Revert of [cast_channel] Move cast_channel related files from //extensions to //components

components/cast_channel/cast_message_util.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 COMPONENTS_CAST_CHANNEL_CAST_MESSAGE_UTIL_H_
-#define COMPONENTS_CAST_CHANNEL_CAST_MESSAGE_UTIL_H_
-
-#include <string>
-
-namespace cast_channel {
-
-class AuthContext;
-class CastMessage;
-class DeviceAuthMessage;
-
-// Checks if the contents of |message_proto| are valid.
-bool IsCastMessageValid(const CastMessage& message_proto);
-
-// Returns a human readable string for |message_proto|.
-std::string CastMessageToString(const CastMessage& message_proto);
-
-// Returns a human readable string for |message|.
-std::string AuthMessageToString(const DeviceAuthMessage& message);
-
-// Fills |message_proto| appropriately for an auth challenge request message.
-// Uses the nonce challenge in |auth_context|.
-void CreateAuthChallengeMessage(CastMessage* message_proto,
-                                const AuthContext& auth_context);
-
-// Returns whether the given message is an auth handshake message.
-bool IsAuthMessage(const CastMessage& message);
-
-}  // namespace cast_channel
-
-#endif  // COMPONENTS_CAST_CHANNEL_CAST_MESSAGE_UTIL_H_