AURA_SHELL_EXPORT Shell {
   }
 
   ShellDelegate* delegate() { return delegate_.get(); }
+
+  // May return NULL if we're not using a launcher (e.g. laptop-mode).
   Launcher* launcher() { return launcher_.get(); }
 
   // Made available for tests.
@@ -95,6 +98,7 @@ class AURA_SHELL_EXPORT Shell {
   virtual ~Shell();
 
   void Init();
+  void InitLayoutManagers(aura::RootWindow* root_window);
 
   // Enables WorkspaceManager.
   void EnableWorkspaceManager();