Migrate tab discard exceptions pref to include time

On startup, the old list pref is migrated to the new dict pref and the
old pref is cleared. Currently for all old entries, we set the
timestamp to the current time. This will ensure that as time passes we
will clear less extra old entries.

Bug: 1513455
Change-Id: I73582030a042f82cbe39d9c483cfe08de5d2bf8e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5170306
Reviewed-by: John Lee <[email protected]>
Reviewed-by: Jeffrey Young <[email protected]>
Commit-Queue: Alison Gale <[email protected]>
Reviewed-by: Christian Dullweber <[email protected]>
Reviewed-by: Joe Mason <[email protected]>
Reviewed-by: Dominic Battre <[email protected]>
Code-Coverage: [email protected] <[email protected]>
Reviewed-by: Rushan Suleymanov <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1251480}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index ea4e5dcb..bd5fed1d 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -2617,6 +2617,12 @@
   profile_prefs->ClearPref(kBorealisVmTokenHash);
 #endif  // BUILDFLAG(IS_CHROMEOS_ASH)
 
+#if !BUILDFLAG(IS_ANDROID)
+  // Deprecated 1/2024.
+  performance_manager::user_tuning::prefs::MigrateTabDiscardingExceptionsPref(
+      profile_prefs);
+#endif
+
   // Please don't delete the following line. It is used by PRESUBMIT.py.
   // END_MIGRATE_OBSOLETE_PROFILE_PREFS