Validate incoming window properties.

ui/wm/core/shadow_types.h

Index: ui/wm/core/shadow_types.h
diff --git a/ui/wm/core/shadow_types.h b/ui/wm/core/shadow_types.h
index ef22af7adf394e4184149157a9fd2b4edab9ff5a..91ba36dec07a5cd50850e6297f863845403717b1 100644
--- a/ui/wm/core/shadow_types.h
+++ b/ui/wm/core/shadow_types.h
@@ -5,6 +5,7 @@
 #ifndef UI_WM_CORE_SHADOW_TYPES_H_
 #define UI_WM_CORE_SHADOW_TYPES_H_
 
+#include "base/callback_forward.h"
 #include "ui/aura/window.h"
 #include "ui/wm/wm_export.h"
 
@@ -30,6 +31,10 @@ enum class ShadowElevation {
 WM_EXPORT void SetShadowElevation(aura::Window* window,
                                   ShadowElevation elevation);
 
+// Returns a callback which will return true if the value passed to it is a
+// valid ShadowElevation value.
+WM_EXPORT base::RepeatingCallback<bool(int32_t)> ValidateShadowElevation();

[sky, 2017/02/23 21:02:25]

Similar comment about exposing a function, not a callback.

[Elliot Glaysher, 2017/02/23 22:12:43]

Done.

+
 // A property key describing the drop shadow that should be displayed under the
 // window. A null value is interpreted as using the default.
 WM_EXPORT extern const aura::WindowProperty<ShadowElevation>* const