Show login ui for login requests from ARC for child users

This cl ensures that the EDUCoexistence login ui is shown
when the request for login comes from ARC++.

Bug: 1118198
Change-Id: I04632fbf9d83ca2a9710f2fe5e014b2e16e9a865
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2364973
Commit-Queue: Yilkal Abe <yilkal@chromium.org>
Reviewed-by: Aga Wronska <agawronska@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Anastasiia N <anastasiian@chromium.org>
Reviewed-by: Kush Sinha <sinhak@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800606}

chrome/browser/ui/webui/signin/inline_login_dialog_chromeos.cc

@@ -13,6 +13,7 @@
 #include "base/json/json_writer.h"
 #include "base/macros.h"
 #include "base/metrics/histogram_functions.h"
+#include "chrome/browser/chromeos/arc/arc_util.h"
 #include "chrome/browser/chromeos/profiles/profile_helper.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/webui/chromeos/system_web_dialog_delegate.h"
@@ -83,7 +84,8 @@ GURL GetInlineLoginUrl(const std::string& email,
   }
   // User type is Child.
   if (!features::IsEduCoexistenceEnabled() ||
-      source == InlineLoginDialogChromeOS::Source::kArc) {
+      (!arc::IsSecondaryAccountForChildEnabled() &&
+       source == InlineLoginDialogChromeOS::Source::kArc)) {
     return GURL(chrome::kChromeUIAccountManagerErrorURL);
   }
   return GetUrlWithEmailParam(chrome::kChromeUIEDUCoexistenceLoginURL, email);