Keep browser process alive while there are platform apps with background pages running.

chrome/browser/extensions/platform_app_service.h

Index: chrome/browser/extensions/platform_app_service.h
diff --git a/chrome/browser/extensions/platform_app_service.h b/chrome/browser/extensions/platform_app_service.h
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+// 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_EXTENSIONS_PLATFORM_APP_SERVICE_H_
+#define CHROME_BROWSER_EXTENSIONS_PLATFORM_APP_SERVICE_H_
+
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/profiles/profile_keyed_service.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+
+namespace extensions {
+
+// The PlatformAppService provides services for platform apps, such as
+// keeping the browser process alive while they are running.
+// TODO(benwells): Merge functionality of ShellWindowRegistry into this class.
+class PlatformAppService : public ProfileKeyedService,
+                           public content::NotificationObserver {
+ public:
+  explicit PlatformAppService(Profile* profile);
+  virtual ~PlatformAppService();
+
+ private:
+  // content::NotificationObserver:
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  content::NotificationRegistrar registrar_;
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_PLATFORM_APP_SERVICE_H_