[desktop iOS promo] Promos utils and needed prefs

Added the promos utils folder for different utility functions that will
help with the overall promo in upcoming CLs. Also added the necessary
synced prefs, and moved the feature flag to the promos folder. The
business logic for deciding whether to show the promo or not will
be added in a subsequent CL to keep this one from becoming too large.
Created a promos folder because this is a first contextual iOS promo of
more to come for different contexts.

Bug: 1435035
Change-Id: I57fa02d0638d55da0b8b8548ea96396b0d39432d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4620435
Reviewed-by: Avi Drissman <[email protected]>
Commit-Queue: Nicolas MacBeth <[email protected]>
Reviewed-by: Gabriel Charette <[email protected]>
Reviewed-by: Marc Treib <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1160031}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 1669c97..645106f 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -287,6 +287,10 @@
 #include "components/user_notes/user_notes_prefs.h"
 #endif  // BUILDFLAG(IS_ANDROID)
 
+#if !BUILDFLAG(IS_ANDROID) && BUILDFLAG(GOOGLE_CHROME_BRANDING)
+#include "chrome/browser/promos/promos_utils.h"
+#endif  // !BUILDFLAG(IS_ANDROID) && BUILDFLAG(GOOGLE_CHROME_BRANDING)
+
 #if BUILDFLAG(IS_CHROMEOS)
 #include "chrome/browser/apps/intent_helper/supported_links_infobar_prefs_service.h"
 #include "chrome/browser/chromeos/extensions/echo_private/echo_private_api.h"
@@ -1616,6 +1620,10 @@
   omnibox::RegisterProfilePrefs(registry);
   ZeroSuggestProvider::RegisterProfilePrefs(registry);
 
+#if !BUILDFLAG(IS_ANDROID) && BUILDFLAG(GOOGLE_CHROME_BRANDING)
+  promos_utils::RegisterProfilePrefs(registry);
+#endif  // !BUILDFLAG(IS_ANDROID) && BUILDFLAG(GOOGLE_CHROME_BRANDING)
+
 #if BUILDFLAG(ENABLE_SESSION_SERVICE)
   RegisterSessionServiceLogProfilePrefs(registry);
   SessionDataService::RegisterProfilePrefs(registry);