Fix Arc integration test.

chrome/browser/chromeos/profiles/profile_helper.cc

Index: chrome/browser/chromeos/profiles/profile_helper.cc
diff --git a/chrome/browser/chromeos/profiles/profile_helper.cc b/chrome/browser/chromeos/profiles/profile_helper.cc
index bb90818647f3a1271b15a645ba1931c58c5389d5..a9677ec0a5fb88be613c352cf9488ae9d516dc72 100644
--- a/chrome/browser/chromeos/profiles/profile_helper.cc
+++ b/chrome/browser/chromeos/profiles/profile_helper.cc
@@ -342,7 +342,6 @@ const user_manager::User* ProfileHelper::GetUserByProfile(
       if ((*it)->GetAccountId().GetUserEmail() == user_name)
         return *it;
     }
-
     // In case of test setup we should always default to primary user.
     return user_manager::UserManager::Get()->GetPrimaryUser();
   }
@@ -467,6 +466,10 @@ void ProfileHelper::RemoveUserFromListForTesting(const AccountId& account_id) {
     user_list_for_testing_.erase(it);
 }
 
+void ProfileHelper::ClearUserToProfileMappingForTesting() {

[lgcheng, 2017/02/22 23:36:44]

In Arc sync integration tests, users(not browser_test base user, sync test user
added in setupService) are destroyed without notify this field thus lead to
shutdown crash.  

+  user_list_for_testing_.clear();
+}
+
 // static
 std::string ProfileHelper::GetUserIdHashByUserIdForTesting(
     const std::string& user_id) {