Add sanity check to troubleshoot crbug.com/374273

Add sanity check to troubleshoot crbug.com/374273

BUG=374273
R=msw@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=271238

[msw, 2014-05-17 00:31:15]

lgtm. it'd be nice if we cached the images, so we didn't have to retrieve them
by ID on every paint call.

[oshima, 2014-05-17 00:57:24]

The CQ bit was checked by oshima@chromium.org

[commit-bot: I haz the power, 2014-05-17 00:57:43]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/oshima@chromium.org/287243002/1

[commit-bot: I haz the power, 2014-05-17 06:59:56]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  android_dbg_triggered_tests on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg_triggered...)

[commit-bot: I haz the power, 2014-05-17 08:14:45]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-05-17 08:14:46]

Try jobs failed on following builders:
  android_dbg_triggered_tests on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg_triggered...)

[oshima, 2014-05-17 09:29:09]

The CQ bit was checked by oshima@chromium.org

[commit-bot: I haz the power, 2014-05-17 09:29:28]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/oshima@chromium.org/287243002/1

[commit-bot: I haz the power, 2014-05-17 17:12:48]

Change committed as 271238