message: test(common): TokenExtractor should extend HttpXsrfTokenExtractor in xsrf spec
  PR Close
diff: import {HttpHeaders} from '../src/headers';
  import {HttpRequest} from '../src/request';
  -import {HttpXsrfCookieExtractor, HttpXsrfInterceptor} from '../src/xsrf';
  +import {HttpXsrfCookieExtractor, HttpXsrfInterceptor, HttpXsrfTokenExtractor} from '../src/xsrf';
  import {HttpClientTestingBackend} from '../testing/src/backend';
  -class SampleTokenExtractor {
  - constructor(private token: string|null) {}
  +class SampleTokenExtractor extends HttpXsrfTokenExtractor {
  + constructor(private token: string|null) { super(); }
  getToken(): string|null { return this.token; }
  }
  