Revert of [Sync] Add size and crc32c to AttachmentId.

sync/internal_api/public/base/attachment_id_proto.cc

Index: sync/internal_api/public/base/attachment_id_proto.cc
diff --git a/sync/internal_api/public/base/attachment_id_proto.cc b/sync/internal_api/public/base/attachment_id_proto.cc
index 6692ab70dc77d5bc0411a2222028b85e215ebcf2..52728cdf9f5b75dd974a485f22b4f0de99b0e56f 100644
--- a/sync/internal_api/public/base/attachment_id_proto.cc
+++ b/sync/internal_api/public/base/attachment_id_proto.cc
@@ -10,16 +10,13 @@
 
 namespace syncer {
 
-sync_pb::AttachmentIdProto CreateAttachmentIdProto(size_t size,
-                                                   uint32_t crc32c) {
+sync_pb::AttachmentIdProto CreateAttachmentIdProto() {
   sync_pb::AttachmentIdProto proto;
   std::string guid = base::StringToLowerASCII(base::GenerateGUID());
   DCHECK(!guid.empty());
   // Requirements are that this id must be a unique RFC4122 UUID, formatted in
   // lower case.
   proto.set_unique_id(guid);
-  proto.set_size_bytes(size);
-  proto.set_crc32c(crc32c);
   return proto;
 }