用的是测试id，在测试admob广告的时候一直获取不到，然后新建了一个demo，将代码拷贝过去，是可以获取到的并且展示的，所以代码方面应该没有问题的

出现了如下的异常：

W/GooglePlayServicesUtil: Google Play services out of date for com.xxx.app.  Requires 212800000 but found 201817022
W/Ads: Not retrying to fetch app settings
W/GoogleApiManager: The service for com.google.android.gms.internal.appset.zzd is not available: ConnectionResult{statusCode=SERVICE_VERSION_UPDATE_REQUIRED, resolution=null, message=null}


D/AppOpenManager: onAdFailedToLoad: 加载开屏广告失败 {
      "Code": 0,
      "Message": "Received error HTTP response code: 400",
      "Domain": "com.google.android.gms.ads",
      "Cause": "null",
      "Response Info": {
        "Response ID": "null",
        "Mediation Adapter Class Name": "",
        "Adapter Responses": []
      }
    }

I/Ads: Ad failed to load : 0


E/chromium: [ERROR:cookie_manager.cc(137)] Strict Secure Cookie policy does not allow setting a secure cookie for http://googleads.g.doubleclick.net/ for apps targeting >= R. Please either use the 'https:' scheme for this URL or omit the 'Secure' directive in the cookie value.