This is a merge of https://widevine-internal-review.googlesource.com/c/cdm/+/144790 Updated cipher mode to allow playback in v17; Added check for key selection before decrypting. Merge from Widevine repo of http://go/wvgerrit/144779 Fix allow_null for key control iv in L3 v17 Merge from Widevine repo of http://go/wvgerrit/144792 Fix api version check in L3 v17 Test: L3 unit tests Bug: 217145027 Change-Id: I584bd57e26407cbf4d4b94eb1bc5cf80839377be