Camera: Fix crash during open and close camera

When we open camera for the second time after opening camera,
switching to camcorder and exit camcorder rapidly, crash will
be observed. It's due to the assertion of double open.
When app receives pause event, it should cancel the switch
animation, as we as it's listener.

Change-Id: Id351d3e5db63c54646d592b728a4624e3d6e1211