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

components/cast_channel/proto/cast_channel.proto

 // 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.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
-package extensions.api.cast_channel;
+package cast_channel;
 
 message CastMessage {
   // Always pass a version of the protocol for future compatibility
   // requirements.
-  enum ProtocolVersion {
-    CASTV2_1_0 = 0;
-  }
+  enum ProtocolVersion { CASTV2_1_0 = 0; }
   required ProtocolVersion protocol_version = 1;
 
   // source and destination ids identify the origin and destination of the
   // message.  They are used to route messages between endpoints that share a
   // device-to-device channel.
   //
   // For messages between applications:
   //   - The sender application id is a unique identifier generated on behalf of
   //     the sender application.
   //   - The receiver id is always the the session id for the application.
@@ skipping 65 matching lines @@
   required ErrorType error_type = 1;
 }
 
 message DeviceAuthMessage {
   // Request fields
   optional AuthChallenge challenge = 1;
   // Response fields
   optional AuthResponse response = 2;
   optional AuthError error = 3;
 }