The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/dfd6eedb468f73fc55e28f02dad2c59a594ab03f

commit dfd6eedb468f73fc55e28f02dad2c59a594ab03f
Author: Kevin Marshall <kmarshall@chromium.org>
Date: Thu Jan 17 05:38:25 2019

[fuchsia] Implement Cast Channel API using Connector/MessagePort.

Add a Cast Channel FIDL service, which bridges FIDL clients and the JS
cast.__platform__.channel API.

Injects cast.__platform__.channel to the document scripting context.
The Cast Channel can be opened, written to, and closed by JS.
The C++ side can write messages to an opened Channel.

Modify OnLoadScriptInjector to use to page commit events as a trigger
for script injection instead of DidClearWindowObject(). Page commits
are guaranteed to occur only once per page load, which is a more useful
event than window object clearing, which happens once for an initial
page load, and then twice for all subsequent navigations.

Enable "castrunner_browsertests" suite for testing bots.

Actual integration into the Cast Runner will take place in a followup
CL.

Bug: 910799
Change-Id: Ie7abdb22b5ed61b62fbbfceac9e466c8d36f10f6
Reviewed-on: https://chromium-review.googlesource.com/c/1357719
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623601}
[modify] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/testing/buildbot/chromium.fyi.json
[modify] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/testing/buildbot/gn_isolate_map.pyl
[modify] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/testing/buildbot/test_suite_exceptions.pyl
[modify] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/testing/buildbot/test_suites.pyl
[modify] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/BUILD.gn
[add] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/app/cast/bindings/cast_channel.cc
[add] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/app/cast/bindings/cast_channel.h
[add] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/app/cast/bindings/cast_channel.js
[add] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/app/cast/bindings/cast_channel_browsertest.cc
[add] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/app/cast/test/data/cast_channel.html
[add] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/app/cast/test/data/cast_channel_reconnect.html
[modify] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/common/named_message_port_connector.js
[add] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/fidl/cast/cast_channel.fidl
[modify] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/renderer/on_load_script_injector.cc
[modify] https://crrev.com/dfd6eedb468f73fc55e28f02dad2c59a594ab03f/webrunner/renderer/on_load_script_injector.h