Fixed exo widget initialization for popup windows.

The bug was introduced when we forced override redirect windows to use
container_ by checking if container_ was a desktop shell. Unfortunately
this does not work for popups which explicitly set a non-desktop
container (kShellWindowId_MenuContainer).

This fix removes the logic to explicitly set the container for popups,
which allows them to use parent_ as the container.

(cherry picked from commit bb64e21dd27185cda3edafb4a668b6d8086c0972)

Bug: 971305, b:133854684
Change-Id: Ie12d38afdb148e8e47d36dee57e3eb55049db19d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1647644
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Commit-Queue: Nic Hollingum <hollingum@google.com>
Cr-Original-Commit-Position: refs/heads/master@{#667813}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1653752
Reviewed-by: Nic Hollingum <hollingum@google.com>
Cr-Commit-Position: refs/branch-heads/3809@{#239}
Cr-Branched-From: d82dec1a818f378c464ba307ddd9c92133eac355-refs/heads/master@{#665002}

• components/exo/wayland/zxdg_shell.cc[diff]