Update the layout mode first when exiting tablet mode

ash/common/wm_shell.cc

Index: ash/common/wm_shell.cc
diff --git a/ash/common/wm_shell.cc b/ash/common/wm_shell.cc
index 4aa11831fd0299d22ce937f5e582aae555d90bc8..fcd7804aad242e9f61489c6f20e761ce8871bae5 100644
--- a/ash/common/wm_shell.cc
+++ b/ash/common/wm_shell.cc
@@ -182,6 +182,11 @@ void WmShell::OnMaximizeModeStarted() {
     observer.OnMaximizeModeStarted();
 }
 
+void WmShell::OnMaximizeModeEnding() {
+  for (auto& observer : shell_observers_)
+    observer.OnMaximizeModeEnding();
+}
+
 void WmShell::OnMaximizeModeEnded() {
   for (auto& observer : shell_observers_)
     observer.OnMaximizeModeEnded();