Store attachment crc in AttachmentStore

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 14 matching lines @@
 // It is cheap to copy Attachments. Feel free to store and return by value.
 class SYNC_EXPORT Attachment {
  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);
+  static Attachment CreateNew(
+      const scoped_refptr<base::RefCountedMemory>& data);
 
   // 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 CreateWithId(
+  static Attachment RestoreExisting(

[pavely, 2014/11/10 23:45:29]

I wanted to generalize name since it is not create with id and crc (essentially
all attachment metadata). One option was Create/CreateWithMetadata, but word
"metadata" is overloaded. I think CreateNew/RestoreExisting reflect intention.

[maniscalco, 2014/11/11 00:44:53]

I see.  WDYT about CreateFromParts?  Restore in the name seems a little odd to
me, but I have a hard time explaining why exactly.

[pavely, 2014/11/11 22:27:14]

The reason is Restore means something is broken, deteriorated and now we are
restoring it to glory.
I'm Ok with CreateFromParts.

       const AttachmentId& id,
-      const scoped_refptr<base::RefCountedMemory>& data);
+      const scoped_refptr<base::RefCountedMemory>& data,
+      uint32_t crc32c);
 
   // Returns this attachment's id.
   const AttachmentId& GetId() const;
 
   // Returns this attachment's data.
   const scoped_refptr<base::RefCountedMemory>& GetData() const;
 
+  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);
+             const scoped_refptr<base::RefCountedMemory>& data,
+             uint32_t crc32c);
 };
 
 typedef std::vector<syncer::Attachment> AttachmentList;
 typedef std::map<AttachmentId, Attachment> AttachmentMap;
 
 }  // namespace syncer
 
 #endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_H_