[Sync] Refactor AttachmentStore classes. Introduce concept of referrer.

sync/internal_api/attachments/attachment_store_handle.cc

Index: sync/internal_api/attachments/attachment_store_handle.cc
diff --git a/sync/internal_api/attachments/attachment_store_handle.cc b/sync/internal_api/attachments/attachment_store_handle.cc
deleted file mode 100644
index 5e3591b7e4dfaf7c7a730008b827e0f4b13cd876..0000000000000000000000000000000000000000
--- a/sync/internal_api/attachments/attachment_store_handle.cc
+++ /dev/null
@@ -1,88 +0,0 @@
-// 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.
-
-#include "sync/internal_api/public/attachments/attachment_store_handle.h"
-
-#include "base/bind.h"
-#include "base/location.h"
-#include "base/sequenced_task_runner.h"
-#include "sync/api/attachments/attachment.h"
-
-namespace syncer {
-
-namespace {
-
-// NoOp is needed to bind base::Passed(backend) in AttachmentStoreHandle dtor.
-// It doesn't need to do anything.
-void NoOp(scoped_ptr<AttachmentStoreBackend> backend) {
-}
-
-}  // namespace
-
-AttachmentStoreHandle::AttachmentStoreHandle(
-    scoped_ptr<AttachmentStoreBackend> backend,
-    const scoped_refptr<base::SequencedTaskRunner>& backend_task_runner)
-    : backend_(backend.Pass()), backend_task_runner_(backend_task_runner) {
-  DCHECK(backend_);
-  DCHECK(backend_task_runner_.get());
-}
-
-AttachmentStoreHandle::~AttachmentStoreHandle() {
-  DCHECK(backend_);
-  // To delete backend post task that doesn't do anything, but binds backend
-  // through base::Passed. This way backend will be deleted regardless whether
-  // task runs or not.
-  backend_task_runner_->PostTask(
-      FROM_HERE, base::Bind(&NoOp, base::Passed(&backend_)));
-}
-
-void AttachmentStoreHandle::Init(const InitCallback& callback) {
-  DCHECK(CalledOnValidThread());
-  backend_task_runner_->PostTask(
-      FROM_HERE, base::Bind(&AttachmentStoreBackend::Init,
-                            base::Unretained(backend_.get()), callback));
-}
-
-void AttachmentStoreHandle::Read(const AttachmentIdList& ids,
-                                 const ReadCallback& callback) {
-  DCHECK(CalledOnValidThread());
-  backend_task_runner_->PostTask(
-      FROM_HERE, base::Bind(&AttachmentStoreBackend::Read,
-                            base::Unretained(backend_.get()), ids, callback));
-}
-
-void AttachmentStoreHandle::Write(const AttachmentList& attachments,
-                                  const WriteCallback& callback) {
-  DCHECK(CalledOnValidThread());
-  backend_task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(&AttachmentStoreBackend::Write,
-                 base::Unretained(backend_.get()), attachments, callback));
-}
-
-void AttachmentStoreHandle::Drop(const AttachmentIdList& ids,
-                                 const DropCallback& callback) {
-  DCHECK(CalledOnValidThread());
-  backend_task_runner_->PostTask(
-      FROM_HERE, base::Bind(&AttachmentStoreBackend::Drop,
-                            base::Unretained(backend_.get()), ids, callback));
-}
-
-void AttachmentStoreHandle::ReadMetadata(const AttachmentIdList& ids,
-                                         const ReadMetadataCallback& callback) {
-  DCHECK(CalledOnValidThread());
-  backend_task_runner_->PostTask(
-      FROM_HERE, base::Bind(&AttachmentStoreBackend::ReadMetadata,
-                            base::Unretained(backend_.get()), ids, callback));
-}
-
-void AttachmentStoreHandle::ReadAllMetadata(
-    const ReadMetadataCallback& callback) {
-  DCHECK(CalledOnValidThread());
-  backend_task_runner_->PostTask(
-      FROM_HERE, base::Bind(&AttachmentStoreBackend::ReadAllMetadata,
-                            base::Unretained(backend_.get()), callback));
-}
-
-}  // namespace syncer