[Chromoting] Add DataChannelManager to manage optional incoming data channels

remoting/proto/test.proto

Index: remoting/proto/test.proto
diff --git a/remoting/proto/test.proto b/remoting/proto/test.proto
new file mode 100644
index 0000000000000000000000000000000000000000..c02f408d6d4271f13f927c78611c3fe324a802e3
--- /dev/null
+++ b/remoting/proto/test.proto
@@ -0,0 +1,17 @@
+// Copyright 2017 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.
+
+// Protocol for test only.
+
+syntax = "proto2";
+
+option optimize_for = LITE_RUNTIME;
+
+package remoting.protocol;
+
+// The proto for DataChannelManager test cases.
+// Next Id: 2
+message DataChannelManagerTestProto {
+  optional int32 data = 1;
+}