Add LockLayoutManager responsible for lock container (login/lock).

ash/ash_switches.cc

Index: ash/ash_switches.cc
diff --git a/ash/ash_switches.cc b/ash/ash_switches.cc
index 75af4147bbd3783b55b02a725e88189e2ba000fc..48b0e93673def995699b59941f3b5fbc92d8899d 100644
--- a/ash/ash_switches.cc
+++ b/ash/ash_switches.cc
@@ -38,6 +38,10 @@ const char kAshDefaultWallpaperIsOem[] = "ash-default-wallpaper-is-oem";
 const char kAshDefaultWallpaperLarge[] = "ash-default-wallpaper-large";
 const char kAshDefaultWallpaperSmall[] = "ash-default-wallpaper-small";
 
+// Disables LockLayoutManager used for LockScreenContainer, return back to
+// WorkspaceLayoutManager.
+const char kAshDisableLockLayoutManager[] = "ash-disable-lock-layout-manager";
+
 // Disable the Touch Exploration Mode. Touch Exploration Mode will no longer be
 // turned on automatically when spoken feedback is enabled when this flag is
 // set.