Makes Panel related classes use ash/wm/common types

ash/wm/dock/docked_window_resizer_unittest.cc

Index: ash/wm/dock/docked_window_resizer_unittest.cc
diff --git a/ash/wm/dock/docked_window_resizer_unittest.cc b/ash/wm/dock/docked_window_resizer_unittest.cc
index f3f1761b90492a4f3fa5474cc7bb5ccf47120bd6..c24f2e48cd9f7517c53126c2b3138d7da1579681 100644
--- a/ash/wm/dock/docked_window_resizer_unittest.cc
+++ b/ash/wm/dock/docked_window_resizer_unittest.cc
@@ -83,9 +83,8 @@ class DockedWindowResizerTest
       test::TestShelfDelegate* shelf_delegate =
           test::TestShelfDelegate::instance();
       shelf_delegate->AddShelfItem(window);
-      PanelLayoutManager* manager = static_cast<PanelLayoutManager*>(
-          Shell::GetContainer(window->GetRootWindow(),
-                              kShellWindowId_PanelContainer)->layout_manager());
+      PanelLayoutManager* manager =
+          PanelLayoutManager::Get(wm::WmWindowAura::Get(window));
       manager->Relayout();
     }
     return window;