Remove reader mode pref.

This is part of a larger effort to remove the desktop kReaderMode flag
from the codebase.

Bug: 40258128
Change-Id: Iffc83fa63634aa89ff25f66e3ff9b89a0ae27352
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5331545
Reviewed-by: Mikel Astiz <[email protected]>
Commit-Queue: Abigail Klein <[email protected]>
Reviewed-by: Jesse Doherty <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1269199}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index ead26a8..948fc883 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -112,8 +112,6 @@
 #include "components/content_settings/core/common/pref_names.h"
 #include "components/custom_handlers/protocol_handler_registry.h"
 #include "components/dom_distiller/core/distilled_page_prefs.h"
-#include "components/dom_distiller/core/dom_distiller_features.h"
-#include "components/dom_distiller/core/pref_names.h"
 #include "components/domain_reliability/domain_reliability_prefs.h"
 #include "components/embedder_support/origin_trials/origin_trial_prefs.h"
 #include "components/enterprise/browser/identifiers/identifiers_prefs.h"
@@ -1023,6 +1021,9 @@
     "os_crypt.app_bound_fixed_data";
 #endif  // BUILDFLAG(IS_WIN)
 
+// Deprecated 02/2024.
+constexpr char kOfferReaderMode[] = "dom_distiller.offer_reader_mode";
+
 // Register local state used only for migration (clearing or moving to a new
 // key).
 void RegisterLocalStatePrefsForMigration(PrefRegistrySimple* registry) {
@@ -1448,6 +1449,9 @@
 
   // Deprecated 02/2024
   registry->RegisterBooleanPref(kResetCheckDefaultBrowser, false);
+
+  // Deprecated 02/2024.
+  registry->RegisterBooleanPref(kOfferReaderMode, false);
 }
 
 void ClearSyncRequestedPrefAndMaybeMigrate(PrefService* profile_prefs) {
@@ -1765,7 +1769,6 @@
   enterprise::RegisterIdentifiersProfilePrefs(registry);
   enterprise_reporting::RegisterProfilePrefs(registry);
   dom_distiller::DistilledPagePrefs::RegisterProfilePrefs(registry);
-  dom_distiller::RegisterProfilePrefs(registry);
   DownloadPrefs::RegisterProfilePrefs(registry);
   permissions::PermissionHatsTriggerHelper::RegisterProfilePrefs(registry);
   history_clusters::prefs::RegisterProfilePrefs(registry);
@@ -2726,6 +2729,9 @@
   // Deprecated 02/2024
   profile_prefs->ClearPref(kResetCheckDefaultBrowser);
 
+  // Deprecated 02/2024
+  profile_prefs->ClearPref(kOfferReaderMode);
+
   // Added 02/2024, but DO NOT REMOVE after the usual year!
   // TODO(crbug.com/40282890): Remove ~one year after full launch.
   browser_sync::MaybeMigrateSyncingUserToSignedIn(profile_path, profile_prefs);