The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9e38764793efdaef079e7ece7028ee84a9482a63

commit 9e38764793efdaef079e7ece7028ee84a9482a63
Author: erg <erg@chromium.org>
Date: Fri Mar 10 22:38:39 2017

aura-mus: wire up drag and drop.

- Drag now works again.
- Ensure the nested run loop gets torn down on errors.
- Adds logs of dvlogs for debugging when needed.
- Moves registration of aura components to //ui/aura/.

BUG= 699235 , 665077 

Review-Url: https://codereview.chromium.org/2739213003
Cr-Commit-Position: refs/heads/master@{#456193}

[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/services/ui/ws/drag_controller.cc
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/services/ui/ws/drag_controller.h
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/services/ui/ws/window_tree.cc
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/ui/aura/env.cc
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/ui/aura/env.h
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/ui/aura/mus/drag_drop_controller_mus.cc
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/ui/aura/mus/window_port_mus.cc
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/ui/aura/mus/window_port_mus.h
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/ui/aura/mus/window_tree_client.cc
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/ui/aura/mus/window_tree_client.h
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/ui/views/mus/desktop_window_tree_host_mus.cc
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/ui/views/mus/mus_client.cc
[modify] https://crrev.com/9e38764793efdaef079e7ece7028ee84a9482a63/ui/views/mus/mus_client.h