Change mojo enums to be scoped enums in the generated C++ bindings.

mash/wm/property_util.h

Index: mash/wm/property_util.h
diff --git a/mash/wm/property_util.h b/mash/wm/property_util.h
index 04b540a2463c5547811f43bad38d741d18e80abd..54b21c7f2d9b1600791a59d0a6450053b4316ad8 100644
--- a/mash/wm/property_util.h
+++ b/mash/wm/property_util.h
@@ -37,7 +37,9 @@ gfx::Size GetWindowPreferredSize(const mus::Window* window);
 
 mojom::Container GetRequestedContainer(const mus::Window* window);
 
-mus::mojom::ResizeBehavior GetResizeBehavior(const mus::Window* window);
+// Returns a bitfield of kResizeBehavior* values from
+// window_manager_constants.mojom.
+int32_t GetResizeBehavior(const mus::Window* window);
 
 void SetRestoreBounds(mus::Window* window, const gfx::Rect& bounds);
 gfx::Rect GetRestoreBounds(const mus::Window* window);