Fix crash when switching to a profile that cannot be opened

chrome/browser/profiles/profile_manager.h

Index: chrome/browser/profiles/profile_manager.h
diff --git a/chrome/browser/profiles/profile_manager.h b/chrome/browser/profiles/profile_manager.h
index e3e742c9995536c5defdc4a8f7001d3872563c56..3133365136179ad19bf9982149b7a51c72422995 100644
--- a/chrome/browser/profiles/profile_manager.h
+++ b/chrome/browser/profiles/profile_manager.h
@@ -401,6 +401,10 @@ class ProfileManager : public base::NonThreadSafe,
   typedef std::map<base::FilePath, linked_ptr<ProfileInfo> > ProfilesInfoMap;
   ProfilesInfoMap profiles_info_;
 
+  // Owns profiles that fail initialization. Like normal profiles, they must not
+  // be deleted before shutdown.

[Peter Kasting, 2016/06/16 07:02:11]

I'm uncomfortable with having this code and comment when you say you don't
understand the pref store well enough to fix this (or, apparently, even comment
in detail about what's going on here).

If you don't understand well enough to do that, how do I know the code you're
writing here is correct, and not just a band-aid?  In general my reply to such
things is "go back and keep investigating until you do understand it better, or
find someone who does and work with them to determine the correct long term
fix".

[WC Leung, 2016/06/16 10:04:10]

Actually there was some discussion about deleting profiles in the design
document "Profile Architecture". It reads like this:
So this is the "reason" that normal profiles are deleted when chrome is shutting
down, instead of when the last browser windows of the profile is closed. The
ugly thing that this CL does is to extend this workaround to profiles that fails
to initialize. Since this workaround is already being used and documented I have
grounds to believe (sadly not know) that it will not make things worse instead
of better.

For the crash part, I have found two services (one is JSONPrefStore) is crashing
when the profile is deleted. Since I was unable to fix JSONPrefStore, I don't
know whether there are other services crashing on such a deletion. I would like
to say "probably" for the existing of the third crashing service.

Anyway, it is worth asking owners of pref store to have a discussion.

Bauer: WDYT?

[Peter Kasting, 2016/06/16 10:59:59]

FWIW, it seems very wrong to me for anyone to be depending-until-chrome-shutdown
on any part of a profile that couldn't even be initialized.

[Bernhard Bauer, 2016/06/16 13:40:25]

We use JSONPrefStore in a couple of different places. Do you know which one
crashes? Do you have a stack trace or something?

+  std::vector<std::unique_ptr<Profile>> failed_profiles_;
+
   // Manages the process of creating, deleteing and updating Desktop shortcuts.
   std::unique_ptr<ProfileShortcutManager> profile_shortcut_manager_;