chromeos: Skip keyboard driven OOBE in multi-process mash

Workaround for an occasional crash we see in the autotest lab.
I'm just skipping the code so we can put MashLogin in the CQ.

Bug: 869385
Change-Id: I1267922036d3ab88276a2315dc9d3bb7d2ed2020
Reviewed-on: https://chromium-review.googlesource.com/1210683Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589234}

chrome/browser/chromeos/login/ui/login_display_host_webui.cc

@@ -939,9 +939,10 @@ void LoginDisplayHostWebUI::InitLoginWindowAndView() {
   if (login_window_)
     return;
 
-  if (system::InputDeviceSettings::Get()->ForceKeyboardDrivenUINavigation()) {
+  // TODO(crbug.com/881390): Mash support for keyboard driven OOBE.
+  if (!features::IsMultiProcessMash() &&
+      system::InputDeviceSettings::ForceKeyboardDrivenUINavigation()) {
     views::FocusManager::set_arrow_key_traversal_enabled(true);
-    // crbug.com/405859
     focus_ring_controller_ = std::make_unique<ash::FocusRingController>();
     focus_ring_controller_->SetVisible(true);