Adds some debugging code to verify the dictionaries are non-null at

Adds some debugging code to verify the dictionaries are non-null at
construction time. Based on some crashes it seems as though these can
be NULL later on.

BUG=121584
TEST=none
R=brettw@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=130833

[brettw, 2012-04-03 22:03:25]

lgtm

[commit-bot: I haz the power, 2012-04-03 22:07:43]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/sky@chromium.org/9958134/1

[commit-bot: I haz the power, 2012-04-04 02:28:04]

Try job failure for 9958134-1 (retry) on win_rel for steps "browser_tests,
unit_tests".
It's a second try, previously, steps "browser_tests, unit_tests,
installer_util_unittests" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2012-04-04 03:39:35]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/sky@chromium.org/9958134/1

[commit-bot: I haz the power, 2012-04-04 06:33:18]

Try job failure for 9958134-1 (retry) on win_rel for steps "browser_tests,
unit_tests".
It's a second try, previously, steps "browser_tests, unit_tests" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...