Add support for codepen to form_based_credentials_background

tools/telemetry/telemetry/core/browser_credentials.py

Index: tools/telemetry/telemetry/core/browser_credentials.py
diff --git a/tools/telemetry/telemetry/core/browser_credentials.py b/tools/telemetry/telemetry/core/browser_credentials.py
index d78ced98568ed79a18274462f88c0300532c5948..f64d9a70e8f9681db902182d933e97d35e4a96c8 100644
--- a/tools/telemetry/telemetry/core/browser_credentials.py
+++ b/tools/telemetry/telemetry/core/browser_credentials.py
@@ -7,6 +7,7 @@ import logging
 import os
 
 from telemetry.core import util
+from telemetry.core.backends import codepen_credentials_backend
 from telemetry.core.backends import facebook_credentials_backend
 from telemetry.core.backends import google_credentials_backend
 from telemetry.unittest import options_for_unittests
@@ -24,6 +25,7 @@ class BrowserCredentials(object):
 
     if backends is None:
       backends = [
+        codepen_credentials_backend.CodePenCredentialsBackend(),
         facebook_credentials_backend.FacebookCredentialsBackend(),
         google_credentials_backend.GoogleCredentialsBackend()]