Make sure auth error reporting handles guest mode correctly.

chrome/browser/ui/views/profiles/profile_chooser_view.cc

Index: chrome/browser/ui/views/profiles/profile_chooser_view.cc
diff --git a/chrome/browser/ui/views/profiles/profile_chooser_view.cc b/chrome/browser/ui/views/profiles/profile_chooser_view.cc
index 67f33223a1c6ec82a2327fa09ff2522d6d315730..01f317200324a357f284fc6a66789232b455a1b5 100644
--- a/chrome/browser/ui/views/profiles/profile_chooser_view.cc
+++ b/chrome/browser/ui/views/profiles/profile_chooser_view.cc
@@ -97,17 +97,20 @@ gfx::ImageSkia CreateSquarePlaceholderImage(int size) {
   return gfx::ImageSkia::CreateFrom1xBitmap(bitmap);
 }
 
+// Note that guest mode profiles won't have a token service.
+const SigninErrorController* GetSigninErrorController(Profile* profile) {
+  const ProfileOAuth2TokenService* token_service =
+      ProfileOAuth2TokenServiceFactory::GetForProfile(profile);
+  return token_service ? token_service->signin_error_controller() : NULL;
+}
+
 bool HasAuthError(Profile* profile) {
-  SigninErrorController* error =
-      ProfileOAuth2TokenServiceFactory::GetForProfile(profile)->
-          signin_error_controller();
+  const SigninErrorController* error = GetSigninErrorController(profile);
   return error && error->HasError();
 }
 
 std::string GetAuthErrorAccountId(Profile* profile) {
-  SigninErrorController* error =
-      ProfileOAuth2TokenServiceFactory::GetForProfile(profile)->
-          signin_error_controller();
+  const SigninErrorController* error = GetSigninErrorController(profile);
   if (!error)
     return std::string();
 
@@ -115,9 +118,7 @@ std::string GetAuthErrorAccountId(Profile* profile) {
 }
 
 std::string GetAuthErrorUsername(Profile* profile) {
-  SigninErrorController* error =
-      ProfileOAuth2TokenServiceFactory::GetForProfile(profile)->
-          signin_error_controller();
+  const SigninErrorController* error = GetSigninErrorController(profile);
   if (!error)
     return std::string();