Mark supervised profiles as such immediately when they're created.

chrome/browser/profiles/profile_manager.cc

Index: chrome/browser/profiles/profile_manager.cc
diff --git a/chrome/browser/profiles/profile_manager.cc b/chrome/browser/profiles/profile_manager.cc
index 6140d201f264a2dcd22f13cda83b38abbe0ead3d..bc1a9066a9c81ad29ca3fe85532ad0d9e6d6d264 100644
--- a/chrome/browser/profiles/profile_manager.cc
+++ b/chrome/browser/profiles/profile_manager.cc
@@ -551,6 +551,7 @@ bool ProfileManager::AddProfile(Profile* profile) {
   }
 
   RegisterProfile(profile, true);
+  InitProfileUserPrefs(profile);

[rpetterson, 2013/10/01 20:19:57]

It doesn't really change the call flow, so I'm curious why you moved this up
here?

[Bernhard Bauer, 2013/10/01 20:42:15]

InitProfileUserPrefs() is where we mark a profile as managed when it is
initially created. I need to run this before the BrowserContextKeyedServices are
created, because some of them might do their initialization differently for a
managed profile. I updated the CL description to (hopefully) make that a bit
clearer.

[rpetterson, 2013/10/07 23:22:49]

I understand better what's going on now. However, I don't think managed mode is
the only type of profile creation which uses a delegate so how will this affect
other profile creation flows? If it won't, perhaps it would be simpler to bump
up InitProfileUserPrefs to just before the browser services creation for
everyone.

[Bernhard Bauer, 2013/10/08 14:56:01]

This CL actually does change the behavior for everyone, it's just that
supervised user creation is the rationale behind it, so that's what I mentioned
in the description.

Or are you refering to moving it to another place closer to browser services
creation?

[rpetterson, 2013/10/08 18:02:55]

Yes. If we're changing it for everyone, there should be just one path. With this
CL, you can init the prefs either in OnPrefsLoaded via the delegate or in
AddProfile. We should eliminate the use of the delegate in this case and just
call InitProfileUserPrefs right before browser services creation (like
ProfileImpl::785). Perhaps make that function static or move it to the profile?

   DoFinalInit(profile, ShouldGoOffTheRecord(profile));
   return true;
 }
@@ -714,7 +715,6 @@ void ProfileManager::BrowserListObserver::OnBrowserSetLastActive(
 #endif  // !defined(OS_ANDROID) && !defined(OS_IOS)
 
 void ProfileManager::DoFinalInit(Profile* profile, bool go_off_the_record) {
-  InitProfileUserPrefs(profile);
   DoFinalInitForServices(profile, go_off_the_record);
   AddProfileToCache(profile);
   DoFinalInitLogging(profile);
@@ -805,6 +805,10 @@ Profile* ProfileManager::CreateProfileAsyncHelper(const base::FilePath& path,
                                 Profile::CREATE_MODE_ASYNCHRONOUS);
 }
 
+void ProfileManager::OnPrefsLoaded(Profile* profile) {
+  InitProfileUserPrefs(profile);
+}
+
 void ProfileManager::OnProfileCreated(Profile* profile,
                                       bool success,
                                       bool is_new_profile) {
@@ -996,8 +1000,14 @@ void ProfileManager::InitProfileUserPrefs(Profile* profile) {
   if (!profile->GetPrefs()->HasPrefPath(prefs::kProfileName))
     profile->GetPrefs()->SetString(prefs::kProfileName, profile_name);
 
-  if (!profile->GetPrefs()->HasPrefPath(prefs::kManagedUserId))
+  if (!profile->GetPrefs()->HasPrefPath(prefs::kManagedUserId)) {
+    if (managed_user_id.empty() &&
+        CommandLine::ForCurrentProcess()->HasSwitch(
+            switches::kNewProfileIsSupervised)) {
+      managed_user_id = "Test ID";
+    }
     profile->GetPrefs()->SetString(prefs::kManagedUserId, managed_user_id);
+  }
 }
 
 void ProfileManager::SetGuestProfilePrefs(Profile* profile) {