Move wm/core to wm namespace.

Move wm/core to wm namespace.

Also sets up new targets for wm_core, wm_core_unittests, etc.

R=sky@chromium.org
TBR=sky@chromium.org
BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=256680

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=256839

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=257183

[sky, 2014-03-12 20:45:16]

Rubber stamp LGTM

[Ben Goodger (Google), 2014-03-12 22:36:26]

Committed patchset #2 manually as r256680 (presubmit successful).

[Ben Goodger (Google), 2014-03-13 05:08:04]

The CQ bit was checked by ben@chromium.org

[commit-bot: I haz the power, 2014-03-13 05:13:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ben@chromium.org/196063002/110001

[commit-bot: I haz the power, 2014-03-13 05:29:19]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-03-13 05:29:20]

Try jobs failed on following builders:
  tryserver.chromium on linux_chromium_rel
  tryserver.chromium on mac_chromium_compile_dbg

[Ben Goodger (Google), 2014-03-13 15:32:15]

Committed patchset #5 manually as r256839 (presubmit successful).

[Ben Goodger (Google), 2014-03-14 14:18:36]

The CQ bit was checked by ben@chromium.org

[commit-bot: I haz the power, 2014-03-14 14:18:44]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ben@chromium.org/196063002/270001

[commit-bot: I haz the power, 2014-03-14 14:21:33]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-03-14 14:21:33]

Try jobs failed on following builders:
  tryserver.chromium on linux_chromium_clang_dbg

[Ben Goodger (Google), 2014-03-14 19:57:05]

Committed patchset #15 manually as r257183 (presubmit successful).