Revert of Keep track of which attachments are referenced by which sync entries.

sync/syncable/directory_backing_store.cc

Index: sync/syncable/directory_backing_store.cc
diff --git a/sync/syncable/directory_backing_store.cc b/sync/syncable/directory_backing_store.cc
index ec28a53d661a47fcc9baaa99774301c01d953701..e466548b172ee9c039af93aa1d51f837bb63a017 100644
--- a/sync/syncable/directory_backing_store.cc
+++ b/sync/syncable/directory_backing_store.cc
@@ -70,11 +70,6 @@
     entry.ref(static_cast<UniquePositionField>(i)).SerializeToString(&temp);
     statement->BindBlob(index++, temp.data(), temp.length());
   }
-  for (; i < ATTACHMENT_METADATA_FIELDS_END; ++i) {
-    std::string temp;
-    entry.ref(static_cast<AttachmentMetadataField>(i)).SerializeToString(&temp);
-    statement->BindBlob(index++, temp.data(), temp.length());
-  }
 }
 
 // The caller owns the returned EntryKernel*.  Assumes the statement currently
@@ -118,10 +113,6 @@
 
     kernel->mutable_ref(static_cast<UniquePositionField>(i)) =
         UniquePosition::FromProto(proto);
-  }
-  for (; i < ATTACHMENT_METADATA_FIELDS_END; ++i) {
-    kernel->mutable_ref(static_cast<AttachmentMetadataField>(i)).ParseFromArray(
-        statement->ColumnBlob(i), statement->ColumnByteLength(i));
   }
   return kernel.Pass();
 }