FLAG_ACTIVITY_MULTIPLE_TASK
总结：
1、使用改标记，需要自行管理Activity
2、需要与FLAG_ACTIVITY_NEW_DOCUMENT或者FLAG_ACTIVITY_NEW_TASK共同使用
/**
* This flag is used to create a new task and launch an activity into it.
新建任务，并在其中启动activity
* This flag is always paired with either {@link #FLAG_ACTIVITY_NEW_DOCUMENT}
* or {@link #FLAG_ACTIVITY_NEW_TASK}.
这个标记通常与FLAG_ACTIVITY_NEW_DOCUMENT或者FLAG_ACTIVITY_NEW_TASK共同使用
In both cases these flags alone would
* search through existing tasks for ones matching this Intent.
FLAG_ACTIVITY_NEW_TASK和FLAG_ACTIVITY_NEW_DOCUMENT，单独使用将会搜索已存在的任务链，来获取匹配当前Intent的任务
Only if no such
* task is found would a new task be created.
只有找不到符合要求的任务，才会创建新的任务
When paired with
* FLAG_ACTIVITY_MULTIPLE_TASK both of these behaviors are modified to skip
* the search for a matching task and unconditionally start a new task.
当结合FLAG_ACTIVITY_MULTIPLE_TASK使用，就会跳过搜索符合要求的任务，无条件的启动一个新任务
*
* <strong>When used with {@link #FLAG_ACTIVITY_NEW_TASK} do not use this
* flag unless you are implementing your own
* top-level application launcher.
当使用了FLAG_ACTIVITY_NEW_TASK，不要使用这个标记，除非你要实现你自己的顶层应用启动器
</strong> Used in conjunction with
* {@link #FLAG_ACTIVITY_NEW_TASK} to disable the
* behavior of bringing an existing task to the foreground.
结合FLAG_ACTIVITY_NEW_TASK可以实现禁止调用存在的后台任务进入前台的目的
When set,
* a new task is <em>always</em> started to host the Activity for the
* Intent, regardless of whether there is already an existing task running
* the same thing.
当设置这个标记后，无论是否有已经存在的做相同事情的任务，始终新建新的任务来容纳Acitvity
*
* <p><strong>Because the default system does not include graphical task management,
* you should not use this flag unless you provide some way for a user to
* return back to the tasks you have launched.</strong>
由于默认系统没有包含图形化的任务管理器，不建议使用这个标记，除非提供某种方式让用户能够返回你已经启动的相关任务
*
* See {@link #FLAG_ACTIVITY_NEW_DOCUMENT} for details of this flag's use for
* creating new document tasks.
参考FLAG_ACTIVITY_NEW_DOCUMENT链接，来获取更多创建新文档任务的使用说明
*
* <p>This flag is ignored if one of {@link #FLAG_ACTIVITY_NEW_TASK} or
* {@link #FLAG_ACTIVITY_NEW_DOCUMENT} is not also set.
不与FLAG_ACTIVITY_NEW_DOCUMENT、FLAG_ACTIVITY_NEW_TASK任意一个合用，这个标记将会失效
*
* <p>See
* <a href="{@docRoot}guide/topics/fundamentals/tasks-and-back-stack.html">Tasks and Back
* Stack</a> for more information about tasks.
参考链接任务链和回退栈，获取更多关于任务链的信息
*
* @see #FLAG_ACTIVITY_NEW_DOCUMENT
* @see #FLAG_ACTIVITY_NEW_TASK
*/
