Remove balloon notification code. The last user was the Linux GTK port but that's deleted now.

chrome/browser/notifications/notification_prefs_manager.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_NOTIFICATIONS_NOTIFICATION_PREFS_MANAGER_H_
-#define CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_PREFS_MANAGER_H_
-
-#include "chrome/browser/notifications/balloon_collection.h"
-
-class PrefService;
-class PrefRegistrySimple;
-
-// This interface is used to access and mutate the preferences related to
-// desktop notifications.
-class NotificationPrefsManager {
- public:
-  explicit NotificationPrefsManager(PrefService* prefs);
-  virtual ~NotificationPrefsManager() {}
-
-  // Registers preferences.
-  static void RegisterPrefs(PrefRegistrySimple* registry);
-
-  // Gets the preference indicating where notifications should be placed.
-  virtual BalloonCollection::PositionPreference
-      GetPositionPreference() const = 0;
-
-  // Sets the preference that indicates where notifications should
-  // be placed on the screen.
-  virtual void SetPositionPreference(
-      BalloonCollection::PositionPreference preference) = 0;
-
- protected:
-  NotificationPrefsManager() {}
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(NotificationPrefsManager);
-};
-
-#endif  // CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_PREFS_MANAGER_H_