Introduce the NotificationDatabase 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 "base/files/file_util.h"
+#include "content/public/browser/browser_thread.h"
+#include "third_party/leveldatabase/src/helpers/memenv/memenv.h"
+#include "third_party/leveldatabase/src/include/leveldb/db.h"
+#include "third_party/leveldatabase/src/include/leveldb/env.h"
+
+namespace content {
+namespace {
+
+// Converts the LevelDB |status| to one of the notification database's values.
+NotificationDatabase::Status LevelDBStatusToStatus(
+    const leveldb::Status& status) {
+  if (status.ok())
+    return NotificationDatabase::STATUS_OK;
+  else if (status.IsNotFound())
+    return NotificationDatabase::STATUS_ERROR_NOT_FOUND;
+
+  return NotificationDatabase::STATUS_ERROR_FAILED;
+}
+
+}  // namespace
+
+NotificationDatabase::NotificationDatabase(const base::FilePath& path)
+    : path_(path),
+      state_(STATE_UNINITIALIZED) {
+  sequence_checker_.DetachFromSequence();
+}
+
+NotificationDatabase::~NotificationDatabase() {
+  DCHECK(sequence_checker_.CalledOnValidSequencedThread());
+  db_.reset();
+}
+
+NotificationDatabase::Status NotificationDatabase::Open(
+    bool create_if_missing) {
+  DCHECK(sequence_checker_.CalledOnValidSequencedThread());
+  DCHECK_EQ(STATE_UNINITIALIZED, state_);
+
+  if (!create_if_missing) {
+    if (IsInMemoryDatabase() ||
+        !base::PathExists(path_) ||
+        base::IsDirectoryEmpty(path_)) {
+      return NotificationDatabase::STATUS_ERROR_NOT_FOUND;
+    }
+  }
+
+  leveldb::Options options;
+  options.create_if_missing = create_if_missing;
+  options.paranoid_checks = true;
+  if (IsInMemoryDatabase()) {
+    env_.reset(leveldb::NewMemEnv(leveldb::Env::Default()));
+    options.env = env_.get();
+  }
+
+  leveldb::DB* db = nullptr;
+  Status status = LevelDBStatusToStatus(
+      leveldb::DB::Open(options, path_.AsUTF8Unsafe(), &db));
+  if (status != STATUS_OK)
+    return status;
+
+  state_ = STATE_INITIALIZED;
+  db_.reset(db);
+
+  return STATUS_OK;
+}
+
+NotificationDatabase::Status NotificationDatabase::Destroy() {
+  DCHECK(sequence_checker_.CalledOnValidSequencedThread());
+
+  leveldb::Options options;
+  if (IsInMemoryDatabase()) {
+    if (!env_)
+      return STATUS_OK;  // The database has not been initialized.
+
+    options.env = env_.get();
+  }
+
+  state_ = STATE_DISABLED;
+  db_.reset();
+
+  return LevelDBStatusToStatus(
+      leveldb::DestroyDB(path_.AsUTF8Unsafe(), options));
+}
+
+}  // namespace content