Merge "Allow ve.init.Platforms to asynchronously initialize themselves"

modules/ve-mw/init/ve.init.mw.Target.js

@@ -244,6 +244,8 @@ ve.init.mw.Target.onModulesReady = function () {
 	}
 	// Dereference the callbacks
 	this.pluginCallbacks = [];
+	// Add the platform promise to the list
+	promises.push( ve.init.platform.getInitializedPromise() );
 	// Create a master promise tracking all the promises we got, and wait for it
 	// to be resolved
 	$.when.apply( $, promises ).done( this.modulesReady.resolve ).fail( this.modulesReady.reject );

modules/ve/init/ve.init.Platform.js

@@ -127,3 +127,29 @@ ve.init.Platform.prototype.getUserLanguages = function () {
 ve.init.Platform.prototype.getMediaSources = function () {
 	throw new Error( 've.init.Platform.getMediaSources must be overridden in subclass' );
 };
+
+/**
+ * Initialize the platform. The default implementation is to do nothing and return a resolved
+ * promise. Subclasses should override this if they have asynchronous initialization work to do.
+ *
+ * External callers should not call this. Instead, call #getInitializedPromise.
+ *
+ * @private
+ * @returns {jQuery.Promise} Promise that will be resolved once initialization is done
+ */
+ve.init.Platform.prototype.initialize = function () {
+	return $.Deferred().resolve().promise();
+};
+
+/**
+ * Get a promise to track when the platform has initialized. The platform won't be ready for use
+ * until this promise is resolved.
+ *
+ * @returns {jQuery.Promise} Promise that will be resolved once the platform is ready
+ */
+ve.init.Platform.prototype.getInitializedPromise = function () {
+	if ( !this.initialized ) {
+		this.initialized = this.initialize();
+	}
+	return this.initialized;
+};