Separate ash::test::DisplayManagerTestApi from ash

ash/wm/panels/panel_layout_manager_unittest.cc

Index: ash/wm/panels/panel_layout_manager_unittest.cc
diff --git a/ash/wm/panels/panel_layout_manager_unittest.cc b/ash/wm/panels/panel_layout_manager_unittest.cc
index 8bd84d0936a30a9442081d6c5b4dd8e3d8a4163d..d7f2b4e931080805ca976fd9a60d62573916a642 100644
--- a/ash/wm/panels/panel_layout_manager_unittest.cc
+++ b/ash/wm/panels/panel_layout_manager_unittest.cc
@@ -313,7 +313,8 @@ TEST_F(PanelLayoutManagerTest, UndockTest) {
   std::vector<display::ManagedDisplayInfo> info_list;
 
   const int64_t internal_display_id =
-      test::DisplayManagerTestApi().SetFirstDisplayAsInternalDisplay();
+      test::DisplayManagerTestApi(Shell::GetInstance()->display_manager())
+          .SetFirstDisplayAsInternalDisplay();
 
   // Create the primary display info.
   display::ManagedDisplayInfo internal_display =
@@ -343,7 +344,8 @@ TEST_F(PanelLayoutManagerTest, DockUndockTest) {
   std::vector<display::ManagedDisplayInfo> info_list;
 
   const int64_t internal_display_id =
-      test::DisplayManagerTestApi().SetFirstDisplayAsInternalDisplay();
+      test::DisplayManagerTestApi(Shell::GetInstance()->display_manager())
+          .SetFirstDisplayAsInternalDisplay();
 
   // Create the primary display info.
   display::ManagedDisplayInfo internal_display =