Update the layout mode first when exiting tablet mode

ash/common/wm_shell.h

Index: ash/common/wm_shell.h
diff --git a/ash/common/wm_shell.h b/ash/common/wm_shell.h
index ce82fd4b70d7ea3cd2d239f156353e52ddc92afb..528a61cb65d95c31693cf8933adef693a7136026 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -368,6 +368,9 @@ class ASH_EXPORT WmShell : public SessionStateObserver,
   // Called after maximize mode has started, windows might still animate though.
   void OnMaximizeModeStarted();
 
+  // Called after maximize mode is about to end.
+  void OnMaximizeModeEnding();
+
   // Called after maximize mode has ended, windows might still be returning to
   // their original position.
   void OnMaximizeModeEnded();