Make sure key::kEnableWebBasedSignin policy also turns on command line arg

chrome/browser/policy/chrome_browser_policy_connector.cc

Index: chrome/browser/policy/chrome_browser_policy_connector.cc
diff --git a/chrome/browser/policy/chrome_browser_policy_connector.cc b/chrome/browser/policy/chrome_browser_policy_connector.cc
index e39d0109b4e24c1f16602062e3bd7edb2fb98f8e..a36e06ace762f20400d936d8d4af059d1d2cdd1c 100644
--- a/chrome/browser/policy/chrome_browser_policy_connector.cc
+++ b/chrome/browser/policy/chrome_browser_policy_connector.cc
@@ -131,9 +131,13 @@ void ChromeBrowserPolicyConnector::AppendExtraFlagPerPolicy() {
       chrome_policy.GetValue(key::kEnableWebBasedSignin);
   bool enabled = false;
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
-  if (policy_value && policy_value->GetAsBoolean(&enabled) && enabled &&
-      !command_line->HasSwitch(switches::kEnableWebBasedSignin)) {
-    command_line->AppendSwitch(switches::kEnableWebBasedSignin);
+  if (policy_value && policy_value->GetAsBoolean(&enabled) && enabled) {
+    if (!command_line->HasSwitch(switches::kEnableWebBasedSignin))
+      command_line->AppendSwitch(switches::kEnableWebBasedSignin);
+    // In M41, to fully enable web-based sign in, the kEnableIframeBasedSignin
+    // must also be specified.
+    if (!command_line->HasSwitch(switches::kEnableIframeBasedSignin))
+      command_line->AppendSwitch(switches::kEnableIframeBasedSignin);
   }
 }