Add brave_page_visibility.js to provide our own pageVisibility setting

app/brave_generated_resources.grd

@@ -84,6 +84,7 @@
     <includes>
       <include name="IDR_BRAVE_TAG_SERVICES_POLYFILL" file="resources/js/tag_services_polyfill.js" type="BINDATA" />
       <include name="IDR_BRAVE_TAG_MANAGER_POLYFILL" file="resources/js/tag_manager_polyfill.js" type="BINDATA" />
+      <include name="IDR_SETTINGS_BRAVE_PAGE_VISIBILITY_JS" file="resources/js/brave_page_visibility.js" type="BINDATA" />
     </includes>
   </release>
 </grit>

app/resources/js/brave_page_visibility.js

@@ -0,0 +1,32 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+cr.define('settings', function() {
+  // use value defined in page_visibility.js in guest mode
+  if (loadTimeData.getBoolean('isGuest')) return;
+
+  // We need to specify values for every attribute in pageVisibility instead of
+  // only overriding specific attributes here because chromium does not
+  // explicitly define pageVisibility in page_visibility.js since polymer only
+  // notifies after a property is set.
+  // Use proxy objects here so we only need to write out the attributes we
+  // would like to hide.
+
+  const appearanceHandler = {
+    get: function(obj, prop) {
+      return prop === 'setTheme' ? false : true;
+    }
+  };
+
+  const handler = {
+    get: function(obj, prop) {
+      if (prop === 'appearance') return new Proxy({}, appearanceHandler);
+      return prop === 'a11y' ? false : true;
+    }
+  };
+
+  let proxy = new Proxy({}, handler);
+
+  return { pageVisibility: proxy };
+});

chromium_src/chrome/grit/settings_resources.h

@@ -0,0 +1,2 @@
+#include "brave/grit/brave_generated_resources.h"
+#include "gen/chrome/grit/settings_resources.h"

patches/chrome-browser-resources-settings-page_visibility.html.patch

@@ -0,0 +1,9 @@
+diff --git a/chrome/browser/resources/settings/page_visibility.html b/chrome/browser/resources/settings/page_visibility.html
+index 8ea50773be028e98aa2d4f90477a05f69f5a476e..6f8314a72295c599bdf97831436562c205509f61 100644
+--- a/chrome/browser/resources/settings/page_visibility.html
++++ b/chrome/browser/resources/settings/page_visibility.html
+@@ -1,3 +1,4 @@
+ <link rel="import" href="chrome://resources/html/cr.html">
+
+ <script src="page_visibility.js"></script>
++<script src="brave_page_visibility.js"></script>

patches/chrome-browser-ui-webui-settings-md_settings_ui.cc.patch

@@ -1,5 +1,5 @@
 diff --git a/chrome/browser/ui/webui/settings/md_settings_ui.cc b/chrome/browser/ui/webui/settings/md_settings_ui.cc
-index f8e4ae44148aa01579097d4ef373025b66dde788..dde5c9c64bdeb0091e7b7780e295b5d402d62249 100644
+index f8e4ae44148aa01579097d4ef373025b66dde788..1443b742c463e76462c1547452228975cd931946 100644
 --- a/chrome/browser/ui/webui/settings/md_settings_ui.cc
 +++ b/chrome/browser/ui/webui/settings/md_settings_ui.cc
 @@ -122,6 +122,7 @@ void MdSettingsUI::RegisterProfilePrefs(
@@ -10,3 +10,11 @@ index f8e4ae44148aa01579097d4ef373025b66dde788..dde5c9c64bdeb0091e7b7780e295b5d4
  }
 
  MdSettingsUI::MdSettingsUI(content::WebUI* web_ui)
+@@ -341,6 +342,7 @@ MdSettingsUI::MdSettingsUI(content::WebUI* web_ui)
+     html_source->AddResourcePath(kSettingsResources[i].name,
+                                  kSettingsResources[i].value);
+   }
++  html_source->AddResourcePath("brave_page_visibility.js", IDR_SETTINGS_BRAVE_PAGE_VISIBILITY_JS);
+   html_source->SetDefaultResource(IDR_SETTINGS_SETTINGS_HTML);
+ #endif
+