Fix WeakPtrFactory members in chromeos/

Fix WeakPtrFactory members in chromeos/

This forces WeakPtrs to be invalidated before other members' destructors run.
See the bug or the documentation of WeakPtrFactory for more information. I'm
in the process of trying to turn on a clang check for this (see the bug).

BUG=303818
R=derat@chromium.org
TBR=stevenjb@chromium.org

Committed: https://crrev.com/4b73fadb148e51fdc0abff8ccc42bf33a0dc4efd
Cr-Commit-Position: refs/heads/master@{#311383}

[Daniel Erat, 2015-01-13 23:30:48]

lgtm

[dmichael (off chromium), 2015-01-13 23:35:36]

The CQ bit was checked by dmichael@chromium.org

[commit-bot: I haz the power, 2015-01-13 23:36:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/816973003/1

[commit-bot: I haz the power, 2015-01-13 23:42:19]

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

[commit-bot: I haz the power, 2015-01-13 23:42:20]

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

[dmichael (off chromium), 2015-01-13 23:47:38]

I didn't see that chromeos/network has set noparent (I thought we didn't do that
anymore?)

TBRed stevenjb. Thanks!

[dmichael (off chromium), 2015-01-13 23:47:43]

The CQ bit was checked by dmichael@chromium.org

[commit-bot: I haz the power, 2015-01-13 23:48:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/816973003/1

[commit-bot: I haz the power, 2015-01-14 01:19:26]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-14 01:20:23]

Patchset 1 (id:??) landed as
https://crrev.com/4b73fadb148e51fdc0abff8ccc42bf33a0dc4efd
Cr-Commit-Position: refs/heads/master@{#311383}