Adds Mojo IDL.

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

Index: third_party/WebKit/Source/core/mojo/MojoWriteMessageOptions.idl
diff --git a/third_party/WebKit/Source/core/mojo/MojoWriteMessageOptions.idl b/third_party/WebKit/Source/core/mojo/MojoWriteMessageOptions.idl
new file mode 100644
index 0000000000000000000000000000000000000000..25ffc9d8fe3568f569d4ead00d93c266c5a559dc
--- /dev/null
+++ b/third_party/WebKit/Source/core/mojo/MojoWriteMessageOptions.idl
@@ -0,0 +1,8 @@
+// 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.
+
+dictionary MojoWriteMessageOptions {

[yzshen1, 2017/01/12 23:38:35]

IMO, it makes sense to have separate parameters instead of a single dictionary:
- API like MojoWriteMessage is unlikely to change. If we need any major change
to the paramters, we will have a new method instead.
- Calling method with a dictionary is more verbose. For example:
    handle.writeMessage({buffer: someBuffer, handles: someHandles});
  versus
    handle.writeMessage(someBuffer, someHandles);

WDYT?

[alokp, 2017/01/13 01:07:56]

I do not have strong opinions on this. I guess this is a question for jbroman@
who initially suggested adding the dictionary.

[jbroman, 2017/01/13 19:25:59]

I don't believe I insisted on a dictionary for these particular parameters. I
mostly want:
- flags to be in a dictionary instead of numeric constants
- APIs to be designed in such a way that we could add more arguments if needed
in the future.

|buffer| and |handles| seem like core enough arguments that they can live
outside the dictionary. Since there are no other options right now, the
dictionary can go away (and can be added as a trailing optional argument if we
do need more options in the future).
i.e., if in the future there _are_ write flags, then we would be able to add a
dictionary, with syntax like:

handle.writeMessage(someBuffer, someHandles, { highPriority: true });  // or
whatever options may be added

[alokp, 2017/01/13 23:40:31]

The new patch removes MojoWriteMessageOptions. It also renames
MojoReadMessageOptions -> MojoReadMessageFlags and MojoWatchOptions ->
MojoHandleSignals to be consistent with C API.

+  BufferSource buffer;
+  sequence<MojoHandle> handles;
+};