Fail gracefully if the active profile can't be found in the ProfileInfoCache

Fail gracefully if the active profile can't be found in the ProfileInfoCache

The underlying reason for not finding the profile is probably crbug.com/464616,
but this should still not crash.

BUG=421215
Committed: https://crrev.com/3c62345e860267d5f190f66dcb3994d97f111a28
Cr-Commit-Position: refs/heads/master@{#321353}

[noms (inactive), 2015-03-18 21:34:00]

noms@chromium.org changed reviewers:
+ sky@chromium.org

[noms (inactive), 2015-03-18 21:34:01]

If for whatever reason the profile isn't in the ProfileInfoCache (like that
trailing slashes bug), Chrome shouldn't crash.

Please take a look. Thanks!

[sky, 2015-03-18 23:03:45]

LGTM

[noms, 2015-03-19 00:10:19]

The CQ bit was checked by noms@google.com

[commit-bot: I haz the power, 2015-03-19 00:11:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1021613002/1

[commit-bot: I haz the power, 2015-03-19 04:12:56]

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

[commit-bot: I haz the power, 2015-03-19 04:12:57]

Try jobs failed on following builders:
  linux_chromium_chromeos_compile_dbg_ng on tryserver.chromium.linux
(JOB_TIMED_OUT, no build URL)
Timed out jobs are not retried to avoid causing additional load on the builders
with large pending queues.

[noms (inactive), 2015-03-19 14:04:51]

The CQ bit was checked by noms@chromium.org

[commit-bot: I haz the power, 2015-03-19 14:05:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1021613002/1

[commit-bot: I haz the power, 2015-03-19 14:27:43]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-19 14:28:19]

Patchset 1 (id:??) landed as
https://crrev.com/3c62345e860267d5f190f66dcb3994d97f111a28
Cr-Commit-Position: refs/heads/master@{#321353}