[ Merged from http://go/wvgerrit/152493 ]
Replace struct with class for WVDrmFactory, WVCryptoPlugin
and WVDrmPlugin.
Also fix build_all_unit_tests.sh, hidl_metrics_adapter_unittest
has been renamed to hal_metrics_adapter_unittest.
Test: unit tests
Test: Google TV and Netflix
Test: atest GtsMediaTestCases
Bug: 216717460
Change-Id: I92b15510267e8f37058845be760a6ec6241bc5d7