Adds Mojo IDL.

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

Index: third_party/WebKit/Source/core/mojo/MojoHandle.idl
diff --git a/third_party/WebKit/Source/core/mojo/MojoHandle.idl b/third_party/WebKit/Source/core/mojo/MojoHandle.idl
new file mode 100644
index 0000000000000000000000000000000000000000..2ec0f26acaebb80073dfb776ee1acea363db7ca6
--- /dev/null
+++ b/third_party/WebKit/Source/core/mojo/MojoHandle.idl
@@ -0,0 +1,26 @@
+// 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.
+
+typedef unsigned long MojoHandleSignals;
+typedef unsigned long MojoWriteMessageFlags;
+typedef unsigned long MojoReadMessageFlags;
+
+callback MojoWatchCallback = void (MojoResult result);
+
+interface MojoHandle {
+    const MojoHandleSignals HANDLE_SIGNAL_NONE = 0;
+    const MojoHandleSignals HANDLE_SIGNAL_READABLE = 1;
+    const MojoHandleSignals HANDLE_SIGNAL_WRITABLE = 2;
+    const MojoHandleSignals HANDLE_SIGNAL_PEER_CLOSED = 4;
+
+    const MojoWriteMessageFlags WRITE_MESSAGE_FLAG_NONE = 0;
+
+    const MojoReadMessageFlags READ_MESSAGE_FLAG_NONE = 0;
+    const MojoReadMessageFlags READ_MESSAGE_FLAG_MAY_DISCARD = 1;
+
+    MojoResult close();
+    [CallWith=ScriptState] MojoWatcher watch(MojoHandleSignals signals, MojoWatchCallback callback);

[alokp, 2017/01/09 23:33:10]

Should this return a MojoWatch or an integer that can be cancelled using
MojoHandle::cancelWatch? The latter seems to be more idiomatic.

[jbroman, 2017/01/10 20:46:31]

This could be done with a numbered identifier like setTimeout has (as you
mention), but personally I actually prefer objects for this, rather than having
to maintain a context-wide map.

JavaScript-land would also typically use a dictionary instead of flags for
signals, like MutationObserverInit, maybe:

dictionary MojoWatcherInit {
  optional boolean readable = false;
  optional boolean writable = false;
  optional boolean peerClosed = false;
};

with uses looking like:
handle.watch({ readable: true, writable: true }, result => { ... });

[alokp, 2017/01/11 21:53:02]

Done.

+    MojoResult writeMessage(MojoWriteMessageOptions options);
+    MojoReadMessageResult readMessage(MojoReadMessageOptions options);
+};