Bug: 19771437 It is a merge of below CLs from Widevine CDM repo: Clean up CdmSession and PolicyEngine testing injection https://widevine-internal-review.googlesource.com/#/c/13700 Refactor WvCdmEventListener handling https://widevine-internal-review.googlesource.com/#/c/13702 Change-Id: I356b90000c056113d394926862b859aab380d305