https://msdn.microsoft.com/en-us/library/windows/desktop/br211474.aspx
Launching, resuming, and background tasks ： https://msdn.microsoft.com/en-us/library/windows/apps/Mt227652.aspx
App lifecycle: https://msdn.microsoft.com/en-us/library/windows/apps/mt243287.aspx
当应用处于 NotRunning 状态并且用户点击开始屏幕或应用程序列表上的应用磁贴时，将启动应用。应用可能处于 NotRunning 状态，原因有：它从未启动、它运行后出现了故障，或者它被暂停后无法保留在内存中而被系统终止。启动与激活不同。激活是指通过合约或扩展（例如“搜索”合约）激活你的应用。
当启动应用时（包括当应用当前在内存中暂停时），调用 OnLaunched 方法。LaunchActivatedEventArgs 参数包含你的应用之前的状态和激活参数。
Handle app prelaunch： https://msdn.microsoft.com/en-us/library/windows/apps/mt593297.aspx
Handle app activation：https://msdn.microsoft.com/en-us/library/windows/apps/mt574274.aspx
Handle app suspend：https://msdn.microsoft.com/en-us/library/windows/apps/mt574277.aspx
Handle app resume：https://msdn.microsoft.com/en-us/library/windows/apps/mt574276.aspx
Support your app with background tasks： https://msdn.microsoft.com/en-us/library/windows/apps/mt299103.aspx
Guidelines for background tasks： https://msdn.microsoft.com/en-us/library/windows/apps/mt187310.aspx
Create and register a background task：https://msdn.microsoft.com/en-us/library/windows/apps/mt299100.aspx
