[Sync] Move //sync to //components/sync.

sync/internal_api/public/attachments/attachment_service_proxy.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_INTERNAL_API_PUBLIC_ATTACHMENTS_ATTACHMENT_SERVICE_PROXY_H_
-#define SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_ATTACHMENT_SERVICE_PROXY_H_
-
-#include "base/callback.h"
-#include "base/macros.h"
-#include "base/memory/weak_ptr.h"
-#include "base/sequenced_task_runner.h"
-#include "base/task_runner.h"
-#include "sync/api/attachments/attachment.h"
-#include "sync/base/sync_export.h"
-#include "sync/internal_api/public/attachments/attachment_service.h"
-
-namespace syncer {
-
-// AttachmentServiceProxy wraps an AttachmentService allowing multiple threads
-// to share the wrapped AttachmentService and invoke its methods in the
-// appropriate thread.
-//
-// Callbacks passed to methods on this class will be invoked in the same thread
-// from which the method was called.
-//
-// This class does not own its wrapped AttachmentService object.  This class
-// holds a WeakPtr to the wrapped object.  Once the the wrapped object is
-// destroyed, method calls on this object will be no-ops.
-//
-// Users of this class should take care to destroy the wrapped object on the
-// correct thread (wrapped_task_runner).
-//
-// This class is thread-safe and is designed to be passed by const-ref.
-class SYNC_EXPORT AttachmentServiceProxy : public AttachmentService {
- public:
-  // Default copy and assignment are welcome.
-
-  // Construct an invalid AttachmentServiceProxy.
-  AttachmentServiceProxy();
-
-  // Construct an AttachmentServiceProxy that forwards calls to |wrapped| on the
-  // |wrapped_task_runner| thread.
-  //
-  // Note, this object does not own |wrapped|.  When |wrapped| is destroyed,
-  // calls to this object become no-ops.
-  AttachmentServiceProxy(
-      const scoped_refptr<base::SequencedTaskRunner>& wrapped_task_runner,
-      const base::WeakPtr<syncer::AttachmentService>& wrapped);
-
-  AttachmentServiceProxy(const AttachmentServiceProxy& other);
-
-  ~AttachmentServiceProxy() override;
-
-  void GetOrDownloadAttachments(const AttachmentIdList& attachment_ids,
-                                const GetOrDownloadCallback& callback) override;
-  void UploadAttachments(const AttachmentIdList& attachment_ids) override;
-
- protected:
-  // Core does the work of proxying calls to AttachmentService methods from one
-  // thread to another so AttachmentServiceProxy can be an easy-to-use,
-  // non-ref-counted A ref-counted class.
-  //
-  // Callback from AttachmentService are proxied back using free functions
-  // defined in the .cc file (ProxyFooCallback functions).
-  //
-  // Core is ref-counted because we want to allow AttachmentServiceProxy to be
-  // copy-constructable while allowing for different implementations of Core
-  // (e.g. one type of core might own the wrapped AttachmentService).
-  //
-  // Calls to objects of this class become no-ops once its wrapped object is
-  // destroyed.
-  class SYNC_EXPORT Core : public AttachmentService,
-                           public base::RefCountedThreadSafe<Core> {
-   public:
-    // Construct an AttachmentServiceProxyCore that forwards calls to |wrapped|.
-    explicit Core(const base::WeakPtr<syncer::AttachmentService>& wrapped);
-
-    // AttachmentService implementation.
-    void GetOrDownloadAttachments(
-        const AttachmentIdList& attachment_ids,
-        const GetOrDownloadCallback& callback) override;
-    void UploadAttachments(const AttachmentIdList& attachment_ids) override;
-
-   protected:
-    ~Core() override;
-
-   private:
-    friend class base::RefCountedThreadSafe<Core>;
-
-    base::WeakPtr<AttachmentService> wrapped_;
-
-    DISALLOW_COPY_AND_ASSIGN(Core);
-  };
-
-  // Used in tests to create an AttachmentServiceProxy with a custom Core.
-  AttachmentServiceProxy(
-      const scoped_refptr<base::SequencedTaskRunner>& wrapped_task_runner,
-      const scoped_refptr<Core>& core);
-
- private:
-  scoped_refptr<base::SequencedTaskRunner> wrapped_task_runner_;
-  scoped_refptr<Core> core_;
-};
-
-}  // namespace syncer
-
-#endif  // SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_ATTACHMENT_SERVICE_PROXY_H_