Mixed Content: Remove redundant pref from tests.

Mixed Content: Remove redundant pref from tests.

Patch 1: Blink: https://codereview.chromium.org/957263002/
Patch 2: Chromium: https://codereview.chromium.org/960853002
Patch 3: [THIS PATCH]

BUG=462158

[Mike West, 2015-02-26 10:57:30]

mkwst@chromium.org changed reviewers:
+ jochen@chromium.org

[Mike West, 2015-02-26 10:57:37]

3/3.

[jochen (gone - plz use gerrit), 2015-02-26 15:09:24]

lgtm

[Mike West, 2015-02-27 10:08:24]

The CQ bit was checked by mkwst@chromium.org

[commit-bot: I haz the power, 2015-02-27 10:09:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/961633002/1

[Mike West, 2015-02-27 11:48:44]

The CQ bit was unchecked by mkwst@chromium.org

[Mike West, 2015-03-12 13:49:52]

The CQ bit was checked by mkwst@chromium.org

[commit-bot: I haz the power, 2015-03-12 13:50:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/961633002/1

[commit-bot: I haz the power, 2015-03-12 21:09:16]

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

[commit-bot: I haz the power, 2015-03-12 21:09:17]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/5...)