Use new sync backup DB if settings are reset to avoid undoing reset.

chrome/browser/sync/profile_sync_service.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/sync/profile_sync_service.h"
 
 #include <cstddef>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 14 matching lines @@
 #include "base/threading/thread_restrictions.h"
 #include "build/build_config.h"
 #include "chrome/browser/bookmarks/enhanced_bookmarks_features.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/browsing_data/browsing_data_helper.h"
 #include "chrome/browser/browsing_data/browsing_data_remover.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/defaults.h"
 #include "chrome/browser/invalidation/profile_invalidation_provider_factory.h"
 #include "chrome/browser/net/chrome_cookie_notification_details.h"
+#include "chrome/browser/prefs/chrome_pref_service_factory.h"
 #include "chrome/browser/prefs/pref_service_syncable.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/services/gcm/gcm_profile_service.h"
 #include "chrome/browser/services/gcm/gcm_profile_service_factory.h"
 #include "chrome/browser/signin/about_signin_internals_factory.h"
 #include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
 #include "chrome/browser/signin/signin_manager_factory.h"
 #include "chrome/browser/sync/backend_migrator.h"
 #include "chrome/browser/sync/glue/chrome_report_unrecoverable_error.h"
 #include "chrome/browser/sync/glue/device_info.h"
@@ skipping 469 matching lines @@
     credentials.scope_set.insert(signin_->GetSyncScopeToUse());
   }
 
   return credentials;
 }
 
 bool ProfileSyncService::ShouldDeleteSyncFolder() {
   if (backend_mode_ == SYNC)
     return !HasSyncSetupCompleted();
 
-  // Start fresh if it's the first time backup after user stopped syncing.
-  // This is needed because backup DB may contain items deleted by user during
-  // sync period and can cause back-from-dead issues.
-  if (backend_mode_ == BACKUP && !sync_prefs_.GetFirstSyncTime().is_null())
-    return true;
+  if (backend_mode_ == BACKUP) {
+    // Start fresh if:
+    // * It's the first time backup after user stopped syncing because backup
+    //   DB may contain items deleted by user during sync period and can cause
+    //   back-from-dead issues if user didn't choose rollback.
+    // * Settings are reset because of tampering to avoid restoring settings
+    //   from backup.
+    if (!sync_prefs_.GetFirstSyncTime().is_null() ||
+        profile_->GetStartTime() <= chrome_prefs::GetResetTime(profile_)) {

[gab, 2014/07/07 20:56:12]

Technically this will work if chrome_prefs::GetResetTime returns a NULL time as
it's internally represented as 0, but feels like a !is_null() check would be
safer (i.e., no need to even compare if there is no reset time).

+      return true;
+    }
+  }
 
   return false;
 }
 
 void ProfileSyncService::InitializeBackend(bool delete_stale_data) {
   if (!backend_) {
     NOTREACHED();
     return;
   }
 
@@ skipping 2041 matching lines @@
   }
   return result;
 }
 
 void ProfileSyncService::StartStopBackupForTesting() {
   if (backend_mode_ == BACKUP)
     ShutdownImpl(browser_sync::SyncBackendHost::STOP_AND_CLAIM_THREAD);
   else
     backup_rollback_controller_.Start(base::TimeDelta());
 }