Remove utils::MakeTempDirectory().

In favor of base::ScopedTempDir, except for PostinstallRunnerAction,
where the temp directory needs to be removed for every partition.

ScopedDirRemover is also removed because it's no longer used.

Test: ./update_engine_unittests
Test: cros_workon_make update_engine --test
Bug: 26955860

Change-Id: I954e6e892aff0cf9f8434a77408dc3c9eb64c1b5
diff --git a/payload_consumer/postinstall_runner_action.cc b/payload_consumer/postinstall_runner_action.cc
index fa89857..c24590e 100644
--- a/payload_consumer/postinstall_runner_action.cc
+++ b/payload_consumer/postinstall_runner_action.cc
@@ -113,8 +113,9 @@
 #ifdef __ANDROID__
   fs_mount_dir_ = "/postinstall";
 #else   // __ANDROID__
-  TEST_AND_RETURN(
-      utils::MakeTempDirectory("au_postint_mount.XXXXXX", &fs_mount_dir_));
+  base::FilePath temp_dir;
+  TEST_AND_RETURN(base::CreateNewTempDirectory("au_postint_mount", &temp_dir));
+  fs_mount_dir_ = temp_dir.value();
 #endif  // __ANDROID__
 
   base::FilePath postinstall_path(partition.postinstall_path);