[Profiles] Create a profile moar better after deleting the only existing profile.

[Profiles] Create a profile moar better after deleting the only existing profile.

The problem was that we only created the new profile if we deleted the
active profile, and it was the only existing profile. Since guest mode came
along, we could also delete the only profile when the active profile was
the guest one (which doesn't really count as a profile), so you'd be left in
this borked state of "no profiles in Chrome, oops".

For brownie points, I also added tests for both of these "only existing profile
deleted" scenarios. :)

BUG=393901
TEST=See bug description.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=284096

[noms (inactive), 2014-07-15 21:17:15]

Hiya Elliot,

Rachel is on vacation, so you're my de-facto Profiles owner of choice :)
I fixed a profile deletion related bug. Please take a look. Thanks!

[erg, 2014-07-15 21:39:12]

lgtm

[noms (inactive), 2014-07-15 23:42:12]

+ sky for chrome/test/base stamp

[sky, 2014-07-16 14:38:24]

LGTM

[noms (inactive), 2014-07-16 14:50:16]

The CQ bit was checked by noms@chromium.org

[commit-bot: I haz the power, 2014-07-16 14:53:58]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/noms@chromium.org/396773002/1

[noms (inactive), 2014-07-16 19:23:16]

The CQ bit was unchecked by noms@chromium.org

[noms (inactive), 2014-07-17 17:17:05]

The CQ bit was checked by noms@chromium.org

[commit-bot: I haz the power, 2014-07-17 17:18:31]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/noms@chromium.org/396773002/100001

[commit-bot: I haz the power, 2014-07-17 19:51:17]

FYI, CQ is re-trying this CL (attempt #1).
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, 2014-07-17 20:15:02]

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

[commit-bot: I haz the power, 2014-07-17 20:15:03]

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

[noms (inactive), 2014-07-18 14:15:00]

The CQ bit was checked by noms@chromium.org

[commit-bot: I haz the power, 2014-07-18 14:15:53]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/noms@chromium.org/396773002/100001

[commit-bot: I haz the power, 2014-07-18 14:39:01]

FYI, CQ is re-trying this CL (attempt #1).
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, 2014-07-18 15:39:38]

Change committed as 284096