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 {

[gab, 2015/08/24 21:48:45]

rm this enum

[sdefresne, 2015/08/25 08:36:10]

Done.

   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;
@@ skipping 27 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();

[gab, 2015/08/24 21:48:45]

Cross-referencing with https://codereview.chromium.org/24930003 which introduced
this code, looks like time.h and histograms.h were added then and that this was
still there only use in this file to this day so they can be removed.

[sdefresne, 2015/08/25 08:36:10]

Done.

-    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() {}