* Convert AddonManager to TypeScript.

* Convert PubSub (not PubSubClient) to TypeScript.
* Convert StagingSelector to TypeScript.
* Make sure to add ExperimentManager's events to the global interface.

src/staging.tsx

@@ -0,0 +1,73 @@
+'use strict';
+
+// ============================================================================
+// Staging Selector
+// ============================================================================
+
+import Module, { GenericModule } from 'utilities/module';
+import { API_SERVER, SERVER, STAGING_API, STAGING_CDN } from './utilities/constants';
+import type SettingsManager from './settings';
+
+declare module 'utilities/types' {
+	interface ModuleMap {
+		staging: StagingSelector;
+	}
+	interface ModuleEventMap {
+		staging: StagingEvents;
+	}
+	interface SettingsTypeMap {
+		'data.use-staging': boolean;
+	}
+}
+
+type StagingEvents = {
+	':updated': [api: string, cdn: string];
+}
+
+export default class StagingSelector extends Module<'staging', StagingEvents> {
+
+	// Dependencies
+	settings: SettingsManager = null as any;
+
+	// State
+	api: string = API_SERVER;
+	cdn: string = SERVER;
+	active: boolean = false;
+
+	constructor(name?: string, parent?: GenericModule) {
+		super(name, parent);
+
+		this.inject('settings');
+
+		this.settings.add('data.use-staging', {
+			default: false,
+			ui: {
+				path: 'Debugging > Data Sources >> Staging @{"sort": -1}',
+				force_seen: true,
+				title: 'Use staging as data source.',
+				component: 'setting-check-box'
+			}
+		});
+
+		this.updateStaging(false);
+	}
+
+	/** @internal */
+	onEnable() {
+		this.settings.getChanges('data.use-staging', this.updateStaging, this);
+	}
+
+	private updateStaging(val: boolean) {
+		this.active = val;
+
+		this.api = val
+			? STAGING_API
+			: API_SERVER;
+
+		this.cdn = val
+			? STAGING_CDN
+			: SERVER;
+
+		this.emit(':updated', this.api, this.cdn);
+	}
+}