Refactor/reimplement RTC event log triage alerts.

- Moves AnalyzerConfig and helper functions IsAudioSsrc, IsVideoSsrc, IsRtxSsrc, GetStreamNam and GetLayerName to analyzer_common.h
- Moves log_segments() code to rtc_event_log_parser.h
- Moves TriageAlert/Notification code to a new file with a couple of minor fixes to make it less spammy.

Bug: webrtc:11566
Change-Id: Ib33941d8185f7382fc72ed65768e46015e0320de
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/174824
Commit-Queue: Björn Terelius <terelius@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31318}

rtc_tools/rtc_event_log_visualizer/alerts.h

@@ -0,0 +1,86 @@
+/*
+ *  Copyright (c) 2020 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 RTC_TOOLS_RTC_EVENT_LOG_VISUALIZER_ALERTS_H_
+#define RTC_TOOLS_RTC_EVENT_LOG_VISUALIZER_ALERTS_H_
+
+#include <stdio.h>
+
+#include <map>
+#include <string>
+#include <utility>
+
+#include "absl/strings/string_view.h"
+#include "logging/rtc_event_log/rtc_event_log_parser.h"
+#include "rtc_base/constructor_magic.h"
+#include "rtc_tools/rtc_event_log_visualizer/analyzer_common.h"
+
+namespace webrtc {
+
+enum class TriageAlertType {
+  kUnknown = 0,
+  kIncomingRtpGap,
+  kOutgoingRtpGap,
+  kIncomingRtcpGap,
+  kOutgoingRtcpGap,
+  kIncomingSeqNumJump,
+  kOutgoingSeqNumJump,
+  kIncomingCaptureTimeJump,
+  kOutgoingCaptureTimeJump,
+  kOutgoingHighLoss,
+  kLast,
+};
+
+struct TriageAlert {
+  TriageAlertType type = TriageAlertType::kUnknown;
+  int count = 0;
+  float first_occurence = -1;
+  std::string explanation;
+};
+
+class TriageHelper {
+ public:
+  explicit TriageHelper(const AnalyzerConfig& config) : config_(config) {}
+
+  void AnalyzeLog(const ParsedRtcEventLog& parsed_log);
+
+  void AnalyzeStreamGaps(const ParsedRtcEventLog& parsed_log,
+                         PacketDirection direction);
+  void AnalyzeTransmissionGaps(const ParsedRtcEventLog& parsed_log,
+                               PacketDirection direction);
+  void Print(FILE* file);
+
+ private:
+  AnalyzerConfig config_;
+  std::map<TriageAlertType, TriageAlert> triage_alerts_;
+
+  void Alert(TriageAlertType type,
+             float time_seconds,
+             absl::string_view explanation) {
+    std::map<TriageAlertType, TriageAlert>::iterator it =
+        triage_alerts_.find(type);
+
+    if (it == triage_alerts_.end()) {
+      TriageAlert alert;
+      alert.type = type;
+      alert.first_occurence = time_seconds;
+      alert.count = 1;
+      alert.explanation = std::string(explanation);
+      triage_alerts_.insert(std::make_pair(type, alert));
+    } else {
+      it->second.count += 1;
+    }
+  }
+  RTC_DISALLOW_COPY_AND_ASSIGN(TriageHelper);
+};
+
+}  // namespace webrtc
+
+#endif  // RTC_TOOLS_RTC_EVENT_LOG_VISUALIZER_ALERTS_H_