CefSharp v62修改方法(支持.net4.0)

namespace System.Threading.Tasks
{
 public static class TaskEx
 {
 public static TaskAwaiter GetAwaiter(this Task task)
 {
 return new TaskAwaiter(task);
 }
 public static TaskAwaiter<T> GetAwaiter<T>(this Task<T> task)
 {
 return new TaskAwaiter<T>(task);
 }
 }
 public struct TaskAwaiter : INotifyCompletion
 {
 readonly Task task;
 internal TaskAwaiter(Task task)
 {
 this.task = task;
 }
 internal static TaskScheduler TaskScheduler
 {
 get
 {
 if (SynchronizationContext.Current == null)
 return TaskScheduler.Default;
 else
 return TaskScheduler.FromCurrentSynchronizationContext();
 }
 }
 public bool IsCompleted
 {
 get { return task.IsCompleted; }
 }
 public void OnCompleted(Action continuation)
 {
 this.task.ContinueWith(
 delegate (Task task) {
 continuation();
 }, TaskAwaiter.TaskScheduler);
 }
 public void GetResult()
 {
 try
 {
 task.Wait();
 }
 catch (AggregateException ex)
 {
 throw ex.InnerExceptions[0];
 }
 }
 }
 public struct TaskAwaiter<T> : INotifyCompletion
 {
 readonly Task<T> task;
 internal TaskAwaiter(Task<T> task)
 {
 this.task = task;
 }
 public bool IsCompleted
 {
 get { return task.IsCompleted; }
 }
 public void OnCompleted(Action continuation)
 {
 this.task.ContinueWith(
 delegate (Task<T> task) {
 continuation();
 }, TaskAwaiter.TaskScheduler);
 }
 public T GetResult()
 {
 try
 {
 return task.Result;
 }
 catch (AggregateException ex)
 {
 throw ex.InnerExceptions[0];
 }
 }
 }
}
namespace System.Runtime.CompilerServices
{
 public interface INotifyCompletion
 {
 void OnCompleted(Action continuation);
 }
 public interface ICriticalNotifyCompletion : INotifyCompletion
 {
 [SecurityCritical]
 void UnsafeOnCompleted(Action continuation);
 }
 public interface IAsyncStateMachine
 {
 void MoveNext();
 void SetStateMachine(IAsyncStateMachine stateMachine);
 }
 public struct AsyncVoidMethodBuilder
 {
 public static AsyncVoidMethodBuilder Create()
 {
 return new AsyncVoidMethodBuilder();
 }
 public void SetException(Exception exception)
 {
 throw exception;
 }
 public void SetResult()
 {
 }
 public void SetStateMachine(IAsyncStateMachine stateMachine)
 {
 // Should not get called as we don't implement the optimization that this method is used for.
 throw new NotImplementedException();
 }
 public void Start<TStateMachine>(ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine
 {
 stateMachine.MoveNext();
 }
 public void AwaitOnCompleted<TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : INotifyCompletion where TStateMachine : IAsyncStateMachine
 {
 awaiter.OnCompleted(stateMachine.MoveNext);
 }
 public void AwaitUnsafeOnCompleted<TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : ICriticalNotifyCompletion where TStateMachine : IAsyncStateMachine
 {
 awaiter.OnCompleted(stateMachine.MoveNext);
 }
 }
 public struct AsyncTaskMethodBuilder
 {
 TaskCompletionSource<object> tcs;
 public Task Task { get { return tcs.Task; } }
 public static AsyncTaskMethodBuilder Create()
 {
 AsyncTaskMethodBuilder b;
 b.tcs = new TaskCompletionSource<object>();
 return b;
 }
 public void Start<TStateMachine>(ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine
 {
 stateMachine.MoveNext();
 }
 public void SetStateMachine(IAsyncStateMachine stateMachine)
 {
 // Should not get called as we don't implement the optimization that this method is used for.
 throw new NotImplementedException();
 }
 public void AwaitOnCompleted<TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : INotifyCompletion where TStateMachine : IAsyncStateMachine
 {
 awaiter.OnCompleted(stateMachine.MoveNext);
 }
 public void AwaitUnsafeOnCompleted<TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : ICriticalNotifyCompletion where TStateMachine : IAsyncStateMachine
 {
 awaiter.OnCompleted(stateMachine.MoveNext);
 }
 public void SetResult()
 {
 tcs.SetResult(null);
 }
 public void SetException(Exception exception)
 {
 tcs.SetException(exception);
 }
 }
 public struct AsyncTaskMethodBuilder<T>
 {
 TaskCompletionSource<T> tcs;
 public Task<T> Task { get { return tcs.Task; } }
 public static AsyncTaskMethodBuilder<T> Create()
 {
 AsyncTaskMethodBuilder<T> b;
 b.tcs = new TaskCompletionSource<T>();
 return b;
 }
 public void Start<TStateMachine>(ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine
 {
 stateMachine.MoveNext();
 }
 public void SetStateMachine(IAsyncStateMachine stateMachine)
 {
 // Should not get called as we don't implement the optimization that this method is used for.
 throw new NotImplementedException();
 }
 public void AwaitOnCompleted<TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : INotifyCompletion where TStateMachine : IAsyncStateMachine
 {
 awaiter.OnCompleted(stateMachine.MoveNext);
 }
 public void AwaitUnsafeOnCompleted<TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : ICriticalNotifyCompletion where TStateMachine : IAsyncStateMachine
 {
 AwaitOnCompleted(ref awaiter, ref stateMachine);
 }
 public void SetResult(T result)
 {
 tcs.SetResult(result);
 }
 public void SetException(Exception exception)
 {
 tcs.SetException(exception);
 }
 }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace CefSharp
{
 public class TaskEx
 {
 public static Task<T> FromResult<T>(T t)
 {
 return Task.Factory.StartNew<T>(() => t);
 }
 public static Task Run(Action action)
 {
 var tcs = new TaskCompletionSource<object>();
 new Thread(() => {
 try
 {
 action();
 tcs.SetResult(null);
 }
 catch (Exception ex)
 {
 tcs.SetException(ex);
 }
 })
 { IsBackground = true }.Start();
 return tcs.Task;
 }
 public static Task<TResult> Run<TResult>(Func<TResult> function)
 {
 var tcs = new TaskCompletionSource<TResult>();
 new Thread(() =>
 {
 try
 {
 tcs.SetResult(function());
 }
 catch (Exception ex)
 {
 tcs.SetException(ex);
 }
 })
 { IsBackground = true }.Start();
 return tcs.Task;
 }
 public static Task Delay(int milliseconds)
 {
 var tcs = new TaskCompletionSource<object>();
 var timer = new System.Timers.Timer(milliseconds) { AutoReset = false };
 timer.Elapsed += delegate { timer.Dispose(); tcs.SetResult(null); };
 timer.Start();
 return tcs.Task;
 }
 }
}