Add enterprise escape hatch for updated GREASE

This change will likely be removed once the new algorithm is
confirmed to be safe.

Bug: 1261908
Change-Id: Idb1ffafe0730b6460a8328ce61c70166569d20d8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3251184
Commit-Queue: Matt Reichhoff <[email protected]>
Reviewed-by: Josh Horwich <[email protected]>
Reviewed-by: Colin Blundell <[email protected]>
Reviewed-by: Robbie McElrath <[email protected]>
Reviewed-by: Julian Pastarmov <[email protected]>
Cr-Commit-Position: refs/heads/main@{#937500}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 05341cd..0873f31a 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -958,6 +958,8 @@
       policy::policy_prefs::kTargetBlankImpliesNoOpener, true);
   registry->RegisterBooleanPref(
       policy::policy_prefs::kWebSQLInThirdPartyContextEnabled, false);
+  registry->RegisterBooleanPref(
+      policy::policy_prefs::kUserAgentClientHintsGREASEUpdateEnabled, true);
 #if defined(OS_ANDROID)
   registry->RegisterBooleanPref(policy::policy_prefs::kBackForwardCacheEnabled,
                                 true);