Prevent arrangement section from causing content blink

- This CL delays the rendering of the arrangement section until
|displays| is truthy to avoid the arrangement section flashing.


Bug: 1022315
Change-Id: I36da215142ed8bafb739dbbdedaf9bfa4f2baf24
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1979115Reviewed-by: James Hawkins <jhawkins@chromium.org>
Reviewed-by: Bailey Berro <baileyberro@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: James Hawkins <jhawkins@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727657}

chrome/browser/resources/settings/chromeos/device_page/display.js

@@ -1027,6 +1027,9 @@ Polymer({
    * @private
    */
   shouldShowArrangementSection_: function() {
+    if (!this.displays) {
+      return false;
+    }
     return this.hasMultipleDisplays_() || this.isMirrored_(this.displays);
   },