Adds Mojo IDL.

third_party/WebKit/Source/core/mojo/MojoReadMessageResult.idl

Index: third_party/WebKit/Source/core/mojo/MojoReadMessageResult.idl
diff --git a/third_party/WebKit/Source/core/mojo/MojoReadMessageResult.idl b/third_party/WebKit/Source/core/mojo/MojoReadMessageResult.idl
new file mode 100644
index 0000000000000000000000000000000000000000..dcfb419815038b0e0bca73da11bc5dbe6f7db19e
--- /dev/null
+++ b/third_party/WebKit/Source/core/mojo/MojoReadMessageResult.idl
@@ -0,0 +1,10 @@
+// Copyright 2016 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.
+
+dictionary MojoReadMessageResult {
+  // TODO(alokp): Consider raising exception for read error.
+  required MojoResult result;
+  ArrayBuffer buffer;
+  sequence<MojoHandle> handles;
+};