Removes WmRootWindowController subclasses

ash/aura/wm_lookup_aura.cc

Index: ash/aura/wm_lookup_aura.cc
diff --git a/ash/aura/wm_lookup_aura.cc b/ash/aura/wm_lookup_aura.cc
index b06822721e46eb73c3481168e183bf4450f524db..927723569087662bd490e587ff3c1ff39e13588b 100644
--- a/ash/aura/wm_lookup_aura.cc
+++ b/ash/aura/wm_lookup_aura.cc
@@ -4,11 +4,12 @@
 
 #include "ash/aura/wm_lookup_aura.h"
 
-#include "ash/aura/wm_root_window_controller_aura.h"
 #include "ash/aura/wm_window_aura.h"
 #include "ash/common/wm_layout_manager.h"
 #include "ash/display/window_tree_host_manager.h"
+#include "ash/root_window_controller.h"
 #include "ash/shell.h"
+#include "ui/views/widget/widget.h"
 
 namespace ash {
 
@@ -22,9 +23,13 @@ WmLookupAura::~WmLookupAura() {
 
 WmRootWindowController* WmLookupAura::GetRootWindowControllerWithDisplayId(
     int64_t id) {
-  return WmRootWindowControllerAura::Get(Shell::GetInstance()
-                                             ->window_tree_host_manager()
-                                             ->GetRootWindowForDisplayId(id));
+  aura::Window* root_window = Shell::GetInstance()
+                                  ->window_tree_host_manager()
+                                  ->GetRootWindowForDisplayId(id);
+  return root_window
+             ? RootWindowController::ForWindow(root_window)
+                   ->wm_root_window_controller()
+             : nullptr;
 }
 
 WmWindow* WmLookupAura::GetWindowForWidget(views::Widget* widget) {