Revert of Introduce the devices Mojo app

Revert of Introduce the devices Mojo app (patchset #5 id:160001 of https://codereview.chromium.org/1165223004/)

Reason for revert:
This broke the Win 8 GN (dbg) and Win x64 GN (dbg) bots:

https://build.chromium.org/p/chromium.win/builders/Win8%20GN%20%28dbg%29/builds/7453
https://build.chromium.org/p/chromium.win/builders/Win%20x64%20GN%20%28dbg%29/builds/3219

Original issue's description:
> Introduce the devices Mojo app
>
> It's a small Mojo app that currently only hosts USB device
> services. This CL adds the app along with an apptest suite
> (run manually with mojo_runner mojo:devices_apptests).
>
> The app is hooked up to Chrome to run in the browser process,
> though there are currently no production code paths which
> cause the app to launch.
>
> BUG=498557
>
> Committed: https://crrev.com/ed800dc138edfa261aa766281b96f736ff9824f6
> Cr-Commit-Position: refs/heads/master@{#333899}

TBR=reillyg@chromium.org,sky@chromium.org,rockot@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=498557
Committed: https://crrev.com/0e5fc2b42b268fab5d9ea3276235db58b7d61d1c
Cr-Commit-Position: refs/heads/master@{#333942}

[kjellander_chromium, 2015-06-11 13:40:42]

Created Revert of Introduce the devices Mojo app

[commit-bot: I haz the power, 2015-06-11 13:40:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1176383002/1

[commit-bot: I haz the power, 2015-06-11 13:41:37]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-11 13:42:19]

Patchset 1 (id:??) landed as
https://crrev.com/0e5fc2b42b268fab5d9ea3276235db58b7d61d1c
Cr-Commit-Position: refs/heads/master@{#333942}