Move non-API code out of sync/api/attachments/

sync/api/attachments/attachment_downloader.h

-// Copyright 2014 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 SYNC_API_ATTACHMENTS_ATTACHMENT_DOWNLOADER_H_
-#define SYNC_API_ATTACHMENTS_ATTACHMENT_DOWNLOADER_H_
-
-#include "base/callback.h"
-#include "base/memory/scoped_ptr.h"
-#include "google_apis/gaia/oauth2_token_service_request.h"
-#include "sync/api/attachments/attachment.h"
-#include "sync/base/sync_export.h"
-
-namespace net {
-class URLRequestContextGetter;
-}  // namespace net
-
-namespace syncer {
-
-// AttachmentDownloader is responsible for downloading attachments from server.
-class SYNC_EXPORT AttachmentDownloader {
- public:
-  // The result of a DownloadAttachment operation.
-  enum DownloadResult {
-    DOWNLOAD_SUCCESS,            // No error, attachment was downloaded
-                                 // successfully.
-    DOWNLOAD_UNSPECIFIED_ERROR,  // An unspecified error occurred.
-  };
-
-  typedef base::Callback<void(const DownloadResult&, scoped_ptr<Attachment>)>
-      DownloadCallback;
-
-  virtual ~AttachmentDownloader();
-
-  // Download attachment referred by |attachment_id| and invoke |callback| when
-  // done.
-  //
-  // |callback| will receive a DownloadResult code and an Attachment object. If
-  // DownloadResult is not DOWNLOAD_SUCCESS then attachment pointer is NULL.
-  virtual void DownloadAttachment(const AttachmentId& attachment_id,
-                                  const DownloadCallback& callback) = 0;
-
-  // Create instance of AttachmentDownloaderImpl.
-  // |sync_service_url| is the URL of the sync service.
-  //
-  // |url_request_context_getter| provides a URLRequestContext.
-  //
-  // |account_id| is the account id to use for downloads.
-  //
-  // |scopes| is the set of scopes to use for downloads.
-  //
-  // |token_service_provider| provides an OAuth2 token service.
-  static scoped_ptr<AttachmentDownloader> Create(
-      const GURL& sync_service_url,
-      const scoped_refptr<net::URLRequestContextGetter>&
-          url_request_context_getter,
-      const std::string& account_id,
-      const OAuth2TokenService::ScopeSet scopes,
-      scoped_ptr<OAuth2TokenServiceRequest::TokenServiceProvider>
-          token_service_provider);
-};
-
-}  // namespace syncer
-
-#endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_DOWNLOADER_H_