Allow EventLogAnalyzer to be created without a valid parsed log

The purpose is to be able to list all possible plots without opening an eventlog.

Bug: None
Change-Id: I947114d59b5ec393357748c0a0f78d95edd63663
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/461421
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Auto-Submit: Per Kjellander <perkj@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#47313}

rtc_tools/rtc_event_log_visualizer/analyzer.cc

diff --git a/rtc_tools/rtc_event_log_visualizer/analyzer.cc b/rtc_tools/rtc_event_log_visualizer/analyzer.cc
index a44d683..5821ad7 100644
--- a/rtc_tools/rtc_event_log_visualizer/analyzer.cc
+++ b/rtc_tools/rtc_event_log_visualizer/analyzer.cc
@@ -47,22 +47,28 @@
   }
   neteq_simulator_ = std::make_unique<LazyNetEqSimulator>(parsed_log_, config_);
 
-  RTC_LOG(LS_INFO) << "Log is "
-                   << (parsed_log_.last_timestamp().ms() -
-                       parsed_log_.first_timestamp().ms()) /
-                          1000
-                   << " seconds long.";
+  if (parsed_log_.first_timestamp().IsFinite() &&
+      parsed_log_.last_timestamp().IsFinite()) {
+    RTC_LOG(LS_INFO) << "Log is "
+                     << (parsed_log_.last_timestamp().ms() -
+                         parsed_log_.first_timestamp().ms()) /
+                            1000
+                     << " seconds long.";
+  }
 }
 
 EventLogAnalyzer::EventLogAnalyzer(const ParsedRtcEventLog& parsed_log,
                                    const AnalyzerConfig& config)
     : parsed_log_(parsed_log), config_(config) {
   neteq_simulator_ = std::make_unique<LazyNetEqSimulator>(parsed_log_, config_);
-  RTC_LOG(LS_INFO) << "Log is "
-                   << (parsed_log_.last_timestamp().ms() -
-                       parsed_log_.first_timestamp().ms()) /
-                          1000
-                   << " seconds long.";
+  if (parsed_log_.first_timestamp().IsFinite() &&
+      parsed_log_.last_timestamp().IsFinite()) {
+    RTC_LOG(LS_INFO) << "Log is "
+                     << (parsed_log_.last_timestamp().ms() -
+                         parsed_log_.first_timestamp().ms()) /
+                            1000
+                     << " seconds long.";
+  }
 }
 
 EventLogAnalyzer::~EventLogAnalyzer() = default;