Convert //sync from scoped_ptr to std::unique_ptr

sync/engine/directory_update_handler.h

Index: sync/engine/directory_update_handler.h
diff --git a/sync/engine/directory_update_handler.h b/sync/engine/directory_update_handler.h
index 85601e9b12bd9b3fa08e608863d7bdda5d745338..219e58480882a9c868d37bb87b871f82025ff2f1 100644
--- a/sync/engine/directory_update_handler.h
+++ b/sync/engine/directory_update_handler.h
@@ -6,10 +6,10 @@
 #define SYNC_ENGINE_DIRECTORY_UPDATE_HANDLER_H_
 
 #include <map>
+#include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
 #include "sync/base/sync_export.h"
 #include "sync/engine/process_updates_util.h"
 #include "sync/engine/update_handler.h"
@@ -104,7 +104,7 @@ class SYNC_EXPORT DirectoryUpdateHandler : public UpdateHandler {
   scoped_refptr<ModelSafeWorker> worker_;
   DirectoryTypeDebugInfoEmitter* debug_info_emitter_;
 
-  scoped_ptr<sync_pb::GarbageCollectionDirective> cached_gc_directive_;
+  std::unique_ptr<sync_pb::GarbageCollectionDirective> cached_gc_directive_;
 
   DISALLOW_COPY_AND_ASSIGN(DirectoryUpdateHandler);
 };