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

ui/aura/root_window.cc

Index: ui/aura/root_window.cc
diff --git a/ui/aura/root_window.cc b/ui/aura/root_window.cc
index e4119826e7048823ab6f4d5dc5f52c8119bc6e05..97eb38b99770aa368c451565c2ec8cf369097349 100644
--- a/ui/aura/root_window.cc
+++ b/ui/aura/root_window.cc
@@ -278,6 +278,11 @@ bool RootWindow::DispatchGestureEvent(GestureEvent* event) {
   return false;
 }
 
+void RootWindow::OnScreenWorkAreaInsetsChanged() {
+  FOR_EACH_OBSERVER(RootWindowObserver, observers_,
+                    OnScreenWorkAreaInsetsChanged());
+}
+
 void RootWindow::OnHostResized(const gfx::Size& size) {
   // The compositor should have the same size as the native root window host.
   compositor_->WidgetSizeChanged(size);