Introduce the PlatformNotificationContext class.

content/browser/notifications/notification_database.cc

 // Copyright 2015 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 "content/browser/notifications/notification_database.h"
 
 #include <string>
 
 #include "base/files/file_util.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 50 matching lines @@
                             kDataKeyPrefix,
                             storage::GetIdentifierFromOrigin(origin).c_str(),
                             kKeySeparator,
                             base::Int64ToString(notification_id).c_str());
 }
 
 }  // namespace
 
 NotificationDatabase::NotificationDatabase(const base::FilePath& path)
     : path_(path) {
-  sequence_checker_.DetachFromSequence();
 }
 
 NotificationDatabase::~NotificationDatabase() {
   DCHECK(sequence_checker_.CalledOnValidSequencedThread());
 }
 
 NotificationDatabase::Status NotificationDatabase::Open(
     bool create_if_missing) {
   DCHECK(sequence_checker_.CalledOnValidSequencedThread());
   DCHECK_EQ(STATE_UNINITIALIZED, state_);
@@ skipping 129 matching lines @@
 
   if (!base::StringToInt64(value, &next_notification_id_) ||
       next_notification_id_ < kFirstNotificationId) {
     return STATUS_ERROR_CORRUPTED;
   }
 
   return STATUS_OK;
 }
 
 }  // namespace content