[Sync] Move attachments code out of core/.

components/sync/api/attachments/attachment_service.h

Index: components/sync/api/attachments/attachment_service.h
diff --git a/components/sync/core/attachments/attachment_service.h b/components/sync/api/attachments/attachment_service.h
similarity index 74%
rename from components/sync/core/attachments/attachment_service.h
rename to components/sync/api/attachments/attachment_service.h
index b59037293dcd382f2f9cd940a85df39bd42edd81..ad1c029d0f9bd8f330f005b369729480e6e3ce0c 100644
--- a/components/sync/core/attachments/attachment_service.h
+++ b/components/sync/api/attachments/attachment_service.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef COMPONENTS_SYNC_CORE_ATTACHMENTS_ATTACHMENT_SERVICE_H_
-#define COMPONENTS_SYNC_CORE_ATTACHMENTS_ATTACHMENT_SERVICE_H_
+#ifndef COMPONENTS_SYNC_API_ATTACHMENTS_ATTACHMENT_SERVICE_H_
+#define COMPONENTS_SYNC_API_ATTACHMENTS_ATTACHMENT_SERVICE_H_
 
 #include <memory>
 
@@ -13,7 +13,10 @@
 
 namespace syncer {
 
+class AttachmentDownloader;
 class AttachmentStore;
+class AttachmentStoreForSync;
+class AttachmentUploader;
 class SyncData;
 
 // AttachmentService is responsible for managing a model type's attachments.
@@ -48,7 +51,18 @@ class AttachmentService {
     virtual void OnAttachmentUploaded(const AttachmentId& attachment_id) = 0;
   };
 
-  AttachmentService();
+  // Create a concrete AttachmentService.
+  static std::unique_ptr<AttachmentService> Create(
+      std::unique_ptr<AttachmentStoreForSync> attachment_store,
+      std::unique_ptr<AttachmentUploader> attachment_uploader,
+      std::unique_ptr<AttachmentDownloader> attachment_downloader,
+      Delegate* delegate,
+      const base::TimeDelta& initial_backoff_delay,
+      const base::TimeDelta& max_backoff_delay);
+
+  // Create an AttachmentService suitable for use in tests.
+  static std::unique_ptr<AttachmentService> CreateForTest();
+
   virtual ~AttachmentService();
 
   // See SyncData::GetOrDownloadAttachments.
@@ -72,4 +86,4 @@ class AttachmentService {
 
 }  // namespace syncer
 
-#endif  // COMPONENTS_SYNC_CORE_ATTACHMENTS_ATTACHMENT_SERVICE_H_
+#endif  // COMPONENTS_SYNC_API_ATTACHMENTS_ATTACHMENT_SERVICE_H_