js/libs/ember-data.js
function(type) {
    var adapter = this.adapterFor(type);

    if (adapter && adapter.generateIdForRecord) {
      return adapter.generateIdForRecord(this);
    }

    return null;
  }
function(type) {
    var adapter = this.adapterFor(type);

    if (adapter && adapter.generateIdForRecord) {
      return adapter.generateIdForRecord(this);
    }

    return null;
  }
If possible, this method asks the adapter to generate an ID for
a newly created record.

@method _generateId
@private
@param {String} type
@returns {String} if the adapter can generate one, an ID