[Sync] Add support for loading, updating and querying delete journals in

sync/syncable/on_disk_directory_backing_store.h

Index: sync/syncable/on_disk_directory_backing_store.h
diff --git a/sync/syncable/on_disk_directory_backing_store.h b/sync/syncable/on_disk_directory_backing_store.h
index 0bf720bf540a2eb85d05189734c74d828ff457f9..62492b0a384ad405ef5ae6922bab390a5e2e5493 100644
--- a/sync/syncable/on_disk_directory_backing_store.h
+++ b/sync/syncable/on_disk_directory_backing_store.h
@@ -20,12 +20,14 @@ class OnDiskDirectoryBackingStore : public DirectoryBackingStore {
   virtual ~OnDiskDirectoryBackingStore();
   virtual DirOpenResult Load(
       MetahandlesIndex* entry_bucket,
+      IdsIndex* delete_journals,
       Directory::KernelLoadInfo* kernel_load_info) OVERRIDE;
 
   // A helper function that will make one attempt to load the directory.
   // Unlike Load(), it does not attempt to recover from failure.
   DirOpenResult TryLoad(
       MetahandlesIndex* entry_bucket,
+      IdsIndex* delete_journals,
       Directory::KernelLoadInfo* kernel_load_info);
 
  protected: