Remove WmLookup.

ash/common/wm/panels/panel_window_resizer.cc

Index: ash/common/wm/panels/panel_window_resizer.cc
diff --git a/ash/common/wm/panels/panel_window_resizer.cc b/ash/common/wm/panels/panel_window_resizer.cc
index 9a8aa83511c11db0533e688b3dd24e15c0419d01..2a18c81b47e11a5300b1db6058f1f9e261134b2f 100644
--- a/ash/common/wm/panels/panel_window_resizer.cc
+++ b/ash/common/wm/panels/panel_window_resizer.cc
@@ -8,11 +8,11 @@
 #include "ash/common/wm/panels/panel_layout_manager.h"
 #include "ash/common/wm/window_parenting_utils.h"
 #include "ash/common/wm/window_state.h"
-#include "ash/common/wm_lookup.h"
 #include "ash/common/wm_window.h"
 #include "ash/common/wm_window_property.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/root_window_controller.h"
+#include "ash/shell.h"
 #include "ui/base/hit_test.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/display/display.h"
@@ -56,8 +56,7 @@ void PanelWindowResizer::Drag(const gfx::Point& location, int event_flags) {
     if (GetTarget()->GetParent() != panel_container_)
       PanelLayoutManager::Get(panel_container_)->FinishDragging();
     WmWindow* dst_root =
-        WmLookup::Get()
-            ->GetRootWindowControllerWithDisplayId(dst_display.id())
+        Shell::GetRootWindowControllerWithDisplayId(dst_display.id())
             ->GetWindow();
     panel_container_ =
         dst_root->GetChildByShellWindowId(kShellWindowId_PanelContainer);