We should use UserID object to identify users instead of username.

chrome/browser/supervised_user/legacy/supervised_user_sync_service.cc

Index: chrome/browser/supervised_user/legacy/supervised_user_sync_service.cc
diff --git a/chrome/browser/supervised_user/legacy/supervised_user_sync_service.cc b/chrome/browser/supervised_user/legacy/supervised_user_sync_service.cc
index 1da90a26e4197165ae2f9ec69f96ddc970dabdd0..88558e7b047deb1a86baa42077e35a138d4f3940 100644
--- a/chrome/browser/supervised_user/legacy/supervised_user_sync_service.cc
+++ b/chrome/browser/supervised_user/legacy/supervised_user_sync_service.cc
@@ -18,6 +18,7 @@
 #include "chrome/common/pref_names.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/signin/core/browser/signin_manager.h"
+#include "components/user_manager/user_id.h"
 #include "sync/api/sync_change.h"
 #include "sync/api/sync_data.h"
 #include "sync/api/sync_error.h"
@@ -51,7 +52,7 @@ const char kChromeOSAvatarPrefix[] = "chromeos-avatar-index:";
 const char kChromeAvatarPrefix[] = "chrome-avatar-index:";
 #endif
 
-SyncData CreateLocalSyncData(const std::string& id,
+SyncData CreateLocalSyncData(const user_manager::UserID& id,
                              const std::string& name,
                              bool acknowledged,
                              const std::string& master_key,
@@ -60,7 +61,7 @@ SyncData CreateLocalSyncData(const std::string& id,
                              const std::string& password_signature_key,
                              const std::string& password_encryption_key) {
   ::sync_pb::EntitySpecifics specifics;
-  specifics.mutable_managed_user()->set_id(id);
+  specifics.mutable_managed_user()->set_id(id.GetUserEmail());
   specifics.mutable_managed_user()->set_name(name);
   if (!chrome_avatar.empty())
     specifics.mutable_managed_user()->set_chrome_avatar(chrome_avatar);
@@ -78,10 +79,10 @@ SyncData CreateLocalSyncData(const std::string& id,
     specifics.mutable_managed_user()->
         set_password_encryption_key(password_encryption_key);
   }
-  return SyncData::CreateLocalData(id, name, specifics);
+  return SyncData::CreateLocalData(id.GetUserEmail(), name, specifics);
 }
 
-SyncData CreateSyncDataFromDictionaryEntry(const std::string& id,
+SyncData CreateSyncDataFromDictionaryEntry(const user_manager::UserID& id,
                                            const base::Value& value) {
   const base::DictionaryValue* dict = NULL;
   bool success = value.GetAsDictionary(&dict);
@@ -229,7 +230,7 @@ scoped_ptr<base::DictionaryValue> SupervisedUserSyncService::CreateDictionary(
 }
 
 void SupervisedUserSyncService::AddSupervisedUser(
-    const std::string& id,
+    const user_manager::UserID& id,
     const std::string& name,
     const std::string& master_key,
     const std::string& signature_key,
@@ -245,7 +246,7 @@ void SupervisedUserSyncService::AddSupervisedUser(
 }
 
 void SupervisedUserSyncService::UpdateSupervisedUser(
-    const std::string& id,
+    const user_manager::UserID& id,
     const std::string& name,
     const std::string& master_key,
     const std::string& signature_key,
@@ -261,7 +262,7 @@ void SupervisedUserSyncService::UpdateSupervisedUser(
 }
 
 void SupervisedUserSyncService::UpdateSupervisedUserImpl(
-    const std::string& id,
+    const user_manager::UserID& id,
     const std::string& name,
     const std::string& master_key,
     const std::string& signature_key,
@@ -273,9 +274,9 @@ void SupervisedUserSyncService::UpdateSupervisedUserImpl(
   scoped_ptr<base::DictionaryValue> value = CreateDictionary(
       name, master_key, signature_key, encryption_key, avatar_index);
 
-  DCHECK_EQ(add_user, !dict->HasKey(id));
+  DCHECK_EQ(add_user, !dict->HasKey(id.GetUserEmail()));
   base::DictionaryValue* entry = value.get();
-  dict->SetWithoutPathExpansion(id, value.release());
+  dict->SetWithoutPathExpansion(id.GetUserEmail(), value.release());
 
   if (!sync_processor_)
     return;
@@ -291,9 +292,9 @@ void SupervisedUserSyncService::UpdateSupervisedUserImpl(
   DCHECK(!error.IsSet()) << error.ToString();
 }
 
