Explicitly coerce PostDispatchAction to uint32_t in DispatchEvent()

ui/wm/core/nested_accelerator_dispatcher_linux.cc

Index: ui/wm/core/nested_accelerator_dispatcher_linux.cc
diff --git a/ui/wm/core/nested_accelerator_dispatcher_linux.cc b/ui/wm/core/nested_accelerator_dispatcher_linux.cc
index ee5b587225cf6149e8bbe5b0301a911240102e4e..16a4efb8a29b05bdfd4899f8273b7b6b14f8171e 100644
--- a/ui/wm/core/nested_accelerator_dispatcher_linux.cc
+++ b/ui/wm/core/nested_accelerator_dispatcher_linux.cc
@@ -85,8 +85,8 @@ class NestedAcceleratorDispatcherLinux : public NestedAcceleratorDispatcher,
     }
     ui::PlatformEventDispatcher* prev = *restore_dispatcher_;
 
-    return prev ? prev->DispatchEvent(event)
-                : ui::POST_DISPATCH_PERFORM_DEFAULT;
+    uint32_t perform_default = ui::POST_DISPATCH_PERFORM_DEFAULT;
+    return prev ? prev->DispatchEvent(event) : perform_default;
   }
 
   scoped_ptr<ui::ScopedEventDispatcher> restore_dispatcher_;