Some fixes for gn examples

Some fixes for gn examples

Fixes up various dependency bugs that prevent mojo_demo_launcher +
mojo_html_viewer from working.

Once we are gn check clean this should be easy to enforce with a script,
but for now it's manual testing.

R=abarth@chromium.org

Committed: https://crrev.com/f8831db369da6c5c334a0defae6f22358760cce2
Cr-Commit-Position: refs/heads/master@{#297023}

[abarth-chromium, 2014-09-26 19:59:38]

lgtm

[jamesr, 2014-09-26 20:01:48]

The CQ bit was checked by jamesr@chromium.org

[commit-bot: I haz the power, 2014-09-26 20:02:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/608023002/1

[commit-bot: I haz the power, 2014-09-26 20:34:34]

Committed patchset #1 (id:1) as 472ca80c5830a67922b2dba9e82f96615c0c8e3c

[commit-bot: I haz the power, 2014-09-26 20:35:29]

Patchset 1 (id:??) landed as
https://crrev.com/f8831db369da6c5c334a0defae6f22358760cce2
Cr-Commit-Position: refs/heads/master@{#297023}