Fix focusing during OOBE

Fix a11y focus-related issues on Marketing opt-in and EULA screens.

Bug: 1024092
Change-Id: Ic976091e42ed2c46324445288e2c2b794d87883e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2401659
Commit-Queue: Denis Kuznetsov [CET] <antrim@chromium.org>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805694}

chrome/browser/resources/chromeos/login/marketing_opt_in.js

@@ -59,6 +59,7 @@ Polymer({
   /** Called when dialog is shown */
   onBeforeShow() {
     this.isAccessibilitySettingsShown_ = false;
+    this.$.marketingOptInOverviewDialog.show();
   },
 
   /**

chrome/browser/resources/chromeos/login/oobe_eula.js

@@ -335,6 +335,7 @@ Polymer({
   onFrameLoad_() {
     this.acceptButtonDisabled = false;
     this.eulaLoadingScreenShown = false;
+    this.focus();
     this.$.eulaDialog.scrollToBottom();
   },