Fix an interactive ui test

ui/aura/test/ui_controls_factory_ozone.cc

Index: ui/aura/test/ui_controls_factory_ozone.cc
diff --git a/ui/aura/test/ui_controls_factory_ozone.cc b/ui/aura/test/ui_controls_factory_ozone.cc
index 403757b947503c7c2cf344760960eb90af5a6937..b34783a314681e1bbb924d1523c949441933525c 100644
--- a/ui/aura/test/ui_controls_factory_ozone.cc
+++ b/ui/aura/test/ui_controls_factory_ozone.cc
@@ -21,6 +21,9 @@ namespace aura {
 namespace test {
 namespace {
 
+// Mask of the mouse buttons currently down.
+unsigned button_down_mask_ = 0;
+
 class UIControlsOzone : public ui_controls::UIControlsAura {
  public:
   UIControlsOzone(WindowTreeHost* host) : host_(host) {}
@@ -229,9 +232,6 @@ class UIControlsOzone : public ui_controls::UIControlsAura {
 
   WindowTreeHost* host_;
 
-  // Mask of the mouse buttons currently down.
-  unsigned button_down_mask_ = 0;
-
   DISALLOW_COPY_AND_ASSIGN(UIControlsOzone);
 };