What steps will reproduce the problem?
1. Turn off network connectivity
2. Call AuthorizationCodeWPInstalledApp.AuthorizeAsync(string.Empty, 
CancellationToken.None)
3. ArgumentNullException is thrown at 
WebAuthenticationBrokerUserControl.xaml.cs#OnBrowserNavigationFailed

Line 69:
tcsAuthorizationCodeResponse.SetException(e.Exception);

What is the expected output? What do you see instead?
Should not set exception if the exception is null. Also, I can't seem to find a 
way to catch that exception from the app when using this API.


What version of the product are you using? Google.Apis.Auth.1.6.0.1-beta
What is your operating system? Windows 8
What is your IDE? Visual Studio 2013
What is the .NET framework version? .Net framework for WinPhone 8

Please provide any additional information below.