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

chrome/browser/prefs/session_startup_pref.cc

 // Copyright (c) 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/session_startup_pref.h"
 
 #include <string>
 
-#include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
-#include "base/time/time.h"
 #include "base/values.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/pref_names.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/url_formatter/url_fixer.h"
 
 namespace {
 
-enum StartupURLsMigrationMetrics {
-  STARTUP_URLS_MIGRATION_METRICS_PERFORMED,
-  STARTUP_URLS_MIGRATION_METRICS_NOT_PRESENT,
-  STARTUP_URLS_MIGRATION_METRICS_RESET,
-  STARTUP_URLS_MIGRATION_METRICS_MAX,
-};
-
 // Converts a SessionStartupPref::Type to an integer written to prefs.
 int TypeToPrefValue(SessionStartupPref::Type type) {
   switch (type) {
     case SessionStartupPref::LAST: return SessionStartupPref::kPrefValueLast;
     case SessionStartupPref::URLS: return SessionStartupPref::kPrefValueURLs;
     default:                       return SessionStartupPref::kPrefValueNewTab;
   }
 }
 
 void SetNewURLList(PrefService* prefs) {
@@ skipping 21 matching lines @@
 
 // static
 void SessionStartupPref::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   registry->RegisterIntegerPref(
       prefs::kRestoreOnStartup,
       TypeToPrefValue(GetDefaultStartupType()),
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
   registry->RegisterListPref(prefs::kURLsToRestoreOnStartup,
                              user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
-  registry->RegisterListPref(prefs::kURLsToRestoreOnStartupOld);
   registry->RegisterBooleanPref(prefs::kRestoreOnStartupMigrated, false);
-  registry->RegisterInt64Pref(prefs::kRestoreStartupURLsMigrationTime, false);
 }
 
 // static
 SessionStartupPref::Type SessionStartupPref::GetDefaultStartupType() {
 #if defined(OS_CHROMEOS)
   return SessionStartupPref::LAST;
 #else
   return SessionStartupPref::DEFAULT;
 #endif
 }
@@ skipping 49 matching lines @@
   const base::ListValue* url_list =
       prefs->GetList(prefs::kURLsToRestoreOnStartup);
   URLListToPref(url_list, &pref);
 
   return pref;
 }
 
 // static
 void SessionStartupPref::MigrateIfNecessary(PrefService* prefs) {
   DCHECK(prefs);
-
-  // Check if we need to migrate the old version of the startup URLs preference
-  // to the new name, and also send metrics about the migration.
-  StartupURLsMigrationMetrics metrics_result =
-      STARTUP_URLS_MIGRATION_METRICS_MAX;
-  const base::ListValue* old_startup_urls =
-      prefs->GetList(prefs::kURLsToRestoreOnStartupOld);
-  if (!prefs->GetUserPrefValue(prefs::kRestoreStartupURLsMigrationTime)) {
-    // Record the absence of the migration timestamp, this will get overwritten
-    // below if migration occurs now.
-    metrics_result = STARTUP_URLS_MIGRATION_METRICS_NOT_PRESENT;
-
-    // Seems like we never migrated, do it if necessary.
-    if (!prefs->GetUserPrefValue(prefs::kURLsToRestoreOnStartup)) {
-      if (old_startup_urls && !old_startup_urls->empty()) {
-        prefs->Set(prefs::kURLsToRestoreOnStartup, *old_startup_urls);
-        prefs->ClearPref(prefs::kURLsToRestoreOnStartupOld);
-      }
-      metrics_result = STARTUP_URLS_MIGRATION_METRICS_PERFORMED;
-    }
-
-    prefs->SetInt64(prefs::kRestoreStartupURLsMigrationTime,
-                    base::Time::Now().ToInternalValue());
-  } else if (old_startup_urls && !old_startup_urls->empty()) {
-    // Migration needs to be reset.
-    prefs->ClearPref(prefs::kURLsToRestoreOnStartupOld);
-    base::Time last_migration_time = base::Time::FromInternalValue(
-        prefs->GetInt64(prefs::kRestoreStartupURLsMigrationTime));
-    base::Time now = base::Time::Now();
-    prefs->SetInt64(prefs::kRestoreStartupURLsMigrationTime,
-                    now.ToInternalValue());
-    if (now < last_migration_time)
-      last_migration_time = now;
-    UMA_HISTOGRAM_CUSTOM_TIMES("Settings.StartupURLsResetTime",
-                               now - last_migration_time,
-                               base::TimeDelta::FromDays(0),
-                               base::TimeDelta::FromDays(7),
-                               50);
-    metrics_result = STARTUP_URLS_MIGRATION_METRICS_RESET;
-  }
-
-  // Record a metric migration event if something interesting happened.
-  if (metrics_result != STARTUP_URLS_MIGRATION_METRICS_MAX) {
-    UMA_HISTOGRAM_ENUMERATION(
-          "Settings.StartupURLsMigration",
-          metrics_result,
-          STARTUP_URLS_MIGRATION_METRICS_MAX);
-  }
-
   if (!prefs->GetBoolean(prefs::kRestoreOnStartupMigrated)) {
     // Read existing values.
     const base::Value* homepage_is_new_tab_page_value =
         prefs->GetUserPrefValue(prefs::kHomePageIsNewTabPage);
     bool homepage_is_new_tab_page = true;
     if (homepage_is_new_tab_page_value) {
       if (!homepage_is_new_tab_page_value->GetAsBoolean(
               &homepage_is_new_tab_page))
         NOTREACHED();
     }
@@ skipping 64 matching lines @@
     case kPrefValueLast:     return SessionStartupPref::LAST;
     case kPrefValueURLs:     return SessionStartupPref::URLS;
     case kPrefValueHomePage: return SessionStartupPref::HOMEPAGE;
     default:                 return SessionStartupPref::DEFAULT;
   }
 }
 
 SessionStartupPref::SessionStartupPref(Type type) : type(type) {}
 
 SessionStartupPref::~SessionStartupPref() {}