Deprecate prefs::kSupervisedUserCreationAllowed

It was used to back a policy which was removed in
https://crrev.com/c/1224033, and supervised user creation itself has
been gone for way longer.

Bug: 828890
Change-Id: I3a764e88f72599799263d1dc141d88e5e8b85a91
Reviewed-on: https://chromium-review.googlesource.com/1245708Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594715}

chrome/browser/prefs/browser_prefs.cc

@@ -369,6 +369,8 @@ const char kTrustedDownloadSources[] = "trusted_download_sources";
 #if defined(OS_WIN)
 const char kLastWelcomedOSVersion[] = "browser.last_welcomed_os_version";
 #endif
+const char kSupervisedUserCreationAllowed[] =
+    "profile.managed_user_creation_allowed";
 
 // Register prefs used only for migration (clearing or moving to a new key).
 void RegisterProfilePrefsForMigration(
@@ -392,6 +394,7 @@ void RegisterProfilePrefsForMigration(
   registry->RegisterIntegerPref(kModuleConflictBubbleShown, 0);
   registry->RegisterIntegerPref(kOptionsWindowLastTabIndex, 0);
   registry->RegisterStringPref(kTrustedDownloadSources, std::string());
+  registry->RegisterBooleanPref(kSupervisedUserCreationAllowed, true);
 }
 
 }  // namespace
@@ -846,4 +849,5 @@ void MigrateObsoleteProfilePrefs(Profile* profile) {
   profile_prefs->ClearPref(kModuleConflictBubbleShown);
   profile_prefs->ClearPref(kOptionsWindowLastTabIndex);
   profile_prefs->ClearPref(kTrustedDownloadSources);
+  profile_prefs->ClearPref(kSupervisedUserCreationAllowed);
 }

chrome/browser/supervised_user/supervised_user_service.cc

@@ -151,7 +151,6 @@ void SupervisedUserService::RegisterProfilePrefs(
   registry->RegisterDictionaryPref(prefs::kSupervisedUserManualURLs);
   registry->RegisterIntegerPref(prefs::kDefaultSupervisedUserFilteringBehavior,
                                 SupervisedUserURLFilter::ALLOW);
-  registry->RegisterBooleanPref(prefs::kSupervisedUserCreationAllowed, true);
   registry->RegisterBooleanPref(prefs::kSupervisedUserSafeSites, true);
   for (const char* pref : kCustodianInfoPrefs) {
     registry->RegisterStringPref(pref, std::string());

chrome/common/pref_names.cc

@@ -1185,10 +1185,6 @@ const char kPrintingSizeDefault[] = "printing.size_default";
 const char kDefaultSupervisedUserFilteringBehavior[] =
     "profile.managed.default_filtering_behavior";
 
-// Whether this user is permitted to create supervised users.
-const char kSupervisedUserCreationAllowed[] =
-    "profile.managed_user_creation_allowed";
-
 // List pref containing the users supervised by this user.
 const char kSupervisedUsers[] = "profile.managed_users";
 

chrome/common/pref_names.h

@@ -399,7 +399,6 @@ extern const char kPrintingSizeDefault[];
 
 extern const char kDefaultSupervisedUserFilteringBehavior[];
 
-extern const char kSupervisedUserCreationAllowed[];
 extern const char kSupervisedUsers[];
 
 extern const char kMessageCenterDisabledExtensionIds[];