aura: Draw drop shadows under browsers and menus.

ui/aura/client/shadow_types.h

Index: ui/aura/client/shadow_types.h
diff --git a/ui/aura/client/shadow_types.h b/ui/aura/client/shadow_types.h
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+// Copyright (c) 2011 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 UI_AURA_CLIENT_SHADOW_TYPES_H_
+#define UI_AURA_CLIENT_SHADOW_TYPES_H_
+#pragma once
+
+namespace aura {
+
+// Different types of drop shadows that can be drawn under a window by the
+// shell.  Used as a value for the kShadowTypeKey property.
+enum AURA_EXPORT ShadowType {
+  SHADOW_TYPE_NONE = 0,
+  SHADOW_TYPE_RECTANGULAR,
+};
+
+}  // namespace aura
+
+#endif  // UI_AURA_CLIENT_SHADOW_TYPES_H_