Should return true if the specified file doesn't exist

This method is used by MediaPlayerStressTest#doTestVideoPlayback().
When it is forgotten to copy media files into the test device before
doing MediaStressTest, the test would be skipped then it would be
passed. If the method returns true, the test is conducted then it
would be failed.

Change-Id: Iaf2cc541f5dd1b87ee7b2eb210b24af506297885
1 file changed