[ Merge of http://go/wvgerrit/22237 ]
This only changes the existing fields of the policy.
License::Policy::license_duration_seconds represents the end time
(relative to the license start time) that the license can be used.
This overriding other times if this is earlier.
License::Policy::rental_duration_seconds represents the end time
(relative to the license start time) that the license can be used
before playback starts. Once playback starts, this no longer applies.
License::Policy::playback_duration_seconds represents the end time
(relative to the playback start time) that the license can be used after
playback has started.
b/34211676
Test: Ran new unittests and reran old tests. All tests other than some
oemcrypto, request_license_test passed. Those tests failed with or
without this CL.
Change-Id: I34e7e39a7ab864300806c557b480f093aec8e545