Folds WmRootWindowController into RootWindowController

ash/mus/bridge/wm_lookup_mus.cc

Index: ash/mus/bridge/wm_lookup_mus.cc
diff --git a/ash/mus/bridge/wm_lookup_mus.cc b/ash/mus/bridge/wm_lookup_mus.cc
index 8f96d88cdcebb6e348108fe37fc76f9b67fdfce4..b9b0be19a1704e38dd3a82b90279fd2e43185773 100644
--- a/ash/mus/bridge/wm_lookup_mus.cc
+++ b/ash/mus/bridge/wm_lookup_mus.cc
@@ -21,12 +21,11 @@ WmLookupMus::~WmLookupMus() {
     WmLookup::Set(nullptr);
 }
 
-WmRootWindowController* WmLookupMus::GetRootWindowControllerWithDisplayId(
+ash::RootWindowController* WmLookupMus::GetRootWindowControllerWithDisplayId(
     int64_t id) {
   return WmShellMus::Get()
       ->GetRootWindowControllerWithDisplayId(id)
-      ->ash_root_window_controller()
-      ->wm_root_window_controller();
+      ->ash_root_window_controller();
 }
 
 WmWindow* WmLookupMus::GetWindowForWidget(views::Widget* widget) {