Summary:
Ref T6559. Adds a "JX.Leader" primitive to replace the synchronization over Flash. This does a couple of things:
- Offers an "onBecomeLeader" event, which we can use to open the WebSocket.
- Offers an "onReceiveMessage" event, which we can use to dispatch notifications and handle requests to play sounds and send desktop notifications.
- Offers a "broadcast()" method, which we can use to send desktop notification and sound requests.
Test Plan:
Added some code like this:
```
if (!statics.leader) {
statics.leader = true;
JX.Leader.listen('onBecomeLeader', function() {
JX.log("This tab is now the leader.");
});
JX.Leader.listen('onReceiveBroadcast', function(message, is_leader) {
JX.log('[' + (is_leader ? 'As Leader' : 'Not Leader') + '] ' + message);
});
JX.Leader.start();
}
```
Then:
- Saw first tab open become leader reliably in Safari, Chrome, Firefox.
- Saw new tab become leader reliably when the first tab was closed.
- Saw broadcast() work as documented and deliver messages with correct leadership-flag and uniqueness.
Reviewers: joshuaspence, btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T6559
Differential Revision: https://secure.phabricator.com/D11235
