Keep track of which attachments are referenced by which sync entries.

sync/syncable/mutable_entry.cc

 // Copyright 2012 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.
 
 #include "sync/syncable/mutable_entry.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "sync/internal_api/public/base/unique_position.h"
 #include "sync/syncable/directory.h"
 #include "sync/syncable/scoped_kernel_lock.h"
@@ skipping 215 matching lines @@
 }
 
 bool MutableEntry::PutPredecessor(const Id& predecessor_id) {
   MutableEntry predecessor(write_transaction(), GET_BY_ID, predecessor_id);
   if (!predecessor.good())
     return false;
   dir()->PutPredecessor(kernel_, predecessor.kernel_);
   return true;
 }
 
+void MutableEntry::PutAttachmentMetadata(
+    const sync_pb::AttachmentMetadata& attachment_metadata) {
+  DCHECK(kernel_);
+  write_transaction()->TrackChangesTo(kernel_);
+  if (kernel_->ref(ATTACHMENT_METADATA).SerializeAsString() !=
+      attachment_metadata.SerializeAsString()) {
+    dir()->UpdateAttachmentIndex(GetMetahandle(),
+                                 kernel_->ref(ATTACHMENT_METADATA),
+                                 attachment_metadata);
+    kernel_->put(ATTACHMENT_METADATA, attachment_metadata);
+    kernel_->mark_dirty(&dir()->kernel_->dirty_metahandles);
+  }
+}
+
 // This function sets only the flags needed to get this entry to sync.
 bool MarkForSyncing(MutableEntry* e) {
   DCHECK_NE(static_cast<MutableEntry*>(NULL), e);
   DCHECK(!e->IsRoot()) << "We shouldn't mark a permanent object for syncing.";
   if (!(e->PutIsUnsynced(true)))
     return false;
   e->PutSyncing(false);
   return true;
 }
 
 }  // namespace syncable
 }  // namespace syncer