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

ash/wm/immersive_fullscreen_controller.cc

Index: ash/wm/immersive_fullscreen_controller.cc
diff --git a/ash/wm/immersive_fullscreen_controller.cc b/ash/wm/immersive_fullscreen_controller.cc
index 13ce2d36ba06a27108a86b71205329a6dcb5def7..8a2fa5c9f54f275f924b74df3de802b858231e33 100644
--- a/ash/wm/immersive_fullscreen_controller.cc
+++ b/ash/wm/immersive_fullscreen_controller.cc
@@ -269,9 +269,14 @@ void ImmersiveFullscreenController::SetEnabled(WindowType window_type,
 
   EnableWindowObservers(enabled_);
 
+  LOG(ERROR) << "SetEnabled:" << enabled;

[reveman, 2016/08/15 17:28:01]

debug code?

[oshima, 2016/08/15 17:34:34]

Uploading new CL was stuck in the comment input :(. Uploaded new patch.

+
   ash::wm::WindowState* window_state = wm::GetWindowState(native_window_);
   // Auto hide the shelf in immersive fullscreen instead of hiding it.
-  window_state->set_hide_shelf_when_fullscreen(!enabled);
+  // window_state->_shelf_when_fullscreen(!enabled);

[reveman, 2016/08/15 17:28:01]

debug code?

+
+  window_state->set_shelf_mode_in_fullscreen(
+      ash::wm::WindowState::SHELF_AUTO_HIDE_VISIBLE);
 
   // Update the window's immersive mode state for the window manager.
   window_state->set_in_immersive_fullscreen(enabled);