Make the lists in the password section flex up to 245px.

chrome/browser/resources/settings/passwords_and_forms_page/passwords_section.css

Index: chrome/browser/resources/settings/passwords_and_forms_page/passwords_section.css
diff --git a/chrome/browser/resources/settings/passwords_and_forms_page/passwords_section.css b/chrome/browser/resources/settings/passwords_and_forms_page/passwords_section.css
index 05405bea06e27624831f2f40146d9c2c1c9a513c..c11ea76d1c06be401e1603114e1bef807d9bd9c4 100644
--- a/chrome/browser/resources/settings/passwords_and_forms_page/passwords_section.css
+++ b/chrome/browser/resources/settings/passwords_and_forms_page/passwords_section.css
@@ -2,11 +2,18 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
+:host {
+  display: flex;
+  flex-direction: column;
+}
+
 iron-list {
-  /* TODO(hcarmona): Make this flex. */
-  -webkit-padding-start: 8px;
-  height: 300px;
-  padding-top: 16px;
+  -webkit-padding-start: 16px;
+  flex: 1;
+  max-height: 245px;
+  overflow: auto;
+  padding-bottom: 8px;
+  padding-top: 8px;
 }
 
 paper-icon-button {