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

extensions/browser/api/cast_channel/cast_channel_api.cc

Index: extensions/browser/api/cast_channel/cast_channel_api.cc
diff --git a/extensions/browser/api/cast_channel/cast_channel_api.cc b/extensions/browser/api/cast_channel/cast_channel_api.cc
index b8fd3b2b64e75a17da811befc06427924d633d79..910788af0757bb9617291926d64566fad888654f 100644
--- a/extensions/browser/api/cast_channel/cast_channel_api.cc
+++ b/extensions/browser/api/cast_channel/cast_channel_api.cc
@@ -12,6 +12,7 @@
 #include <string>
 #include <utility>
 
+#include "base/guid.h"
 #include "base/json/json_writer.h"
 #include "base/lazy_instance.h"
 #include "base/memory/ptr_util.h"
@@ -242,8 +243,7 @@ void CastChannelAsyncApiFunction::SetResultFromChannelInfo(
 }
 
 CastChannelOpenFunction::CastChannelOpenFunction()
-    : new_channel_id_(0) {
-}
+    : new_channel_id_(0), nonce_(base::GenerateGUID()) {}
 
 CastChannelOpenFunction::~CastChannelOpenFunction() { }
 
@@ -317,7 +317,8 @@ void CastChannelOpenFunction::AsyncWorkStart() {
                                               : kDefaultConnectTimeoutMillis),
         liveness_timeout_ > base::TimeDelta(), api_->GetLogger(),
         connect_info.capabilities.get() ? *connect_info.capabilities
-                                        : CastDeviceCapability::NONE);
+                                        : CastDeviceCapability::NONE,
+        nonce_);
   }
   new_channel_id_ = AddSocket(socket);
   api_->GetLogger()->LogNewSocketEvent(*socket);