[Sync] Add size and crc32c to AttachmentId.

sync/api/attachments/attachment_id.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SYNC_API_ATTACHMENTS_ATTACHMENT_ID_H_
 #define SYNC_API_ATTACHMENTS_ATTACHMENT_ID_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 17 matching lines @@
 
   // Default copy and assignment are welcome.
 
   bool operator==(const AttachmentId& other) const;
 
   bool operator!=(const AttachmentId& other) const;
 
   // Needed for using AttachmentId as key in std::map.
   bool operator<(const AttachmentId& other) const;
 
-  // Creates a unique attachment id.
-  static AttachmentId Create();
+  // Creates a unique id for an attachment.
+  //
+  // |size| is the attachment's size in bytes.
+  //
+  // |crc32c| is the attachment's crc32c.
+  static AttachmentId Create(size_t size, uint32_t crc32c);
 
   // Creates an attachment id from an initialized proto.
   static AttachmentId CreateFromProto(const sync_pb::AttachmentIdProto& proto);
 
   const sync_pb::AttachmentIdProto& GetProto() const;
 
+  // Returns the size (in bytes) the attachment.
+  size_t GetSize() const;
+
+  // Returns the crc32c the attachment.
+  uint32_t GetCrc32c() const;
+
  private:
   // Necessary since we forward-declare sync_pb::AttachmentIdProto; see comments
   // in immutable.h.
   struct SYNC_EXPORT ImmutableAttachmentIdProtoTraits {
     typedef sync_pb::AttachmentIdProto* Wrapper;
     static void InitializeWrapper(Wrapper* wrapper);
     static void DestroyWrapper(Wrapper* wrapper);
     static const sync_pb::AttachmentIdProto& Unwrap(const Wrapper& wrapper);
     static sync_pb::AttachmentIdProto* UnwrapMutable(Wrapper* wrapper);
     static void Swap(sync_pb::AttachmentIdProto* t1,
                      sync_pb::AttachmentIdProto* t2);
   };
 
   typedef Immutable<sync_pb::AttachmentIdProto,
                     ImmutableAttachmentIdProtoTraits>
       ImmutableAttachmentIdProto;
 
   ImmutableAttachmentIdProto proto_;
 
   AttachmentId(sync_pb::AttachmentIdProto* proto);
 };
 
 typedef std::vector<AttachmentId> AttachmentIdList;
 typedef std::set<AttachmentId> AttachmentIdSet;
 
 }  // namespace syncer
 
 #endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_ID_H_