src/vs/workbench/browser/parts/editor/editorsObserver.ts/EditorsObserver/registerListeners
class EditorsObserver:	private registerListeners(): void {
		this._register(this.storageService.onWillSaveState(() => this.saveState()));
		this._register(this.editorGroupsService.onDidAddGroup(group => this.onGroupAdded(group)));
		this._register(this.editorGroupsService.onDidChangeEditorPartOptions(e => this.onDidChangeEditorPartOptions(e)));

		this.editorGroupsService.whenReady.then(() => this.loadState());
	}