Reland: Add BWE plot to event log analyzer.

webrtc/call/rtc_event_log.h

Index: webrtc/call/rtc_event_log.h
diff --git a/webrtc/call/rtc_event_log.h b/webrtc/call/rtc_event_log.h
index 7c72dd5ce995a4443a25af429154c4ce7f651bab..a3359692eb8488dd2796929aaa278476156ee563 100644
--- a/webrtc/call/rtc_event_log.h
+++ b/webrtc/call/rtc_event_log.h
@@ -109,6 +109,34 @@ class RtcEventLog {
                                rtclog::EventStream* result);
 };
 
+// No-op implementation is used if flag is not set, or in tests.
+class RtcEventLogNullImpl final : public RtcEventLog {
+ public:
+  bool StartLogging(const std::string& file_name,
+                    int64_t max_size_bytes) override {
+    return false;
+  }
+  bool StartLogging(rtc::PlatformFile platform_file,
+                    int64_t max_size_bytes) override;
+  void StopLogging() override {}
+  void LogVideoReceiveStreamConfig(
+      const VideoReceiveStream::Config& config) override {}
+  void LogVideoSendStreamConfig(
+      const VideoSendStream::Config& config) override {}
+  void LogRtpHeader(PacketDirection direction,
+                    MediaType media_type,
+                    const uint8_t* header,
+                    size_t packet_length) override {}
+  void LogRtcpPacket(PacketDirection direction,
+                     MediaType media_type,
+                     const uint8_t* packet,
+                     size_t length) override {}
+  void LogAudioPlayout(uint32_t ssrc) override {}
+  void LogBwePacketLossEvent(int32_t bitrate,
+                             uint8_t fraction_loss,
+                             int32_t total_packets) override {}
+};
+
 }  // namespace webrtc
 
 #endif  // WEBRTC_CALL_RTC_EVENT_LOG_H_