Extract cgroups pkg.

Initial move before enhancing cgroups package.

Docker-DCO-1.1-Signed-off-by: Paul Nasrat <pnasrat@gmail.com> (github: pnasrat)

cgroups/cgroups_test.go

@@ -0,0 +1,27 @@
+package cgroups
+
+import (
+	"bytes"
+	"testing"
+)
+
+const (
+	cgroupsContents = `11:hugetlb:/
+10:perf_event:/
+9:blkio:/
+8:net_cls:/
+7:freezer:/
+6:devices:/
+5:memory:/
+4:cpuacct,cpu:/
+3:cpuset:/
+2:name=systemd:/user.slice/user-1000.slice/session-16.scope`
+)
+
+func TestParseCgroups(t *testing.T) {
+	r := bytes.NewBuffer([]byte(cgroupsContents))
+	_, err := parseCgroupFile("blkio", r)
+	if err != nil {
+		t.Fatal(err)
+	}
+}