Introduce the PlatformNotificationContext class.

content/browser/notifications/platform_notification_context.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/platform_notification_context.h"
+
+#include "base/threading/sequenced_worker_pool.h"
+#include "content/browser/notifications/notification_database.h"
+#include "content/browser/notifications/notification_database_data.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+
+// Name of the directory in the user's profile directory where the notification
+// database files should be stored.
+const base::FilePath::CharType kPlatformNotificationsDirectory[] =
+    FILE_PATH_LITERAL("Platform Notifications");
+
+PlatformNotificationContext::PlatformNotificationContext(
+    const base::FilePath& path)
+    : path_(path),
+      next_notification_id_(0) {
+}
+
+PlatformNotificationContext::~PlatformNotificationContext() {
+  // If the database has been initialized, it must be deleted on the task runner
+  // thread as closing it may cause file I/O.
+  if (database_) {
+    DCHECK(task_runner_);
+    task_runner_->DeleteSoon(FROM_HERE, database_.release());
+  }
+}
+
+void PlatformNotificationContext::ReadNotificationData(
+    int64_t notification_id,
+    const GURL& origin,
+    const ReadResultCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  LazyInitialize(
+       base::Bind(&PlatformNotificationContext::DoReadNotificationData,
+                  this, notification_id, origin, callback),
+       base::Bind(callback, false /* success */, NotificationDatabaseData()));
+}
+
+void PlatformNotificationContext::DoReadNotificationData(
+    int64_t notification_id,
+    const GURL& origin,
+    const ReadResultCallback& callback) {
+  NotificationDatabaseData database_data;
+  NotificationDatabase::Status status =
+      database_->ReadNotificationData(notification_id,
+                                      origin,
+                                      &database_data);
+
+  if (status == NotificationDatabase::STATUS_OK) {
+    BrowserThread::PostTask(BrowserThread::IO,
+                            FROM_HERE,
+                            base::Bind(callback,
+                                       true /* success */,
+                                       database_data));
+    return;
+  }
+
+  // TODO(peter): Record UMA on |status| for reading from the database.
+  // TODO(peter): Do the DeleteAndStartOver dance for STATUS_ERROR_CORRUPTED.
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(callback, false /* success */, NotificationDatabaseData()));
+}
+
+void PlatformNotificationContext::WriteNotificationData(
+    const GURL& origin,
+    const NotificationDatabaseData& database_data,
+    const WriteResultCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  LazyInitialize(
+       base::Bind(&PlatformNotificationContext::DoWriteNotificationData,
+                  this, origin, database_data, callback),
+       base::Bind(callback, false /* success */, 0 /* notification_id */));
+}
+
+void PlatformNotificationContext::DoWriteNotificationData(
+    const GURL& origin,
+    const NotificationDatabaseData& database_data,
+    const WriteResultCallback& callback) {
+  int64_t notification_id = next_notification_id_++;
+  NotificationDatabase::Status status =
+      database_->WriteNotificationData(notification_id,
+                                       origin,
+                                       database_data);
+
+  if (status == NotificationDatabase::STATUS_OK) {
+    BrowserThread::PostTask(BrowserThread::IO,
+                            FROM_HERE,
+                            base::Bind(callback,
+                                       true /* success */,
+                                       notification_id));
+    return;
+  }
+
+  // TODO(peter): Record UMA on |status| for reading from the database.
+  // TODO(peter): Do the DeleteAndStartOver dance for STATUS_ERROR_CORRUPTED.
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(callback, false /* success */, 0 /* notification_id */));
+}
+
+void PlatformNotificationContext::LazyInitialize(
+    const base::Closure& success_closure,
+    const base::Closure& failure_closure) {
+  if (!task_runner_) {
+    base::SequencedWorkerPool* pool = BrowserThread::GetBlockingPool();
+    base::SequencedWorkerPool::SequenceToken token = pool->GetSequenceToken();
+
+    task_runner_ = pool->GetSequencedTaskRunner(token);
+  }
+
+  if (!database_) {
+    database_.reset(new NotificationDatabase(GetDatabasePath()));

[Bernhard Bauer, 2015/03/13 17:24:01]

Hm, I think you might be able to simplify both this class and the database a
little bit if you construct the database on the database thread (in
OpenDatabase, lazily) and just directly jump to it here.

[Peter Beverloo, 2015/03/13 20:43:30]

Done.

+    task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&PlatformNotificationContext::OpenDatabase,
+                   this, success_closure, failure_closure));
+    return;
+  }
+
+  task_runner_->PostTask(FROM_HERE, success_closure);
+}
+
+void PlatformNotificationContext::OpenDatabase(
+    const base::Closure& success_closure,
+    const base::Closure& failure_closure) {
+  DCHECK(database_);
+
+  // TODO(peter): Record UMA on |status| for opening the database.
+  // TODO(peter): Do the DeleteAndStartOver dance for STATUS_ERROR_CORRUPTED.
+
+  NotificationDatabase::Status status =
+      database_->Open(true /* create_if_missing */);
+
+  if (status == NotificationDatabase::STATUS_OK) {
+    status = database_->GetNextNotificationId(&next_notification_id_);
+    if (status == NotificationDatabase::STATUS_OK) {
+      success_closure.Run();
+      return;
+    }
+  }
+
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE, failure_closure);
+}
+
+base::FilePath PlatformNotificationContext::GetDatabasePath() const {
+  if (path_.empty())
+    return path_;
+
+  return path_.Append(kPlatformNotificationsDirectory);
+}
+
+void PlatformNotificationContext::SetTaskRunnerForTesting(
+    const scoped_refptr<base::SequencedTaskRunner>& task_runner) {
+  task_runner_ = task_runner;
+}
+
+}  // namespace content