Add in gesture for immersive mode

ash/wm/window_properties.h

Index: ash/wm/window_properties.h
diff --git a/ash/wm/window_properties.h b/ash/wm/window_properties.h
index 21d7ae9e5dfedf7dbe12bf73b0c7cfbe2b0e116a..b34275a20330aab79658848f9e2b7ab9ea8349e7 100644
--- a/ash/wm/window_properties.h
+++ b/ash/wm/window_properties.h
@@ -54,6 +54,10 @@ ASH_EXPORT extern const aura::WindowProperty<bool>* const kImmersiveModeKey;
 // True if this window is an attached panel.
 ASH_EXPORT extern const aura::WindowProperty<bool>* const kPanelAttachedKey;
 
+// True if there is a pending immersive gesture occurance for this window.
+ASH_EXPORT extern const aura::WindowProperty<bool>* const
+    kPendingImmersiveGestureKey;
+
 // Used to remember the show state before the window was minimized.
 extern const aura::WindowProperty<ui::WindowShowState>* const
     kRestoreShowStateKey;