Add method to extract triage alerts from RTC event log analyzer.

Bug: webrtc:11566
Change-Id: I8315895be4fe93513247c49452c50ec23e9d1e11
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/186560
Reviewed-by: Andrey Logvin <landrey@webrtc.org>
Commit-Queue: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32292}

rtc_tools/rtc_event_log_visualizer/alerts.h

@@ -57,6 +57,8 @@ class TriageHelper {
                                PacketDirection direction);
   void Print(FILE* file);
 
+  void ProcessAlerts(std::function<void(int, float, std::string)> f);
+
  private:
   AnalyzerConfig config_;
   std::map<TriageAlertType, TriageAlert> triage_alerts_;