Add `chunk` segmented data library.

common/chunkstream/chunk.go

Index: common/chunkstream/chunk.go
diff --git a/common/chunkstream/chunk.go b/common/chunkstream/chunk.go
new file mode 100644
index 0000000000000000000000000000000000000000..57c973ffad4539dfad6a2544e0dbbd5791dc742a
--- /dev/null
+++ b/common/chunkstream/chunk.go
@@ -0,0 +1,21 @@
+// 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
+
+// Chunk wraps a fixed-size byte buffer. It is the primary interface used by
+// the chunk library.
+//
+// A Chunk reference should be released once the user is finished with it. After
+// being released, it may no longer be accessed.
+type Chunk interface {

[iannucci, 2015/11/05 01:10:08]

Is this intended to be used outside of the package? Is there a reason not to
have it be a *struct?

May be worth specifying that Bytes and Len must always return the SAME data.

[dnj, 2015/11/13 23:22:03]

I'm going to kill Len().

+	// Bytes returns the underlying byte slice contained by this Chunk.
+	Bytes() []byte
+	// Len returns the length of the underlying byte slice.
+	Len() int

[iannucci, 2015/11/05 01:10:07]

maybe no Len() and then put Len() on chunkNode

[dnj, 2015/11/13 23:22:03]

Done.

+
+	// Release releases the Chunk. After being released, a Chunk's methods may no
+	// longer be used.
+	Release()
+}