Update test updates and known issues to ChangeLog

Merge from Widevine repo of http://go/wvgerrit/169075

Merged from https://widevine-internal-review.googlesource.com/167677

Bug: 275264353
Test: luci tests
Change-Id: I247e5fd73ad53d526a662badbca43520fed5f1bd

libwvdrmengine/oemcrypto/CHANGELOG.md

@@ -18,6 +18,24 @@ have been added since the last release.  Major changes are described in more
 detail below in individual sections, followed by a consolidated list of minor
 changes.
 
+### OEMCrypto Unit Tests
+
+The unit tests have been updated to test all v18.1 functionality.
+
+We have also refactored the unit tests into several files grouped by category.
+
+Previously, the unit tests modifed the `GTEST_FILTER` in the file
+`oec_device_features.cpp` in order to skip tests of functionality. For example
+keybox tests are skipped for devices that use Provisioning 4.0. We have begun
+replacing the modification of the `GTEST_FILTER` with the GTest macro
+`GTEST_SKIP`. Previously, skipped tests would not show up on the list of running
+tests in stdout. Now, any skipped test will start to run, and then a message
+will explain why it is being skipped. A list of skipped tests will be listed to
+stdout at the end of the test run.
+
+The seed corpus for the oemcrypto fuzz tests has been updated using the updated
+unit tests.
+
 ### REE-side hooks
 
 In oemcrypto/opk/serialization/ree/GEN_oemcrypto_api.c, new ifdef checks have
@@ -166,6 +184,9 @@ OS.
   occasionally (1/100) fail. The exact cause is unknown, but it appears to be
   due to an edge case in the implementation of
   WPTI_GenerateRandomCertificateKeyPair().
+- The OPK does not support Cast Receiver functionality when using Provisioning
+  4.0.
+- The OPK does not yet support MediaCAS functionality.
 
 ## [OPK Version 17.1.1][v17.1+opk-v17.1.1]
 
@@ -344,3 +365,4 @@ Public release for OEMCrypto API and ODK library version 16.4.
 [v17+test-updates+opk+mk]: https://widevine-partner.googlesource.com/oemcrypto/+/refs/tags/v17+test-updates+opk+mk
 [v17.1]: https://widevine-partner.googlesource.com/oemcrypto/+/refs/tags/v17.1
 [v17.1+opk-v17.1.1]: https://widevine-partner.googlesource.com/oemcrypto/+/refs/tags/v17.1+opk-v17.1.1
+[v18.1]: https://widevine-partner.googlesource.com/oemcrypto/+/refs/tags/v18.1