-void SupervisedUserSyncService::DeleteSupervisedUser(const std::string& id) {
+void SupervisedUserSyncService::DeleteSupervisedUser(const user_manager::UserID& id) {
   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
-  bool success = update->RemoveWithoutPathExpansion(id, NULL);
+  bool success = update->RemoveWithoutPathExpansion(id.GetUserEmail(), NULL);
   DCHECK(success);
 
   if (!sync_processor_)
@@ -303,7 +304,7 @@ void SupervisedUserSyncService::DeleteSupervisedUser(const std::string& id) {
   change_list.push_back(SyncChange(
       FROM_HERE,
       SyncChange::ACTION_DELETE,
-      SyncData::CreateLocalDelete(id, SUPERVISED_USERS)));
+      SyncData::CreateLocalDelete(id.GetUserEmail(), SUPERVISED_USERS)));
   SyncError sync_error =
       sync_processor_->ProcessSyncChanges(FROM_HERE, change_list);
   DCHECK(!sync_error.IsSet());
@@ -315,13 +316,13 @@ const base::DictionaryValue* SupervisedUserSyncService::GetSupervisedUsers() {
 }
 
 bool SupervisedUserSyncService::UpdateSupervisedUserAvatarIfNeeded(
-    const std::string& id,
+    const user_manager::UserID& id,
     int avatar_index) {
   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
   base::DictionaryValue* dict = update.Get();
-  DCHECK(dict->HasKey(id));
+  DCHECK(dict->HasKey(id.GetUserEmail()));
   base::DictionaryValue* value = NULL;
-  bool success = dict->GetDictionaryWithoutPathExpansion(id, &value);
+  bool success = dict->GetDictionaryWithoutPathExpansion(id.GetUserEmail(), &value);
   DCHECK(success);
 
   bool acknowledged = false;
@@ -378,7 +379,7 @@ bool SupervisedUserSyncService::UpdateSupervisedUserAvatarIfNeeded(
 }
 
 void SupervisedUserSyncService::ClearSupervisedUserAvatar(
-    const std::string& id) {
+    const user_manager::UserID& id) {
   bool cleared = UpdateSupervisedUserAvatarIfNeeded(id, kNoAvatar);
   DCHECK(cleared);
 }
@@ -447,7 +448,7 @@ SyncMergeResult SupervisedUserSyncService::MergeDataAndStartSyncing(
     change_list.push_back(
         SyncChange(FROM_HERE,
                    SyncChange::ACTION_ADD,
-                   CreateSyncDataFromDictionaryEntry(it.key(), it.value())));
+                   CreateSyncDataFromDictionaryEntry(user_manager::UserID::FromUserEmail(it.key()), it.value())));
   }
   result.set_error(sync_processor_->ProcessSyncChanges(FROM_HERE, change_list));
 
@@ -475,7 +476,7 @@ SyncDataList SupervisedUserSyncService::GetAllSyncData(
   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
   base::DictionaryValue* dict = update.Get();
   for (base::DictionaryValue::Iterator it(*dict); !it.IsAtEnd(); it.Advance())
-    data.push_back(CreateSyncDataFromDictionaryEntry(it.key(), it.value()));
+    data.push_back(CreateSyncDataFromDictionaryEntry(user_manager::UserID::FromUserEmail(it.key()), it.value()));
 
   return data;
 }
@@ -509,7 +510,7 @@ SyncError SupervisedUserSyncService::ProcessSyncChanges(
         // If the supervised user switched from unacknowledged to acknowledged,
         // we might need to continue with a registration.
         if (old_value && !old_value->HasKey(kAcknowledged))
-          NotifySupervisedUserAcknowledged(supervised_user.id());
+          NotifySupervisedUserAcknowledged(user_manager::UserID::FromUserEmail(supervised_user.id()));
 
         base::DictionaryValue* value = new base::DictionaryValue;
         value->SetString(kName, supervised_user.name());
@@ -551,7 +552,7 @@ void SupervisedUserSyncService::GoogleSignedOut(
 }
 
 void SupervisedUserSyncService::NotifySupervisedUserAcknowledged(
-    const std::string& supervised_user_id) {
+    const user_manager::UserID& supervised_user_id) {
   FOR_EACH_OBSERVER(SupervisedUserSyncServiceObserver, observers_,
                     OnSupervisedUserAcknowledged(supervised_user_id));
 }