Fix nondeterministic behavior in rtc_event_log_visualizer caused by uninitialized variables.

Bug: webrtc:11566
Change-Id: I10dcb84c8e7e231fe24dc322a0359742dded05bb
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/176515
Commit-Queue: Björn Terelius <terelius@webrtc.org>
Reviewed-by: Andrey Logvin <landrey@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31471}
diff --git a/rtc_tools/rtc_event_log_visualizer/analyzer.cc b/rtc_tools/rtc_event_log_visualizer/analyzer.cc
index cb270c1..287fbe2 100644
--- a/rtc_tools/rtc_event_log_visualizer/analyzer.cc
+++ b/rtc_tools/rtc_event_log_visualizer/analyzer.cc
@@ -1469,8 +1469,10 @@
     }
 
    private:
-    uint32_t last_bitrate_bps_;
-    bool bitrate_updated_;
+    // We don't know the start bitrate, but assume that it is the default 300
+    // kbps.
+    uint32_t last_bitrate_bps_ = 300000;
+    bool bitrate_updated_ = false;
   };
 
   std::multimap<int64_t, const RtpPacketType*> incoming_rtp;