[Sync] Remove DropAttachments from AttachmentService and SyncData

AttachmentService and SyncData no longer need to provide a drop method
beecause model type code can drop attachments using its AttachmentStore.

BUG=

Review URL: https://codereview.chromium.org/973513002

Cr-Commit-Position: refs/heads/master@{#318981}

3 files changed, 2 insertions, 17 deletions

diff --git a/sync/api/sync_data.cc b/sync/api/sync_data.cc
index 7fbdbc2..0dd567d 100644
--- a/sync/api/sync_data.cc
+++ b/sync/api/sync_data.cc
@@ -218,10 +218,4 @@ void SyncDataRemote::GetOrDownloadAttachments(
   attachment_service_.GetOrDownloadAttachments(attachment_ids, callback);
 }
 
-void SyncDataRemote::DropAttachments(
-    const AttachmentIdList& attachment_ids,
-    const AttachmentService::DropCallback& callback) {
-  attachment_service_.DropAttachments(attachment_ids, callback);
-}
-
 }  // namespace syncer
diff --git a/sync/api/sync_data.h b/sync/api/sync_data.h
index 4e5acd3..6815896 100644
--- a/sync/api/sync_data.h
+++ b/sync/api/sync_data.h
@@ -190,15 +190,6 @@ class SYNC_EXPORT SyncDataRemote : public SyncData {
   void GetOrDownloadAttachments(
       const AttachmentIdList& attachment_ids,
       const AttachmentService::GetOrDownloadCallback& callback);
-
-  // Drop (delete from local storage) the attachments associated with this
-  // SyncData specified in |attachment_ids|. This method will not delete
-  // attachments from the server.
-  //
-  // |callback| will be invoked when the operation is complete (successfully
-  // or otherwise).
-  void DropAttachments(const AttachmentIdList& attachment_ids,
-                       const AttachmentService::DropCallback& callback);
 };
 
 // gmock printer helper.
diff --git a/sync/api/sync_data_unittest.cc b/sync/api/sync_data_unittest.cc
index a0a83cd..94c3f4c 100644
--- a/sync/api/sync_data_unittest.cc
+++ b/sync/api/sync_data_unittest.cc
@@ -117,8 +117,8 @@ TEST_F(SyncDataTest, CreateRemoteData) {
   EXPECT_TRUE(data.GetAttachmentIds().empty());
 }
 
-// TODO(maniscalco): Add test cases that verify GetLocalAttachmentsForUpload and
-// DropAttachments calls are passed through to the underlying AttachmentService.
+// TODO(maniscalco): Add test cases that verify GetLocalAttachmentsForUpload
+// calls are passed through to the underlying AttachmentService.
 
 }  // namespace