Accessibility OOBE screen can be too tall with feature flag.

With --enable-experimental-accessiblity-features, too many a11y tools
are included in the OOBE screen and it flows behind the button. This
makes the accessibility tools list scroll.

Bug: 833047
Change-Id: If5ca4ee1dea324b883e97195a6debad5f0804ed7
Reviewed-on: https://chromium-review.googlesource.com/1194982Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Commit-Queue: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587282}

chrome/browser/resources/chromeos/login/oobe_welcome.css

@@ -32,6 +32,10 @@
   border-bottom: var(--oobe-a11y-dialog-list-item-border);
 }
 
+#accessibilityScreen .scroll {
+  overflow: scroll;
+}
+
 /************* Timezone Screen **************/
 #timezoneScreen .timezone-selection-entry {
   border-top: var(--oobe-dialog-list-item-border);

chrome/browser/resources/chromeos/login/oobe_welcome.html

@@ -120,7 +120,7 @@
       <div slot="subtitle">
         [[i18nDynamic(locale, 'accessibilitySectionHint')]]
       </div>
-      <div slot="footer" class="layout vertical">
+      <div slot="footer" class="layout vertical scroll">
         <oobe-a11y-option checked="[[a11yStatus.spokenFeedbackEnabled]]"
             on-change="onA11yOptionChanged_"
             chrome-message="enableSpokenFeedback"