Revert of Use ExtensionRegistryObserver instead of deprecated extension notification from autocomplete (https://codereview.chromium.org/
271393003/)
Reason for revert:
Crash is reported.
See https://code.google.com/p/chromium/issues/detail?id=373624
Original issue's description:
> Use extensions::ExtensionRegistryObserver instead of deprecated extension notification from autocomplete
>
> R=pkasting@chromium.org
> CC=kalman@chromium.org
> BUG=354046, 354458
> TEST=unit_tests
>
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=270268
TBR=pkasting@chromium.org,kalman@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=354046, 354458
Review URL: https://codereview.chromium.org/
290043003
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@270764 0039d316-1c4b-4281-b951-d872f2087c98