Extensions: Move cast_channel and hid APIs to extensions/.

chrome/browser/extensions/api/cast_channel/cast_auth_util.h

-// Copyright 2013 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 CHROME_BROWSER_EXTENSIONS_API_CAST_CHANNEL_CAST_AUTH_UTIL_H_
-#define CHROME_BROWSER_EXTENSIONS_API_CAST_CHANNEL_CAST_AUTH_UTIL_H_
-
-#include <string>
-
-namespace extensions {
-namespace api {
-namespace cast_channel {
-
-class CastMessage;
-
-// Authenticates the given |challenge_reply|:
-// 1. Signature contained in the reply is valid.
-// 2. Certficate used to sign is rooted to a trusted CA.
-bool AuthenticateChallengeReply(const CastMessage& challenge_reply,
-                                const std::string& peer_cert);
-
-}  // namespace cast_channel
-}  // namespace api
-}  // namespace extensions
-
-#endif  // CHROME_BROWSER_EXTENSIONS_API_CAST_CHANNEL_CAST_AUTH_UTIL_H_