Converts .NET TPL async task pattern to the APM pattern. See [Stephen Toub's blog post](http://blogs.msdn.com/b/pfxteam/archive/2011/06/27/10179452.aspx)

ApmExtensions.cs

// LICENSED under the Ms-PL (http://opensource.org/licenses/MS-PL)

public static Task<TResult> ToApm<TResult>(this Task<TResult> task, AsyncCallback callback, object state) {
	if (task == null) {
		throw new ArgumentNullException("task");
	}

	if (task.AsyncState == state) {
		if (callback != null) {
			task.ContinueWith(
				(t, cb) => ((AsyncCallback)cb)(t),
				callback,
				CancellationToken.None,
				TaskContinuationOptions.None,
				TaskScheduler.Default);
		}

		return task;
	}

	var tcs = new TaskCompletionSource<TResult>(state);
	task.ContinueWith(
		t => {
			if (t.IsFaulted) {
				tcs.TrySetException(t.Exception.InnerExceptions);
			} else if (t.IsCanceled) {
				tcs.TrySetCanceled();
			} else {
				tcs.TrySetResult(t.Result);
			}

			if (callback != null) {
				callback(tcs.Task);
			}

		},
		CancellationToken.None,
		TaskContinuationOptions.None,
		TaskScheduler.Default);

	return tcs.Task;
}

public static Task ToApm(this Task task, AsyncCallback callback, object state) {
	if (task == null) {
		throw new ArgumentNullException("task");
	}

	if (task.AsyncState == state) {
		if (callback != null) {
			task.ContinueWith(
				(t, cb) => ((AsyncCallback)cb)(t),
				callback,
				CancellationToken.None,
				TaskContinuationOptions.None,
				TaskScheduler.Default);
		}

		return task;
	}

	var tcs = new TaskCompletionSource<object>(state);
	task.ContinueWith(
		t => {
			if (t.IsFaulted) {
				tcs.TrySetException(t.Exception.InnerExceptions);
			} else if (t.IsCanceled) {
				tcs.TrySetCanceled();
			} else {
				tcs.TrySetResult(null);
			}

			if (callback != null) {
				callback(tcs.Task);
			}
		},
		CancellationToken.None,
		TaskContinuationOptions.None,
		TaskScheduler.Default);

	return tcs.Task;
}