Add `chunk` segmented data library.

common/chunkstream/chunkNodePool.go

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package chunkstream
+
+import (
+        "sync"
+)
+
+var chunkNodePool = sync.Pool{
+        New: func() interface{} {
+                return &chunkNode{}
+        },
+}
+
+func newChunkNode(c Chunk) *chunkNode {
+        n := chunkNodePool.Get().(*chunkNode)
+        n.Chunk = c
+        return n
+}
+
+// chunkNode wraps a Chunk interface in a linked-list node.
+type chunkNode struct {
+        Chunk
+
+        next *chunkNode
+}
+
+func (n *chunkNode) release() {
+        n.Chunk.Release()
+        n.Chunk = nil
+        n.next = nil
+        chunkNodePool.Put(n)
+}