Refactors StackingController::GetDefaultParent to ash/wm/common

ash/wm/common/container_finder.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ASH_WM_COMMON_CONTAINER_FINDER_H_
+#define ASH_WM_COMMON_CONTAINER_FINDER_H_
+
+#include "ash/wm/common/ash_wm_common_export.h"
+
+namespace gfx {
+class Rect;
+}
+
+namespace ash {
+namespace wm {
+
+class WmWindow;
+
+// Returns the first ancestor of |window| that has a known type.
+ASH_WM_COMMON_EXPORT WmWindow* GetContainerForWindow(WmWindow* window);
+
+// Returns the parent to add |window| to in |context|. This is generally
+// used when a window is moved from one root to another. In this case |context|
+// is the new root to add |window| to.
+ASH_WM_COMMON_EXPORT WmWindow* GetDefaultParent(WmWindow* context,
+                                                WmWindow* window,
+                                                const gfx::Rect& bounds);
+
+}  // namespace wm
+}  // namespace ash
+
+#endif  // ASH_WM_COMMON_CONTAINER_FINDER_H_