Store attachment crc in AttachmentStore

sync/internal_api/attachments/fake_attachment_downloader.cc

Index: sync/internal_api/attachments/fake_attachment_downloader.cc
diff --git a/sync/internal_api/attachments/fake_attachment_downloader.cc b/sync/internal_api/attachments/fake_attachment_downloader.cc
index 1f2795e7dfdd849c42e122f13de4c907068555a3..92124d045d76c6cc1d2fc30d8ac6804554885c2e 100644
--- a/sync/internal_api/attachments/fake_attachment_downloader.cc
+++ b/sync/internal_api/attachments/fake_attachment_downloader.cc
@@ -6,6 +6,7 @@
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
+#include "sync/internal_api/public/attachments/attachment_util.h"
 
 namespace syncer {
 
@@ -24,8 +25,9 @@ void FakeAttachmentDownloader::DownloadAttachment(
   // attachment.
   scoped_refptr<base::RefCountedMemory> data(new base::RefCountedBytes());
   scoped_ptr<Attachment> attachment;
+  uint32_t crc = ComputeCrc32c(data);
   attachment.reset(
-      new Attachment(Attachment::CreateWithId(attachment_id, data)));
+      new Attachment(Attachment::RestoreExisting(attachment_id, data, crc)));
   base::MessageLoop::current()->PostTask(
       FROM_HERE,
       base::Bind(callback, DOWNLOAD_SUCCESS, base::Passed(&attachment)));