Help: Implement the initial version of the cross-platform help/about page.

chrome/browser/ui/webui/help/version_updater_chromeos.h

+// 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.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_HELP_VERSION_UPDATER_CHROMEOS_H_
+#define CHROME_BROWSER_UI_WEBUI_HELP_VERSION_UPDATER_CHROMEOS_H_
+#pragma once
+
+#include "base/compiler_specific.h"
+#include "chrome/browser/chromeos/dbus/update_engine_client.h"
+#include "chrome/browser/ui/webui/help/version_updater.h"
+
+class VersionUpdaterCros : public VersionUpdater,
+                           public chromeos::UpdateEngineClient::Observer {
+ public:
+  // VersionUpdater implementation.
+  virtual bool CanBeUpdated() const OVERRIDE;
+  virtual void CheckForUpdate(const StatusCallback& callback) OVERRIDE;
+  virtual void RelaunchBrowser() const OVERRIDE;
+
+ protected:
+  friend class VersionUpdater;
+
+  // Clients must use VersionUpdater::Create().
+  VersionUpdaterCros() {}
+  virtual ~VersionUpdaterCros();
+
+ private:
+  // UpdateEngineClient::Observer implementation.
+  virtual void UpdateStatusChanged(
+      const chromeos::UpdateEngineClient::Status& status) OVERRIDE;
+
+  // Callback used to communicate update status to the client.
+  StatusCallback callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(VersionUpdaterCros);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_HELP_VERSION_UPDATER_CHROMEOS_H_