Account Picker: fix window resize.

ui/login/account_picker/screen_account_picker.js

Index: ui/login/account_picker/screen_account_picker.js
diff --git a/ui/login/account_picker/screen_account_picker.js b/ui/login/account_picker/screen_account_picker.js
index 7cac00bc3a4131a61cced2d65def37864f3e96ef..eb9572c3c2ffcb79048fa15040919d642729c638 100644
--- a/ui/login/account_picker/screen_account_picker.js
+++ b/ui/login/account_picker/screen_account_picker.js
@@ -225,8 +225,10 @@ login.createScreen('AccountPickerScreen', 'account-picker', function() {
         bubble.style.visibility = 'hidden';
         bubble.hidden = false;
         // Now we need the bubble to have the new content before calculating
-        // size.
-        bubble.replaceContent(error);
+        // size. Undefined |error| == reuse old content.
+        if (error !== undefined)
+          bubble.replaceContent(error);
+
         // Get bubble size.
         var bubbleOffsetHeight = parseInt(bubble.offsetHeight);
         var bubbleOffsetWidth = parseInt(bubble.offsetWidth);