[Docking] Persists docked state on Chrome OS

ash/wm/window_state.cc

Index: ash/wm/window_state.cc
diff --git a/ash/wm/window_state.cc b/ash/wm/window_state.cc
index ffe25f3c7f1e88e65572243c0aa14143aa89495d..94335cc0f02c526c17980cdc7272b46a82238d8c 100644
--- a/ash/wm/window_state.cc
+++ b/ash/wm/window_state.cc
@@ -71,6 +71,8 @@ WMEventType WMEventTypeFromShowState(ui::WindowShowState requested_show_state) {
       return WM_EVENT_FULLSCREEN;
     case ui::SHOW_STATE_INACTIVE:
       return WM_EVENT_SHOW_INACTIVE;
+    case ui::SHOW_STATE_DOCKED:
+      return WM_EVENT_DOCK;
     case ui::SHOW_STATE_END:
       NOTREACHED() << "No WMEvent defined for the show state:"
                    << requested_show_state;