Convert //sync from scoped_ptr to std::unique_ptr

sync/test/fake_server/tombstone_entity.cc

Index: sync/test/fake_server/tombstone_entity.cc
diff --git a/sync/test/fake_server/tombstone_entity.cc b/sync/test/fake_server/tombstone_entity.cc
index 195c15a7201d1eb7c21881421c13df44aa5fe040..0b62bd89b96551694cbae999bd4e835a68fd79a1 100644
--- a/sync/test/fake_server/tombstone_entity.cc
+++ b/sync/test/fake_server/tombstone_entity.cc
@@ -19,10 +19,10 @@ namespace fake_server {
 TombstoneEntity::~TombstoneEntity() { }
 
 // static
-scoped_ptr<FakeServerEntity> TombstoneEntity::Create(const string& id) {
+std::unique_ptr<FakeServerEntity> TombstoneEntity::Create(const string& id) {
   const ModelType model_type = GetModelTypeFromId(id);
   CHECK_NE(model_type, syncer::UNSPECIFIED) << "Invalid ID was given: " << id;
-  return scoped_ptr<FakeServerEntity>(new TombstoneEntity(id, model_type));
+  return std::unique_ptr<FakeServerEntity>(new TombstoneEntity(id, model_type));
 }
 
 TombstoneEntity::TombstoneEntity(const string& id,