| Index: chrome/browser/profiles/profiles_state.cc | 
| diff --git a/chrome/browser/profiles/profiles_state.cc b/chrome/browser/profiles/profiles_state.cc | 
| index dd532c29ca79870b9dabf2034715279e6a402f1f..85a465fa4e06f1f017be921bd010a1d504534904 100644 | 
| --- a/chrome/browser/profiles/profiles_state.cc | 
| +++ b/chrome/browser/profiles/profiles_state.cc | 
| @@ -193,8 +193,10 @@ bool SetActiveProfileToGuestIfLocked() { | 
|  | 
| const ProfileInfoCache& cache = profile_manager->GetProfileInfoCache(); | 
| size_t index = cache.GetIndexOfProfileWithPath(active_profile_path); | 
| -  if (!cache.ProfileIsSigninRequiredAtIndex(index)) | 
| +  if (index == std::string::npos || | 
| +      !cache.ProfileIsSigninRequiredAtIndex(index)) { | 
| return false; | 
| +  } | 
|  | 
| PrefService* local_state = g_browser_process->local_state(); | 
| DCHECK(local_state); | 
|  |