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

chrome/browser/prefs/browser_prefs.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/prefs/browser_prefs.h"
 
 #include <string>
 
 #include "base/metrics/histogram_macros.h"
 #include "base/prefs/pref_registry_simple.h"
@@ skipping 224 matching lines @@
 
 // The SessionStartupPref used this pref to store the list of URLs to restore
 // on startup, and then renamed it to "sessions.startup_urls" in M31. Migration
 // code was added and the timestamp of when the migration happened was tracked
 // by "session.startup_urls_migration_time". Both are obsolete now (12/2015) and
 // should be removed once a few releases have happened.
 const char kURLsToRestoreOnStartupOld[] = "session.urls_to_restore_on_startup";
 const char kRestoreStartupURLsMigrationTime[] =
   "session.startup_urls_migration_time";
 
+// Deprecated 12/2015.
+const char kRestoreOnStartupMigrated[] = "session.restore_on_startup_migrated";
+
 }  // namespace
 
 namespace chrome {
 
 void RegisterLocalState(PrefRegistrySimple* registry) {
   // Please keep this list alphabetized.
   AppListService::RegisterPrefs(registry);
   browser_shutdown::RegisterPrefs(registry);
   BrowserProcessImpl::RegisterPrefs(registry);
   ChromeMetricsServiceClient::RegisterPrefs(registry);
@@ skipping 280 matching lines @@
 
   // Preferences registered only for migration (clearing or moving to a new key)
   // go here.
 
 #if defined(OS_WIN)
   registry->RegisterIntegerPref(kShownAutoLaunchInfobarDeprecated, 0);
 #endif  // defined(OS_WIN)
 
   registry->RegisterListPref(kURLsToRestoreOnStartupOld);
   registry->RegisterInt64Pref(kRestoreStartupURLsMigrationTime, 0);
+  registry->RegisterBooleanPref(kRestoreOnStartupMigrated, false);
 }
 
 void RegisterUserProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
   RegisterProfilePrefs(registry);
 
 #if defined(OS_CHROMEOS)
   chromeos::PowerPrefs::RegisterUserProfilePrefs(registry);
 #endif
 }
 
@@ skipping 31 matching lines @@
 #endif
 
 #if defined(OS_WIN)
   // Added 11/2015.
   profile_prefs->ClearPref(kShownAutoLaunchInfobarDeprecated);
 #endif
 
   // Added 12/1015.
   profile_prefs->ClearPref(kURLsToRestoreOnStartupOld);
   profile_prefs->ClearPref(kRestoreStartupURLsMigrationTime);
+
+  // Added 12/2015.
+  profile_prefs->ClearPref(kRestoreOnStartupMigrated);
 }
 
 }  // namespace chrome