Add rtanalytics user to cras group

The rtanalytics process (running as the rtanalytics user) needs to talk to cras for audio capture.

BUG=chromium:831250
TEST=local build
CQ-DEPEND=CL:1008042

Change-Id: I6478ea46cd64159fb591f646f4a0a3c698dd51c7
Reviewed-on: https://chromium-review.googlesource.com/1007982
Commit-Ready: Wei Guan <weigua@chromium.org>
Tested-by: Wei Guan <weigua@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>
diff --git a/profiles/base/accounts/group/cras b/profiles/base/accounts/group/cras
index bdbd47c..eb8c051 100644
--- a/profiles/base/accounts/group/cras
+++ b/profiles/base/accounts/group/cras
@@ -1,4 +1,7 @@
 group:cras
 gid:600
-# The browser runs as chronos, and the power manager needs to check if audio is playing.
-users:chronos,power
+# The browser runs as chronos.
+# The power manager needs to check if audio is playing.
+# The rtanalytics process (running as the rtanalytics user) needs to talk to
+#   cras for audio capture.
+users:chronos,power,rtanalytics