Don't enforce signin for the settings app.

The main use of the settings app is to switch profiles in the app
when you are signed out. For this to be useful it is important that the
sign in enforcement does not happen for the settings app.

BUG=347025

Review URL: https://codereview.chromium.org/190143003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255881 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/extensions/application_launch.cc

@@ -345,7 +345,8 @@ WebContents* OpenEnabledApplication(const AppLaunchParams& params) {
 #if !defined(OS_CHROMEOS)
     SigninManager* signin_manager =
         SigninManagerFactory::GetForProfile(profile);
-    if (signin_manager && signin_manager->GetAuthenticatedUsername().empty()) {
+    if (extension->id() != extension_misc::kSettingsAppId &&
+        signin_manager && signin_manager->GetAuthenticatedUsername().empty()) {
       const char kEnforceSigninToUseAppsFieldTrial[] = "EnforceSigninToUseApps";
 
       std::string field_trial_value =