Remove year+ old migration support of "session.urls_to_restore_on_startup".

chrome/browser/prefs/pref_model_associator.h

Index: chrome/browser/prefs/pref_model_associator.h
diff --git a/chrome/browser/prefs/pref_model_associator.h b/chrome/browser/prefs/pref_model_associator.h
index dcfed0ea2c9eb10ff5a76e45f94b5f52273df705..fa44bc9c20d08e15117de9c544ac3c984ea544c5 100644
--- a/chrome/browser/prefs/pref_model_associator.h
+++ b/chrome/browser/prefs/pref_model_associator.h
@@ -117,26 +117,18 @@ class PrefModelAssociator
   // with ours and append a new UPDATE SyncChange to |sync_changes|. If
   // sync_pref is not set, we append an ADD SyncChange to |sync_changes| with
   // the current preference data.
-  // |migrated_preference_list| points to a vector that may be updated with a
-  // string containing the old name of the preference described by |pref_name|.
   // Note: We do not modify the sync data for preferences that are either
   // controlled by policy (are not user modifiable) or have their default value
   // (are not user controlled).
   void InitPrefAndAssociate(const syncer::SyncData& sync_pref,
                             const std::string& pref_name,
-                            syncer::SyncChangeList* sync_changes,
-                            SyncDataMap* migrated_preference_list);
+                            syncer::SyncChangeList* sync_changes);
 
   static base::Value* MergeListValues(
       const base::Value& from_value, const base::Value& to_value);
   static base::Value* MergeDictionaryValues(const base::Value& from_value,
                                             const base::Value& to_value);
 
-  // Returns whether a given preference name is a new name of a migrated
-  // preference. Exposed here for testing.
-  static bool IsMigratedPreference(const char* preference_name);
-  static bool IsOldMigratedPreference(const char* old_preference_name);
-
   // Do we have an active association between the preferences and sync models?
   // Set when start syncing, reset in StopSyncing. While this is not set, we
   // ignore any local preference changes (when we start syncing we will look