[Cast Channel] Add support for nonce challenge to Cast channel authentication.

extensions/browser/api/cast_channel/cast_channel_api.h

Index: extensions/browser/api/cast_channel/cast_channel_api.h
diff --git a/extensions/browser/api/cast_channel/cast_channel_api.h b/extensions/browser/api/cast_channel/cast_channel_api.h
index b526e73e691e71dec22fda7bd2753b3acc4a1fc1..c45839de440eb78c3d8d0041d0633cc847163bab 100644
--- a/extensions/browser/api/cast_channel/cast_channel_api.h
+++ b/extensions/browser/api/cast_channel/cast_channel_api.h
@@ -208,6 +208,9 @@ class CastChannelOpenFunction : public CastChannelAsyncApiFunction {
   base::TimeDelta liveness_timeout_;
   base::TimeDelta ping_interval_;
 
+  // The nonce challenge to send to the Cast receiver.
+  std::string nonce_;

[mark a. foltz, 2017/02/27 23:04:32]

This belongs in CastSocketImpl.  The extension API doesn't need to care about
it.

[ryanchung, 2017/03/01 20:09:47]

Done.

+
   FRIEND_TEST_ALL_PREFIXES(CastChannelOpenFunctionTest, TestParseConnectInfo);
   DISALLOW_COPY_AND_ASSIGN(CastChannelOpenFunction);
 };