Remove migration of obsolete value for "session.restore_on_startup".

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 6db1e3da224eac813b0bb04f7aa95afad63cf3a9..60fd0509b66090f49b8ed1f2942fcef2feea834b 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -57,7 +57,7 @@ const char kSessionExitedCleanly[] = "profile.exited_cleanly";
 const char kSessionExitType[] = "profile.exit_type";
 
 // An integer pref. Holds one of several values:
-// 0: (deprecated) open the homepage on startup.
+// 0: unused, previously indicated to open the homepage on startup.
 // 1: restore the last session.
 // 2: this was used to indicate a specific session should be restored. It is
 //    no longer used, but saved to avoid conflict with old preferences.
@@ -66,12 +66,6 @@ const char kSessionExitType[] = "profile.exit_type";
 // 5: open the New Tab Page on startup.
 const char kRestoreOnStartup[] = "session.restore_on_startup";
 
-// A preference to keep track of whether we have already checked whether we
-// need to migrate the user from kRestoreOnStartup=0 to kRestoreOnStartup=4.
-// We only need to do this check once, on upgrade from m18 or lower to m19 or
-// higher.
-const char kRestoreOnStartupMigrated[] = "session.restore_on_startup_migrated";
-
 // The URLs to restore on startup or when the home button is pressed. The URLs
 // are only restored on startup if kRestoreOnStartup is 4.
 const char kURLsToRestoreOnStartup[] = "session.startup_urls";