Credential passing is the only way for passwords now.

chrome/browser/resources/gaia_auth_host/authenticator.js

Index: chrome/browser/resources/gaia_auth_host/authenticator.js
diff --git a/chrome/browser/resources/gaia_auth_host/authenticator.js b/chrome/browser/resources/gaia_auth_host/authenticator.js
index 99a072849c07d38078349c600498342c4a771a69..3b9f0038430c521ccdfe24aee1b17ed563ec4357 100644
--- a/chrome/browser/resources/gaia_auth_host/authenticator.js
+++ b/chrome/browser/resources/gaia_auth_host/authenticator.js
@@ -512,13 +512,10 @@ cr.define('cr.login', function() {
     var msg = e.data;
     if (msg.method == 'attemptLogin') {
       this.email_ = msg.email;
-      this.password_ = msg.password;
       this.chooseWhatToSync_ = msg.chooseWhatToSync;
       // We need to dispatch only first event, before user enters password.
-      if (!msg.password) {
-        this.dispatchEvent(
-            new CustomEvent('attemptLogin', {detail: msg.email}));
-      }
+      this.dispatchEvent(
+          new CustomEvent('attemptLogin', {detail: msg.email}));
     } else if (msg.method == 'dialogShown') {
       this.dispatchEvent(new Event('dialogShown'));
     } else if (msg.method == 'dialogHidden') {
@@ -582,13 +579,6 @@ cr.define('cr.login', function() {
       return;
     }
 
-    // TODO(achuith): Eliminate this branch when credential passing api is
-    // stable on prod. crbug.com/467778.
-    if (this.authFlow != AuthFlow.SAML) {
-      this.onAuthCompleted_();
-      return;
-    }
-
     if (this.samlHandler_.scrapedPasswordCount == 0) {
       if (this.noPasswordCallback) {
         this.noPasswordCallback(this.email_);