DrmEngine | Wrap Timeout in Promise
DrmEngine | Wrap Timeout in Promise

There are two times that timeouts are used in the DrmEngine. In
an attempt to make it easier to read, this change creates a function
that wraps the timeout specific code in a promise so that the call
sites just need to wait on a promise.

Change-Id: I02008b0b5afd11be877a422a4a7b93a0e5b8ea8e

tvoli/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,TheModMaker/shaka-player,tvoli/shaka-player,TheModMaker/shaka-player,TheModMaker/shaka-player,tvoli/shaka-player,TheModMaker/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player