编译错误：
Error:(xx,xx) error: package com.google.android.gms.auth does not exist Error:(xx,xx) error: cannot find symbol variable GoogleAuthUtil@H_404_4@
解决方法
GoogleAuthUtil已转移到Google Play服务9.0 SDK中的-auth SDK拆分.
@H_502_8@如果您需要在Android上访问REST API,请在您的build.gradle文件中包含-auth split：
https://developers.google.com/identity/sign-in/android/migration-guide#migrate_from_the_googleauthutil_id_token_flow @H_502_8@还有一个博主,了解更多细节：
http://android-developers.blogspot.com/2016/05/improving-security-and-user-experience.html @H_404_4@ @H_404_4@
compile 'com.google.android.gms:play-services-auth:9.0.0'@H_502_8@否则,我们建议您将应用程序迁移到Google Sign-In API,将安全性和用户体验的最新改进纳入到您的应用程序中. @H_502_8@请阅读迁移指南：
https://developers.google.com/identity/sign-in/android/migration-guide#migrate_from_the_googleauthutil_id_token_flow @H_502_8@还有一个博主,了解更多细节：
http://android-developers.blogspot.com/2016/05/improving-security-and-user-experience.html @H_404_4@ @H_404_4@
