Implement new network change notifier that uses NetworkStateHandler

Implement new network change notifier that uses NetworkStateHandler

[Reland of https://codereview.chromium.org/11469044/ with rebase over
 changes to the new network state handler.]

This implements the new network change notifier that informs the Chrome
network stack of connectivity changes.

It's currently behind the --enable-new-network-handlers command line flag.

BUG=chromium-os:159647
TEST=unit tests, gmerged on a device and ensured offline->online and
online->offline transitions are correctly detected.


Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=174530

[stevenjb, 2012-12-21 21:20:11]

lgtm

[commit-bot: I haz the power, 2012-12-21 21:39:17]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gauravsh@chromium.org/11662014/1

[commit-bot: I haz the power, 2012-12-22 01:08:34]

Retried try job too often on win_rel for step(s) browser_tests

[commit-bot: I haz the power, 2012-12-22 02:35:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gauravsh@chromium.org/11662014/1

[commit-bot: I haz the power, 2012-12-22 06:41:31]

Retried try job too often on win_rel for step(s) browser_tests

[commit-bot: I haz the power, 2012-12-22 08:25:22]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gauravsh@chromium.org/11662014/1

[commit-bot: I haz the power, 2012-12-22 17:22:27]

Change committed as 174530