Unify window fullscreen and minimizing implementation

ui/base/ui_base_types.h

Index: ui/base/ui_base_types.h
diff --git a/ui/base/ui_base_types.h b/ui/base/ui_base_types.h
index 4d29bb30d8c6f84dc424b273d6f025307140ec8b..2bb3e87e1d35d3ff3b9b526c03a124686a3df62e 100644
--- a/ui/base/ui_base_types.h
+++ b/ui/base/ui_base_types.h
@@ -21,7 +21,9 @@ enum WindowShowState {
   SHOW_STATE_INACTIVE   = 4,  // Views only, not persisted.
   SHOW_STATE_FULLSCREEN = 5,
   SHOW_STATE_DOCKED     = 6,
-  SHOW_STATE_END        = 7   // The end of show state enum.
+  SHOW_STATE_PREVIOUS   = 7,  // a temporary state for restoring the previous

[sky, 2017/01/18 16:48:16]

I would prefer not to expose this as a real state. It means everyone has to deal
with it, e.g.:
DCHECK_NE(show_state, ui::SHOW_STATE_PREVIOUS);

+                              // state from fullscreen and minized states.
+  SHOW_STATE_END        = 8   // The end of show state enum.
 };
 
 // Dialog button identifiers used to specify which buttons to show the user.