[cast_channel] Make cast_channel related files not depend on "cast_channel.h"

components/cast_channel/cast_channel_enum.cc

+// Copyright 2017 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.
+
+#include "components/cast_channel/cast_channel_enum.h"
+
+#include "base/logging.h"
+
+namespace cast_channel {
+
+#define CAST_CHANNEL_TYPE_TO_STRING(enum) \
+  case enum:                              \
+    return #enum
+
+std::string ReadyStateToString(ReadyState ready_state) {
+  switch (ready_state) {
+    CAST_CHANNEL_TYPE_TO_STRING(ReadyState::NONE);
+    CAST_CHANNEL_TYPE_TO_STRING(ReadyState::CONNECTING);
+    CAST_CHANNEL_TYPE_TO_STRING(ReadyState::OPEN);
+    CAST_CHANNEL_TYPE_TO_STRING(ReadyState::CLOSING);
+    CAST_CHANNEL_TYPE_TO_STRING(ReadyState::CLOSED);
+
+    default:

[imcheng, 2017/05/26 17:43:36]

Maybe get rid of the default case? It will help us catch new enums that we
forget to add here, in compile time.

[zhaobin, 2017/05/27 03:08:38]

Done.

+      NOTREACHED();

[mark a. foltz, 2017/05/26 16:56:42]

Also << "Unknown ready_state " << ready_state

here and below

[zhaobin, 2017/05/27 03:08:38]

Done.

+  }
+}
+
+std::string ChannelErrorToString(ChannelError channel_error) {
+  switch (channel_error) {
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::NONE);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::CHANNEL_NOT_OPEN);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::AUTHENTICATION_ERROR);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::CONNECT_ERROR);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::SOCKET_ERROR);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::TRANSPORT_ERROR);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::INVALID_MESSAGE);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::INVALID_CHANNEL_ID);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::CONNECT_TIMEOUT);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::PING_TIMEOUT);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelError::UNKNOWN);
+
+    default:
+      NOTREACHED();
+  }
+}
+
+std::string ChannelAuthTypeToString(ChannelAuthType channel_auth) {
+  switch (channel_auth) {
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelAuthType::NONE);
+    CAST_CHANNEL_TYPE_TO_STRING(ChannelAuthType::SSL_VERIFIED);
+    default:
+      NOTREACHED();
+  }
+}
+
+}  // namespace cast_channel