libcontainer: migrate from base::MakeUnique to std::make_unique

base::MakeUnique is being deprecated as we can now use std::make_unique
when compiling code in the C++14 mode.

BUG=chromium:769107
CQ-DEPEND=CL:669672
TEST=Run unit tests.

Change-Id: Id567982674091fb924cdb2d9408f08c0d23e3c9a
Reviewed-on: https://chromium-review.googlesource.com/693744
Commit-Ready: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/libcontainer/libcontainer_unittest.cc b/libcontainer/libcontainer_unittest.cc
index c315d76..4bea7f0 100644
--- a/libcontainer/libcontainer_unittest.cc
+++ b/libcontainer/libcontainer_unittest.cc
@@ -16,7 +16,6 @@
 #include <base/files/file_path.h>
 #include <base/files/file_util.h>
 #include <base/files/scoped_temp_dir.h>
-#include <base/memory/ptr_util.h>
 #include <gtest/gtest.h>
 
 #include "libcontainer/cgroup.h"
@@ -93,7 +92,7 @@
       const base::FilePath& cgroup_parent,
       uid_t cgroup_owner,
       gid_t cgroup_group) {
-    return base::MakeUnique<MockCgroup>(g_mock_cgroup_state);
+    return std::make_unique<MockCgroup>(g_mock_cgroup_state);
   }
 
   int Freeze() override { return state_->freeze_ret; }