[Sync] Add size and crc32c to AttachmentId.

sync/api/attachments/attachment.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_H_
 #define SYNC_API_ATTACHMENTS_ATTACHMENT_H_
 
 #include <map>
 #include <vector>
 
@@ skipping 16 matching lines @@
  public:
   ~Attachment();
 
   // Default copy and assignment are welcome.
 
   // Creates an attachment with a unique id and the supplied data.
   //
   // Used when creating a brand new attachment.
   static Attachment Create(const scoped_refptr<base::RefCountedMemory>& data);
 
-  // Creates an attachment with the supplied id, data and crc32c.
+  // Creates an attachment with the supplied id and data.
   //
   // Used when you want to recreate a specific attachment. E.g. creating a local
   // copy of an attachment that already exists on the sync server.
   static Attachment CreateFromParts(
       const AttachmentId& id,
-      const scoped_refptr<base::RefCountedMemory>& data,
-      uint32_t crc32c);
+      const scoped_refptr<base::RefCountedMemory>& data);
 
   // Returns this attachment's id.
   const AttachmentId& GetId() const;
 
   // Returns this attachment's data.
   const scoped_refptr<base::RefCountedMemory>& GetData() const;
 
   // Returns precomputed crc32c hash of data. In ideal case this hash is
   // computed when attachment is first created. It is then passed around through
   // local attachment store and attachment server. Crc is verified when
   // attachment is downloaded from server or loaded from local storage.
   uint32_t GetCrc32c() const;
 
  private:
   AttachmentId id_;
   scoped_refptr<base::RefCountedMemory> data_;
-  uint32_t crc32c_;
 
   Attachment(const AttachmentId& id,
-             const scoped_refptr<base::RefCountedMemory>& data,
-             uint32_t crc32c);
+             const scoped_refptr<base::RefCountedMemory>& data);
 };
 
 typedef std::vector<syncer::Attachment> AttachmentList;
 typedef std::map<AttachmentId, Attachment> AttachmentMap;
 
 }  // namespace syncer
 
 #endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_H_