Add a policy to re-enable deprecated web platform features.

chrome/browser/ui/prefs/prefs_tab_helper.cc

Index: chrome/browser/ui/prefs/prefs_tab_helper.cc
diff --git a/chrome/browser/ui/prefs/prefs_tab_helper.cc b/chrome/browser/ui/prefs/prefs_tab_helper.cc
index 3edd66ce1ca2d521ec85f33147a2a8384250da0a..82e79d4413925f0675f358ce04bf0c39c0918e6f 100644
--- a/chrome/browser/ui/prefs/prefs_tab_helper.cc
+++ b/chrome/browser/ui/prefs/prefs_tab_helper.cc
@@ -298,6 +298,8 @@ PrefsTabHelper::PrefsTabHelper(WebContents* contents)
     pref_change_registrar_.Add(prefs::kDefaultZoomLevel, renderer_callback);
     pref_change_registrar_.Add(prefs::kEnableDoNotTrack, renderer_callback);
     pref_change_registrar_.Add(prefs::kEnableReferrers, renderer_callback);
+    pref_change_registrar_.Add(prefs::kEnableDeprecatedWebPlatformFeatures,
+                               renderer_callback);
 
 #if !defined(OS_MACOSX)
     pref_change_registrar_.Add(prefs::kFullscreenAllowed, renderer_callback);
@@ -449,6 +451,9 @@ void PrefsTabHelper::RegisterProfilePrefs(
       prefs::kDefaultCharset,
       IDS_DEFAULT_ENCODING,
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
+  registry->RegisterListPref(
+      prefs::kEnableDeprecatedWebPlatformFeatures,
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
 
   // Register font prefs that have defaults.
   std::set<std::string> fonts_with_defaults;