Refactors StackingController::GetDefaultParent to ash/wm/common

ash/wm/common/wm_shell_window_ids.h

Index: ash/wm/common/wm_shell_window_ids.h
diff --git a/ash/wm/common/wm_shell_window_ids.h b/ash/wm/common/wm_shell_window_ids.h
index 803750e6d700f3d6535089832515ad1705ee2ad9..4c6ed096c89922c518eb3162145f94f4c71ad772 100644
--- a/ash/wm/common/wm_shell_window_ids.h
+++ b/ash/wm/common/wm_shell_window_ids.h
@@ -14,6 +14,10 @@ namespace ash {
 // NOTE: while the value of these is not necessarily important, the ordering
 // is and is enforced in ash/shell_window_ids.h.
 
+// A container used for windows of WINDOW_TYPE_CONTROL that have no parent.
+// This container is not visible.
+const int kShellWindowId_UnparentedControlContainer = 3;
+
 // The container for standard top-level windows.
 const int kShellWindowId_DefaultContainer = 6;
 
@@ -33,6 +37,21 @@ const int kShellWindowId_PanelContainer = 11;
 // The container for the app list.
 const int kShellWindowId_AppListContainer = 12;
 
+// The container for user-specific modal windows.
+const int kShellWindowId_SystemModalContainer = 13;
+
+// The container for the lock screen.
+const int kShellWindowId_LockScreenContainer = 15;
+
+// The container for the lock screen modal windows.
+const int kShellWindowId_LockSystemModalContainer = 16;
+
+// The container for menus.
+const int kShellWindowId_MenuContainer = 19;
+
+// The container for drag/drop images and tooltips.
+const int kShellWindowId_DragImageAndTooltipContainer = 20;
+
 // ID of the window created by PhantomWindowController or DragWindowController.
 const int kShellWindowId_PhantomWindow = 23;