src/vs/workbench/services/preferences/browser/keybindingsEditorModel.ts/KeybindingsEditorModel/filterBySource
class KeybindingsEditorModel:	private filterBySource(keybindingItems: IKeybindingItem[], searchValue: string): IKeybindingItem[] {
		if (/@source:\s*default/i.test(searchValue)) {
			return keybindingItems.filter(k => k.source === SOURCE_DEFAULT);
		}
		if (/@source:\s*user/i.test(searchValue)) {
			return keybindingItems.filter(k => k.source === SOURCE_USER);
		}
		if (/@source:\s*extension/i.test(searchValue)) {
			return keybindingItems.filter(k => k.source === SOURCE_EXTENSION);
		}
		return keybindingItems;
	}