Move (most of) chrome/browser/drive into components/drive/service.

chrome/browser/drive/drive_notification_observer.h

-// Copyright (c) 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 CHROME_BROWSER_DRIVE_DRIVE_NOTIFICATION_OBSERVER_H_
-#define CHROME_BROWSER_DRIVE_DRIVE_NOTIFICATION_OBSERVER_H_
-
-namespace drive {
-
-// Interface for classes which need to know when to check Google Drive for
-// updates.
-class DriveNotificationObserver {
- public:
-  // Called when a notification from Google Drive is received.
-  virtual void OnNotificationReceived() = 0;
-
-  // Called when XMPP-based push notification is enabled or disabled.
-  virtual void OnPushNotificationEnabled(bool enabled) {}
-
- protected:
-  virtual ~DriveNotificationObserver() {}
-};
-
-}  // namespace drive
-
-#endif  // CHROME_BROWSER_DRIVE_DRIVE_NOTIFICATION_OBSERVER_H_