Move StreamConfig into its own file

webrtc/logging/rtc_event_log/rtc_stream_config.cc

+/*
+ *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/logging/rtc_event_log/rtc_stream_config.h"
+
+namespace webrtc {
+namespace rtclog {
+
+StreamConfig::StreamConfig() {}
+
+StreamConfig::~StreamConfig() {}
+
+StreamConfig::Codec::Codec(const std::string& payload_name,
+                           int payload_type,
+                           int rtx_payload_type)
+        : payload_name(payload_name),
+          payload_type(payload_type),
+          rtx_payload_type(rtx_payload_type) {}
+
+
+}  // namespace rtclog
+}  // namespace webrtc