Cast: Fix memory leak in cast_unittests

Cast: Fix memory leak in cast_unittests

Testing clock needs an owner. Put a scoped_ptr<> to where it was first
created.

BUG=400728
Committed: https://crrev.com/6618cd1694953a98e999f7b4d0b4db95717a17aa
Cr-Commit-Position: refs/heads/master@{#292441}

[hubbe, 2014-08-22 16:35:49]

lgtm

[Alpha Left Google, 2014-08-22 17:32:11]

The CQ bit was checked by hclam@chromium.org

[commit-bot: I haz the power, 2014-08-22 17:33:26]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/hclam@chromium.org/488133005/20001

[commit-bot: I haz the power, 2014-08-22 18:27:07]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_chromium_gn_compile_rel on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)
  android_dbg_tests_recipe on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_dbg_tes...)

[commit-bot: I haz the power, 2014-08-22 18:30:13]

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

[commit-bot: I haz the power, 2014-08-22 18:30:13]

Try jobs failed on following builders:
  android_chromium_gn_compile_rel on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)

[Alpha Left Google, 2014-08-28 18:48:27]

The CQ bit was checked by hclam@chromium.org

[commit-bot: I haz the power, 2014-08-28 18:50:27]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/hclam@chromium.org/488133005/20001

[commit-bot: I haz the power, 2014-08-28 19:20:20]

Committed patchset #2 (id:20001) as 27c31290f4c6cf3d6eabffafc6f1df21b2ba34c3

[commit-bot: I haz the power, 2014-09-10 03:01:30]

Patchset 2 (id:??) landed as
https://crrev.com/6618cd1694953a98e999f7b4d0b4db95717a17aa
Cr-Commit-Position: refs/heads/master@{#292441}