[FP5-2896] [Desktop moke]The application interface in the recent interface is blank after disconnect the second screen

* Root Cause
  disconnet desktop Task snapshot is null
* Solution
  set TaskView gone when snapshot is null
* Test Steps
  test Desktop
* Test Result
  pass

Change-Id: I92e695ed2b020aeaba3e7679f9094bf71785a6d7
1 file changed