Remove support for the keygen tag

chromecast/BUILD.gn

Index: chromecast/BUILD.gn
diff --git a/chromecast/BUILD.gn b/chromecast/BUILD.gn
index c469ac5730eeab7eb03173fdbde9e8db9c3bd8a9..a6fc83a700ecbc756bbe79a3a349c1e249116b4b 100644
--- a/chromecast/BUILD.gn
+++ b/chromecast/BUILD.gn
@@ -218,15 +218,11 @@ cast_test_group("cast_tests") {
       gtest_excludes = [ "*" ]
     } else if (target_os == "linux" && !is_cast_desktop_build) {
       # Run net_unittests first to avoid random failures due to slow python startup
-      # KeygenHandlerTest.SmokeTest and KeygenHandlerTest.ConcurrencyTest fail due to
-      # readonly certdb (b/8153161)
       # URLRequestTestHTTP.GetTest_ManyCookies takes roughly 55s to run. Increase
       # timeout to 90s from 45s to allow it to pass (b/19821476)
       # ProxyScriptFetcherImplTest.HttpMimeType is flaking (b/19848784)
       # Running a batch of net_unittests has high overhead. Run tests in batches of 50 to reduce number of batches (b/23156294).
       gtest_excludes = [
-        "KeygenHandlerTest.SmokeTest",
-        "KeygenHandlerTest.ConcurrencyTest",
         "ProxyScriptFetcherImplTest.HttpMimeType",
       ]
       args = [