Create Prefs for TPCD Metadata cohort

This CL adds a pref within the local state (client level) prefs store to
be shared across profiles.

Details: https://docs.google.com/document/d/1mlyJ79UZOhoU2HecfcJIqkoMaGuYrYYtCKr2OnlQyDo/edit?usp=sharing - go/sgac

bug: b:332423626
Change-Id: I44cc052fb3d6b81b0ddec3f6a995be3032647fe9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5445323
Reviewed-by: Matt Mueller <[email protected]>
Reviewed-by: Anton Maliev <[email protected]>
Commit-Queue: Jonathan Njeunje <[email protected]>
Reviewed-by: Dominic Battre <[email protected]>
Reviewed-by: Christian Dullweber <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1288684}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index aa24c2d..2785684 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -177,6 +177,7 @@
 #include "components/sync_device_info/device_info_prefs.h"
 #include "components/sync_preferences/pref_service_syncable.h"
 #include "components/sync_sessions/session_sync_prefs.h"
+#include "components/tpcd/metadata/prefs.h"
 #include "components/tracing/common/pref_names.h"
 #include "components/translate/core/browser/translate_prefs.h"
 #include "components/update_client/update_client.h"
@@ -1574,6 +1575,7 @@
           .filter_tag);
   SystemNetworkContextManager::RegisterPrefs(registry);
   tpcd::experiment::RegisterLocalStatePrefs(registry);
+  tpcd::metadata::RegisterLocalStatePrefs(registry);
   tracing::RegisterPrefs(registry);
   update_client::RegisterPrefs(registry);
   variations::VariationsService::RegisterPrefs(registry);