Add TimedTaskHelper to replace timer on SequencedTaskRunner

The code is based on the ObfuscatedFileUtil's ex-timer code
that replaces timer with PostDelayTask.

BUG=248826
R=tzik@chromium.org

Review URL: https://codereview.chromium.org/16775011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@205748 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 59 insertions, 0 deletions

diff --git a/webkit/browser/fileapi/timed_task_helper.h b/webkit/browser/fileapi/timed_task_helper.h
new file mode 100644
index 0000000..ad72fb8
--- /dev/null
+++ b/webkit/browser/fileapi/timed_task_helper.h
@@ -0,0 +1,59 @@
+// Copyright 2013 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.
+
+#ifndef WEBKIT_BROWSER_FILEAPI_TIMED_TASK_HELPER_H_
+#define WEBKIT_BROWSER_FILEAPI_TIMED_TASK_HELPER_H_
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/location.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/time.h"
+#include "webkit/storage/webkit_storage_export.h"
+
+namespace base {
+class SequencedTaskRunner;
+}
+
+namespace fileapi {
+
+// Works similarly as base::Timer, but takes SequencedTaskRunner and
+// runs tasks on it (instead of implicitly bound to a thread).
+// TODO(kinuko): This has nothing to do with fileapi. Move somewhere
+// more common place.
+class WEBKIT_STORAGE_EXPORT TimedTaskHelper {
+ public:
+  explicit TimedTaskHelper(base::SequencedTaskRunner* task_runner);
+  ~TimedTaskHelper();
+
+  bool IsRunning() const;
+  void Start(const tracked_objects::Location& posted_from,
+             base::TimeDelta delay,
+             const base::Closure& user_task);
+  void Reset();
+
+ private:
+  struct Tracker;
+  static void Fired(scoped_ptr<Tracker> tracker);
+
+  void OnFired(scoped_ptr<Tracker> tracker);
+  void PostDelayedTask(scoped_ptr<Tracker> tracker, base::TimeDelta delay);
+
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+  tracked_objects::Location posted_from_;
+  base::TimeDelta delay_;
+  base::Closure user_task_;
+
+  base::TimeTicks desired_run_time_;
+
+  // This is set to non-null and owned by a timer task while timer is running.
+  Tracker* tracker_;
+
+  DISALLOW_COPY_AND_ASSIGN(TimedTaskHelper);
+};
+
+}  // namespace fileapi
+
+#endif  // WEBKIT_BROWSER_FILEAPI_TIMED_TASK_HELPER_H_