Use MD-ash's auto hide behavior for arc++ windows.

chrome/browser/ui/views/frame/immersive_mode_controller_ash.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/frame/immersive_mode_controller_ash.h"
 
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/wm/immersive_revealed_lock.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/shell.h"
@@ skipping 248 matching lines @@
     return;
 
   bool tab_indicator_visibility_changed = UpdateTabIndicators();
 
   // Auto hide the shelf in immersive browser fullscreen. When auto hidden and
   // Material Design is not enabled, the shelf displays a 3px 'light bar' when
   // it is closed. When in immersive browser fullscreen and tab fullscreen, hide
   // the shelf completely and prevent it from being revealed.
   bool in_tab_fullscreen = content::Source<FullscreenController>(source)->
       IsWindowFullscreenForTabOrPending();
-  ash::wm::GetWindowState(native_window_)->set_hide_shelf_when_fullscreen(
-      in_tab_fullscreen);
+  ash::wm::GetWindowState(native_window_)
+      ->set_shelf_mode_in_fullscreen(
+          in_tab_fullscreen ? ash::wm::WindowState::SHELF_HIDDEN
+                            : ash::wm::WindowState::SHELF_AUTO_HIDE_VISIBLE);
   ash::Shell::GetInstance()->UpdateShelfVisibility();
 
   if (tab_indicator_visibility_changed)
     LayoutBrowserRootView();
 }