The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bb1b5cd67a3b5459cde2950c037776f88f9776e3

commit bb1b5cd67a3b5459cde2950c037776f88f9776e3
Author: sky <sky@chromium.org>
Date: Sun Sep 18 17:27:23 2016

Makes WindowTree::DeleteWindow() unembed for roots

Currently DeleteWindow() is (mostly) ignored if the client doesn't own
the root. This change allows the client to call delete on a root and
it's treated as unembedded the client from that root.

BUG= 647509 
TEST=covered by tests
R=sadrul@chromium.org

Review-Url: https://codereview.chromium.org/2349003002
Cr-Commit-Position: refs/heads/master@{#419401}

[modify] https://crrev.com/bb1b5cd67a3b5459cde2950c037776f88f9776e3/services/ui/public/interfaces/window_tree.mojom
[modify] https://crrev.com/bb1b5cd67a3b5459cde2950c037776f88f9776e3/services/ui/ws/server_window.cc
[modify] https://crrev.com/bb1b5cd67a3b5459cde2950c037776f88f9776e3/services/ui/ws/server_window.h
[modify] https://crrev.com/bb1b5cd67a3b5459cde2950c037776f88f9776e3/services/ui/ws/server_window_observer.h
[modify] https://crrev.com/bb1b5cd67a3b5459cde2950c037776f88f9776e3/services/ui/ws/window_server.cc
[modify] https://crrev.com/bb1b5cd67a3b5459cde2950c037776f88f9776e3/services/ui/ws/window_server.h
[modify] https://crrev.com/bb1b5cd67a3b5459cde2950c037776f88f9776e3/services/ui/ws/window_tree.cc
[modify] https://crrev.com/bb1b5cd67a3b5459cde2950c037776f88f9776e3/services/ui/ws/window_tree.h
[modify] https://crrev.com/bb1b5cd67a3b5459cde2950c037776f88f9776e3/services/ui/ws/window_tree_client_unittest.cc