ui: Remove unused Layer API.

ui: Remove unused Layer API.

This functionality is unused now that components/exo code is
using SetShowSurface.

This is effectively a reverts
8e3239023e76f7c30e8925bd541cc9b5965a54db and
fca687e21055ccab05cdd81b3fc8cf1b1f256d8c.

BUG=549781, 610086
TBR=piman@chromium.org

Committed: https://crrev.com/fb8a6e63a1a18ae7fced2c373fdc06ab5dc6786d
Cr-Commit-Position: refs/heads/master@{#414950}

[reveman, 2016-08-27 23:16:34]

The CQ bit was checked by reveman@chromium.org

[commit-bot: I haz the power, 2016-08-27 23:16:49]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-28 01:32:34]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-28 01:34:37]

Description was changed from

==========
ui: Remove unused Layer API.

This functionality is unused now that components/exo code is
using SetShowSurface.

This is effectively a reverts
8e3239023e76f7c30e8925bd541cc9b5965a54db and
fca687e21055ccab05cdd81b3fc8cf1b1f256d8c.

BUG=549781,610086
TBR=piman@chromium.org
==========

to

==========
ui: Remove unused Layer API.

This functionality is unused now that components/exo code is
using SetShowSurface.

This is effectively a reverts
8e3239023e76f7c30e8925bd541cc9b5965a54db and
fca687e21055ccab05cdd81b3fc8cf1b1f256d8c.

BUG=549781,610086
TBR=piman@chromium.org

Committed: https://crrev.com/fb8a6e63a1a18ae7fced2c373fdc06ab5dc6786d
Cr-Commit-Position: refs/heads/master@{#414950}
==========

[commit-bot: I haz the power, 2016-08-28 01:34:37]

Patchset 1 (id:??) landed as
https://crrev.com/fb8a6e63a1a18ae7fced2c373fdc06ab5dc6786d
Cr-Commit-Position: refs/heads/master@{#414950}