Enable BlockUniversalLinksInOffTheRecord by default.

Bug: 861752
Change-Id: Ie6cb88165e5aa4131ab6c387ff81017cca67eec4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1539872
Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Auto-Submit: Mike Dougherty <michaeldo@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644470}

ios/web/features.mm

@@ -41,7 +41,7 @@ const base::Feature kHistoryClobberWorkaround{
     "WKWebViewHistoryClobberWorkaround", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kBlockUniversalLinksInOffTheRecordMode{
-    "BlockUniversalLinksInOffTheRecord", base::FEATURE_DISABLED_BY_DEFAULT};
+    "BlockUniversalLinksInOffTheRecord", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kWebUISchemeHandling{"WebUISchemeHandling",
                                          base::FEATURE_DISABLED_BY_DEFAULT};