Reland: Remove some dead app host code.

Reland: Remove some dead app host code.

app_host.exe was removed in r220555. This change removes some dead code
that was left behind. Specifically:
- chrome_launcher_support no longer exposes any methods related to the
  AppHost.
- Chrome's uninstall prompt no longer has a special case to handle
  suppressing the "delete your profile" checkbox.
- Chrome and its installer no longer have a dependency on
  launcher_support.
- The installer no longer supports installing items from the webstore.
- GetUntrustedDataValue no longer has consumers and is gone.

BUG=297647
R=benwells@chromium.org,huangs@chromium.org,gab@chromium.org
TBR=grt@chromium.org
NOTRY=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285715

[grt (UTC plus 2), 2014-07-25 22:33:32]

relanding this after r285710 to un-break google chrome builds.

[grt (UTC plus 2), 2014-07-25 22:33:36]

The CQ bit was checked by grt@chromium.org

[commit-bot: I haz the power, 2014-07-25 22:35:16]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/grt@chromium.org/419913005/1

[commit-bot: I haz the power, 2014-07-25 22:54:54]

Change committed as 285715

[gab, 2014-07-28 13:51:39]

lgtm, in the future I'd advise to re-open the old CL and reland; makes it easier
to see the fix patch set's diff (or no diff in this case); also keeps history in
one place.

(you can re-open a closed CL from "Edit Issue").

Cheers,
Gab