javascriptChannelNames property Null safety

Set<String> javascriptChannelNames
final

The initial set of JavaScript channels that are configured for this webview.

For each value in this set the platform's webview should make sure that a corresponding property with a postMessage method is set on window. For example for a JavaScript channel named Foo it should be possible for JavaScript code executing in the webview to do

Foo.postMessage('hello');

Implementation

// TODO(amirh): describe what should happen when postMessage is called once that code is migrated
// to PlatformWebView.
final Set<String> javascriptChannelNames;