Support new --arc-availability flag.

chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc

Index: chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
diff --git a/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc b/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
index f785b605d07f453dc9b4b73d0513504ee3614911..2258210a26e61a94475a75e214b5d1472944cee9 100644
--- a/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
+++ b/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
@@ -880,7 +880,13 @@ void ChromeUserManagerImpl::ArcKioskAppLoggedIn(user_manager::User* user) {
       user_manager::User::USER_IMAGE_INVALID, false);
 
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
-  command_line->AppendSwitch(chromeos::switches::kEnableArc);
+  // This works partially, because sevices calling IsArcAvailable()
+  // before Kiosk log-in does not work. This causes an issue that ARC apps
+  // may not be shown in App launcher. cf) crbug.com/685393, crbug.com/678846.
+  // TODO(hidehiko|poromov|lhchavez): Find a correct approach, then remove
+  // this.
+  command_line->AppendSwitchASCII(chromeos::switches::kArcAvailability,
+                                  "officially-supported");
   command_line->AppendSwitch(::switches::kForceAndroidAppMode);
   command_line->AppendSwitch(::switches::kSilentLaunch);