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

chrome/browser/signin/easy_unlock_app_manager.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/signin/easy_unlock_app_manager.h"
 
 #include "base/command_line.h"
 #include "base/location.h"
 #include "chrome/browser/extensions/component_loader.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/ui/extensions/application_launch.h"
 #include "chrome/common/extensions/api/easy_unlock_private.h"
 #include "chrome/common/extensions/api/screenlock_private.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "components/proximity_auth/switches.h"
+#include "components/user_manager/user_id.h"
 #include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/common/one_shot_event.h"
 
 #if defined(OS_CHROMEOS)
 #include "base/sys_info.h"
 #endif
 
 namespace {
 
 class EasyUnlockAppManagerImpl : public EasyUnlockAppManager {
  public:
   EasyUnlockAppManagerImpl(extensions::ExtensionSystem* extension_system,
                            int manifest_id,
                            const base::FilePath& app_path);
   ~EasyUnlockAppManagerImpl() override;
 
   // EasyUnlockAppManager overrides.
   void EnsureReady(const base::Closure& ready_callback) override;
   void LaunchSetup() override;
   void LoadApp() override;
   void DisableAppIfLoaded() override;
   void ReloadApp() override;
-  bool SendUserUpdatedEvent(const std::string& user_id,
+  bool SendUserUpdatedEvent(const user_manager::UserID& user_id,
                             bool is_logged_in,
                             bool data_ready) override;
   bool SendAuthAttemptEvent() override;
 
  private:
   extensions::ExtensionSystem* extension_system_;
 
   // The Easy Unlock app id.
   std::string app_id_;
   int manifest_id_;
@@ skipping 78 matching lines @@
   ExtensionService* extension_service = extension_system_->extension_service();
   if (!extension_service)
     return;
 
   if (!extension_service->component_loader()->Exists(app_id_))
     return;
 
   extension_service->ReloadExtension(app_id_);
 }
 
-bool EasyUnlockAppManagerImpl::SendUserUpdatedEvent(const std::string& user_id,
+bool EasyUnlockAppManagerImpl::SendUserUpdatedEvent(const user_manager::UserID& user_id,
                                                     bool is_logged_in,
                                                     bool data_ready) {
   extensions::EventRouter* event_router = extension_system_->event_router();
   if (!event_router)
     return false;
 
   std::string event_name =
       extensions::api::easy_unlock_private::OnUserInfoUpdated::kEventName;
 
   if (!event_router->ExtensionHasEventListener(app_id_, event_name))
@@ skipping 44 matching lines @@
 }
 
 // static
 scoped_ptr<EasyUnlockAppManager> EasyUnlockAppManager::Create(
     extensions::ExtensionSystem* extension_system,
     int manifest_id,
     const base::FilePath& app_path) {
   return scoped_ptr<EasyUnlockAppManager>(
       new EasyUnlockAppManagerImpl(extension_system, manifest_id, app_path));
 }