Make Chart.layout(Service) importable (chartjs#5113)

Rename (and deprecate) `Chart.layoutService` to `Chart.layout` and make it importable.

src/chart.js

@@ -12,14 +12,14 @@ Chart.defaults = require('./core/core.defaults');
 Chart.Element = require('./core/core.element');
 Chart.elements = require('./elements/index');
 Chart.Interaction = require('./core/core.interaction');
+Chart.layout = require('./core/core.layout');
 Chart.platform = require('./platforms/platform');
 Chart.Ticks = require('./core/core.ticks');
 
 require('./core/core.plugin')(Chart);
 require('./core/core.animation')(Chart);
 require('./core/core.controller')(Chart);
 require('./core/core.datasetController')(Chart);
-require('./core/core.layoutService')(Chart);
 require('./core/core.scaleService')(Chart);
 require('./core/core.scale')(Chart);
 require('./core/core.tooltip')(Chart);
@@ -77,3 +77,12 @@ if (typeof window !== 'undefined') {
  * @private
  */
 Chart.canvasHelpers = Chart.helpers.canvas;
+
+/**
+ * Provided for backward compatibility, use Chart.layout instead.
+ * @namespace Chart.layoutService
+ * @deprecated since version 2.8.0
+ * @todo remove at version 3
+ * @private
+ */
+Chart.layoutService = Chart.layout;

src/core/core.controller.js

@@ -3,6 +3,7 @@
 var defaults = require('./core.defaults');
 var helpers = require('../helpers/index');
 var Interaction = require('./core.interaction');
+var layout = require('./core.layout');
 var platform = require('../platforms/platform');
 
 module.exports = function(Chart) {
@@ -46,7 +47,7 @@ module.exports = function(Chart) {
 		var newOptions = chart.options;
 
 		helpers.each(chart.scales, function(scale) {
-			Chart.layoutService.removeBox(chart, scale);
+			layout.removeBox(chart, scale);
 		});
 
 		newOptions = helpers.configMerge(
@@ -435,7 +436,7 @@ module.exports = function(Chart) {
 				return;
 			}
 
-			Chart.layoutService.update(this, this.width, this.height);
+			layout.update(this, this.width, this.height);
 
 			/**
 			 * Provided for backward compatibility, use `afterLayout` instead.