[Sync] Remove DropAttachments from AttachmentService and SyncData

sync/internal_api/public/attachments/attachment_service.h

Index: sync/internal_api/public/attachments/attachment_service.h
diff --git a/sync/internal_api/public/attachments/attachment_service.h b/sync/internal_api/public/attachments/attachment_service.h
index 758f960a659b92a6c33fd7518ef6d98b68e7de9b..944a71f48f4f5304b670feeedb525e5c21e81991 100644
--- a/sync/internal_api/public/attachments/attachment_service.h
+++ b/sync/internal_api/public/attachments/attachment_service.h
@@ -36,15 +36,6 @@ class SYNC_EXPORT AttachmentService {
       void(const GetOrDownloadResult&, scoped_ptr<AttachmentMap> attachments)>
       GetOrDownloadCallback;
 
-  // The result of a DropAttachments operation.
-  enum DropResult {
-    DROP_SUCCESS,            // No error, all attachments dropped.
-    DROP_UNSPECIFIED_ERROR,  // An unspecified error occurred. Some or all
-                             // attachments may not have been dropped.
-  };
-
-  typedef base::Callback<void(const DropResult&)> DropCallback;
-
   // An interface that embedder code implements to be notified about different
   // events that originate from AttachmentService.
   // This interface will be called from the same thread AttachmentService was
@@ -71,10 +62,6 @@ class SYNC_EXPORT AttachmentService {
       const AttachmentIdList& attachment_ids,
       const GetOrDownloadCallback& callback) = 0;
 
-  // See SyncData::DropAttachments.
-  virtual void DropAttachments(const AttachmentIdList& attachment_ids,
-                               const DropCallback& callback) = 0;
-
   // Schedules the attachments identified by |attachment_ids| to be uploaded to
   // the server.
   //