Rolling AppRTC in AppRTC test 6a3ade345..c2179d16a.

This updates the version of AppRTC we're running against.

BUG=None

Review URL: https://codereview.chromium.org/1219013004.
diff --git a/DEPS b/DEPS
index 0d8f319..2884794 100644
--- a/DEPS
+++ b/DEPS
@@ -8,7 +8,7 @@
 
 deps = {
   'apprtc':
-    Var('git_url') + '/external/webrtc/apprtc@6a3ade3454743977a91a31d87d08d5674f1ef12c',
+    Var('git_url') + '/external/webrtc/apprtc@c2179d16ae879f4ece4d2838585966e7c029c9d3',
   'webrtc.DEPS/third_party/manifestdestiny':
     Var('git_url') + '/chromium/deps/manifestdestiny.git@46ae53ac463e23bfefec374a81806355ea598ac4',
   'webrtc.DEPS/third_party/mozdownload':