Fix the full screen switching browser window dipping below launcher bar issue.

ui/aura/root_window_observer.h

Index: ui/aura/root_window_observer.h
diff --git a/ui/aura/root_window_observer.h b/ui/aura/root_window_observer.h
index 8df353e4cacbd166617d6350935b16f47d546e7f..930790df396e53aa931e43588274fecdae493438 100644
--- a/ui/aura/root_window_observer.h
+++ b/ui/aura/root_window_observer.h
@@ -21,6 +21,9 @@ class AURA_EXPORT RootWindowObserver {
   // Invoked after the RootWindow is resized.
   virtual void OnRootWindowResized(const gfx::Size& new_size) {}
 
+  // Invoked after the screen's work area insets changes.
+  virtual void OnScreenWorkAreaInsetsChanged() {}
+
   // Invoked when a window is focused.
   virtual void OnWindowFocused(Window* window) {}