For live streams, we cannot assume that the input decoding timestamp
starts from zero.
Also don't overwrite |normalize_presentation_timestamp| if the user
does not want to enable it for on-demand profile.
Change-Id: I1abe7926e0b25eb11dee021be964d126484d4036
This change also updates the WidevineEncryptionKeySource to be able to support
KeyRotation enabled and disabled requests simultaneously.
Change-Id: I5178cafc0dbabbb64ac9af9969d3bf7d8117a4dd