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

extensions/browser/api/cast_channel/cast_channel_api.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef EXTENSIONS_BROWSER_API_CAST_CHANNEL_CAST_CHANNEL_API_H_
 #define EXTENSIONS_BROWSER_API_CAST_CHANNEL_CAST_CHANNEL_API_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 190 matching lines @@
 
   std::unique_ptr<cast_channel::Open::Params> params_;
   // The id of the newly opened socket.
   int new_channel_id_;
   CastChannelAPI* api_;
   std::unique_ptr<net::IPEndPoint> ip_endpoint_;
   cast_channel::ChannelAuthType channel_auth_;
   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);
 };
 
 class CastChannelSendFunction : public CastChannelAsyncApiFunction {
  public:
   CastChannelSendFunction();
 
  protected:
   ~CastChannelSendFunction() override;
@@ skipping 69 matching lines @@
  private:
   DECLARE_EXTENSION_FUNCTION("cast.channel.setAuthorityKeys",
                              CAST_CHANNEL_SETAUTHORITYKEYS)
 
   DISALLOW_COPY_AND_ASSIGN(CastChannelSetAuthorityKeysFunction);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_CAST_CHANNEL_CAST_CHANNEL_API_H_