Remove obsolete LacrosAvailability feature

Lacros is gone.

- Deprecate the LacrosAvailability policy
- Remove the remaining implementation of it, in particular
  LacrosAvailabilityPolicyHandler
- Remove "lacros-availability-ignore" switch and corresponding flag
- Retire "lacros_launch_switch local" state pref

Bug: b:365741912
Change-Id: I0f9286ef82fdd448129288a0763b40eb76f9ffed
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6010010
Reviewed-by: Devlin Cronin <[email protected]>
Reviewed-by: Igor <[email protected]>
Commit-Queue: Georg Neis <[email protected]>
Reviewed-by: Hidehiko Abe <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1397242}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 0ab75ca..7bb22c5 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -1169,6 +1169,7 @@
 const char kCryptAuthEnrollmentUserPrivateKey[] =
     "cryptauth.enrollment.user_private_key";
 const char kLacrosLaunchOnLogin[] = "lacros.launch_on_login";
+const char kLacrosLaunchSwitch[] = "lacros_launch_switch";
 #endif
 
 // Deprecated 12/2024.
@@ -1284,6 +1285,11 @@
 
   // Deprecated 11/2024.
   registry->RegisterIntegerPref(kOnDeviceModelTimeoutCount, 0);
+
+#if BUILDFLAG(IS_CHROMEOS)
+  // Deprecated 12/2024.
+  registry->RegisterIntegerPref(kLacrosLaunchSwitch, 0);
+#endif
 }
 
 // Register prefs used only for migration (clearing or moving to a new key).
@@ -2589,6 +2595,11 @@
   optimization_guide::model_execution::prefs::MigrateLegacyUsagePrefs(
       local_state);
 
+  // Added 12/2024
+#if BUILDFLAG(IS_CHROMEOS)
+  local_state->ClearPref(kLacrosLaunchSwitch);
+#endif
+
   // Please don't delete the following line. It is used by PRESUBMIT.py.
   // END_MIGRATE_OBSOLETE_LOCAL_STATE_PREFS