arc: Implement safe access to ArcAuthService.

chrome/browser/chromeos/arc/arc_auth_service.cc

Index: chrome/browser/chromeos/arc/arc_auth_service.cc
diff --git a/chrome/browser/chromeos/arc/arc_auth_service.cc b/chrome/browser/chromeos/arc/arc_auth_service.cc
index b9e6986c54d8648191e565c52f478c4d283041e0..93daf031664f19e2af0311b970f978b5acf57060 100644
--- a/chrome/browser/chromeos/arc/arc_auth_service.cc
+++ b/chrome/browser/chromeos/arc/arc_auth_service.cc
@@ -342,9 +342,6 @@ void ArcAuthService::OnPrimaryUserProfilePrepared(Profile* profile) {
 
   Shutdown();
 
-  profile_ = profile;
-  SetState(State::STOPPED);
-
   if (!IsAllowedForProfile(profile))
     return;
 
@@ -354,6 +351,9 @@ void ArcAuthService::OnPrimaryUserProfilePrepared(Profile* profile) {
     return;
   }
 
+  profile_ = profile;
+  SetState(State::STOPPED);
+
   PrefServiceSyncableFromProfile(profile_)->AddSyncedPrefObserver(
       prefs::kArcEnabled, this);
 
@@ -637,6 +637,9 @@ bool ArcAuthService::IsArcManaged() const {
 
 bool ArcAuthService::IsArcEnabled() const {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  if (!IsAllowed())
+    return false;
+
   DCHECK(profile_);
   return profile_->GetPrefs()->GetBoolean(prefs::kArcEnabled);
 }