Fix background color of password entry field in user pods

The password entry field in user pods should always have a white
background color, even if it is disabled.

BUG=396008
TEST=Manual

Review URL: https://codereview.chromium.org/409093002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@285583 0039d316-1c4b-4281-b951-d872f2087c98

ui/login/account_picker/user_pod_row.css

@@ -176,6 +176,7 @@ html[dir=rtl] .main-pane {
 }
 
 .pod input[type='password'] {
+  background-color: white;
   border: none;
   padding: 4px 6px;
   position: relative;