Create RtcEventLogEncoderLegacy

webrtc/logging/rtc_event_log/encoder/rtc_event_log_encoder.h

Index: webrtc/logging/rtc_event_log/encoder/rtc_event_log_encoder.h
diff --git a/webrtc/logging/rtc_event_log/encoder/rtc_event_log_encoder.h b/webrtc/logging/rtc_event_log/encoder/rtc_event_log_encoder.h
new file mode 100644
index 0000000000000000000000000000000000000000..b57af919872a6ab97a0207b224bad9a03457d90f
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+++ b/webrtc/logging/rtc_event_log/encoder/rtc_event_log_encoder.h
@@ -0,0 +1,28 @@
+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_LOGGING_RTC_EVENT_LOG_ENCODER_RTC_EVENT_LOG_ENCODER_H_
+#define WEBRTC_LOGGING_RTC_EVENT_LOG_ENCODER_RTC_EVENT_LOG_ENCODER_H_
+
+#include <string>
+
+#include "webrtc/logging/rtc_event_log/events/rtc_event.h"
+
+namespace webrtc {
+class RtcEventLogEncoder {
+ public:
+  virtual ~RtcEventLogEncoder() = default;
+
+  virtual std::string Encode(const RtcEvent& event) = 0;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_LOGGING_RTC_EVENT_LOG_ENCODER_RTC_EVENT_LOG_ENCODER_H_