The User Manager should be backed by a special profile, not the guest one.

The User Manager should be backed by a special profile, not the guest one.

We've been using the generic guest profile to also back the User Manager
widget. The guest profile recently became an off-the-record profile which
means that when the last guest browser window is closed, the ProfileDestroyer
is going to start cleaning all the OTR stuff. This will then crash if the
User Manager is open because we now have a dangling renderer.

The solution is to create a special profile only to be used by the User
Manager. This profile doesn't get deleted, is not added to the ProfileInfoCache,
and can't be accessed through the UI.

BUG=363565

[noms (inactive), 2014-04-16 17:46:08]

+ Nico for rubber stamp on chrome/browser/ui and chrome/common. 

The UI changes are just a function name change. The c/common change adds a new
constant for the path of the special profile backing the user manager.

[Nico, 2014-04-16 18:03:15]

lgtm

https://codereview.chromium.org/239543012/diff/1/chrome/common/chrome_constan...
File chrome/common/chrome_constants.h (right):

https://codereview.chromium.org/239543012/diff/1/chrome/common/chrome_constan...
chrome/common/chrome_constants.h:52: extern const base::FilePath::CharType
kUserManagerProfileDir[];
Any reason these aren't char like kInitialProfile? (With AppendASCII() on
FilePath, it shouldn't make much of a difference at the using site?)

[noms (inactive), 2014-04-16 18:36:02]

I've also updated the tests, and added a new function to the
TestingProfileManager to deal with this new magical profile. Please take a look
:)

https://codereview.chromium.org/239543012/diff/1/chrome/common/chrome_constan...
File chrome/common/chrome_constants.h (right):

https://codereview.chromium.org/239543012/diff/1/chrome/common/chrome_constan...
chrome/common/chrome_constants.h:52: extern const base::FilePath::CharType
kUserManagerProfileDir[];
Done.
On 2014/04/16 18:03:16, Nico wrote:
> Any reason these aren't char like kInitialProfile? (With AppendASCII() on
> FilePath, it shouldn't make much of a difference at the using site?)

[noms (inactive), 2014-04-17 17:18:02]

Rachel: ping! :)

[rpetterson, 2014-04-17 17:49:21]

lgtm

[noms (inactive), 2014-04-17 17:51:45]

The CQ bit was checked by noms@chromium.org

[commit-bot: I haz the power, 2014-04-17 17:52:37]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/noms@chromium.org/239543012/2

[commit-bot: I haz the power, 2014-04-17 19:00:37]

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

[commit-bot: I haz the power, 2014-04-17 19:00:37]

Try jobs failed on following builders:
  tryserver.chromium on linux_chromium_rel

[noms (inactive), 2014-04-22 17:08:17]

I'm closing this CL without landing it, because it turns out more things that
aren't the user manager are made grumpy by the Guest profile deleting itself
when the last browser closes, so the fix needs to be done in the Guest profile
instead.

Thanks for the review though! :(