Revert of This CL replaces user_manager::UserID with AccountId.

ash/system/user/tray_user.cc

Index: ash/system/user/tray_user.cc
diff --git a/ash/system/user/tray_user.cc b/ash/system/user/tray_user.cc
index 06d18233d8cf033346d37645d9c6fb64924b2e60..fd101e7bed26b41d998761ff538456b7b569c6fb 100644
--- a/ash/system/user/tray_user.cc
+++ b/ash/system/user/tray_user.cc
@@ -20,7 +20,6 @@
 #include "ash/system/user/user_view.h"
 #include "base/logging.h"
 #include "base/strings/string16.h"
-#include "components/signin/core/account_id/account_id.h"
 #include "components/user_manager/user_info.h"
 #include "grit/ash_strings.h"
 #include "ui/aura/window.h"
@@ -113,13 +112,13 @@
 }
 
 views::View* TrayUser::CreateDetailedView(user::LoginStatus status) {
-  const AccountId account_id = Shell::GetInstance()
-                                   ->session_state_delegate()
-                                   ->GetUserInfo(0)
-                                   ->GetAccountId();
+  std::string user_id = Shell::GetInstance()
+                            ->session_state_delegate()
+                            ->GetUserInfo(0)
+                            ->GetUserID();
   tray::UserAccountsDelegate* delegate =
       Shell::GetInstance()->system_tray_delegate()->GetUserAccountsDelegate(
-          account_id.GetUserEmail());
+          user_id);
   if (!delegate)
     return nullptr;
   return new tray::AccountsDetailedView(this, status, delegate);