Safety check UI: separate visibility + hide in guest mode

* Defines a separate visibility for safety check.
* Hides safety check in guest mode.

Bug: 1015841,1073023
Change-Id: I07990d36b90de2a0798499ee1098cb72325287ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2159241Reviewed-by: Esmael Elmoslimany <aee@chromium.org>
Reviewed-by: Martin Šrámek <msramek@chromium.org>
Commit-Queue: Rainhard Findling <rainhard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760977}

chrome/browser/resources/settings/basic_page/basic_page.html

@@ -127,7 +127,7 @@
           </settings-section>
         </template>
         <template is="dom-if" if="[[showSafetyCheckPage_(
-            pageVisibility.privacy)]]" restamp>
+            pageVisibility.safetyCheck)]]" restamp>
           <settings-section page-title="$i18n{safetyCheckSectionTitle}"
               section="safetyCheck"
               id="safetyCheckSettingsSection">

chrome/browser/resources/settings/page_visibility.js

@@ -58,6 +58,7 @@ cr.define('settings', function() {
       privacy: false,
       onStartup: false,
       reset: false,
+      safetyCheck: false,
       appearance: false,
       defaultBrowser: false,
       advancedSettings: false,
@@ -72,6 +73,7 @@ cr.define('settings', function() {
       people: false,
       onStartup: false,
       reset: false,
+      safetyCheck: false,
       appearance: {
         setTheme: false,
         homeButton: false,
@@ -99,6 +101,7 @@ cr.define('settings', function() {
       people: true,
       onStartup: true,
       reset: true,
+      safetyCheck: true,
       appearance: {
         setTheme: true,
         homeButton: true,