Fix the System Profile with extensions.

chrome/browser/app_controller_mac.mm

Index: chrome/browser/app_controller_mac.mm
diff --git a/chrome/browser/app_controller_mac.mm b/chrome/browser/app_controller_mac.mm
index 91ae93205314708c7dc9ade72d85264fe460c0f9..e55eded35f245b47059a8919005373e056e5decf 100644
--- a/chrome/browser/app_controller_mac.mm
+++ b/chrome/browser/app_controller_mac.mm
@@ -1040,9 +1040,10 @@ class AppControllerProfileObserver : public ProfileInfoCacheObserver {
   NSInteger tag = [sender tag];
 
   // If there are no browser windows, and we are trying to open a browser
-  // for a locked profile, we have to show the User Manager instead as the
-  // locked profile needs authentication.
-  if (IsProfileSignedOut(lastProfile)) {
+  // for a locked profile or the system profile, we have to show the User
+  // Manager instead as the locked profile needs authentication and the system
+  // profile cannot have a browser.
+  if (IsProfileSignedOut(lastProfile) || lastProfile->IsSystemProfile()) {
     UserManager::Show(base::FilePath(),
                       profiles::USER_MANAGER_NO_TUTORIAL,
                       profiles::USER_MANAGER_SELECT_PROFILE_NO_ACTION);
@@ -1258,7 +1259,8 @@ class AppControllerProfileObserver : public ProfileInfoCacheObserver {
   // implemented as forced incognito, we can't open a new guest browser either,
   // so we have to show the User Manager as well.
   Profile* lastProfile = [self lastProfile];
-  if (lastProfile->IsGuestSession() || IsProfileSignedOut(lastProfile)) {
+  if (lastProfile->IsGuestSession() || IsProfileSignedOut(lastProfile) ||
+      lastProfile->IsSystemProfile()) {
     UserManager::Show(base::FilePath(),
                       profiles::USER_MANAGER_NO_TUTORIAL,
                       profiles::USER_MANAGER_SELECT_PROFILE_NO_ACTION);