Configuring timeout on an existing Task using Extension method

I was using SignalR IHubProxy and wanted to configure timeout on the task returned.
The problem is that I didn't create this task and hence couldn't set a timeout using cancellation token, etc
Thanks to the support from SignalR team, I was able to set Timeout using Extension method
Below is the sample code

public static class TaskExtensions

{

    public static async Task<T> TimeoutAfter<T>(this Task<T> task, TimeSpan timeout)

    {

        var delayTask = Task.Delay(timeout);

        var finishedFirst = await Task.WhenAny(task, delayTask);

        if (finishedFirst != delayTask)

        {

            // Task finished before the timeout

            return ((Task<T>)finishedFirst).Result;

        } 

        // Task didn't finish before the timeout

        // Note: Technically the task wasn't canceled at all, it's still running but there's no

        //       way to stop it from here but the caller can handle this exception and retrieve

        //       the task from the InnerException.Task property if further action is desired.

        throw new TaskCanceledException(

            "The task didn't complete within the specified time.",

            new TaskCanceledException(task));

    } 

    private static async void ExampleUsage()

    {

        var exampleAsync = new Func<Task<int>>(() => Task.FromResult(1)); 

        try

        {

            var result = await exampleAsync().TimeoutAfter(TimeSpan.FromSeconds(10));

        }

        catch (TaskCanceledException)

        {

            // The task timed out

        }

    }

}