Revert 187767 "Add a unified observer to replace NetworkManagerO..."

Revert 187767 "Add a unified observer to replace NetworkManagerO..."

Reverting because it seems to cause crashes in VMTests on Chrome OS bots.

> Add a unified observer to replace NetworkManagerObserver
>
> The new observer implementation allows one to use either of NetworkLibrary
> or NetworkStateHandler to be notified of manager events.
>
> Also, switch over a few trivial NetworkManagerObserver consumers to
> use this new observer.
>
> TBR=sky@ for chrome/*.gypi changes
>
> BUG=chromium:181250, chromium:167232
> TEST=existing tests, tested on device
>
>
> Review URL: https://chromiumcodereview.appspot.com/12729002

TBR=gauravsh@chromium.org
Review URL: https://codereview.chromium.org/12693004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@187794 0039d316-1c4b-4281-b951-d872f2087c98