Handle corrupted data in Telemetry WebRtcRendering

tools/telemetry/telemetry/web_perf/metrics/webrtc_rendering_stats.py

Index: tools/telemetry/telemetry/web_perf/metrics/webrtc_rendering_stats.py
diff --git a/tools/telemetry/telemetry/web_perf/metrics/webrtc_rendering_stats.py b/tools/telemetry/telemetry/web_perf/metrics/webrtc_rendering_stats.py
index 30be6c82e5d3d5e33ac8abe38361ed117dba3088..55c72d0f46caa39d88a5433ad9508c820100731d 100644
--- a/tools/telemetry/telemetry/web_perf/metrics/webrtc_rendering_stats.py
+++ b/tools/telemetry/telemetry/web_perf/metrics/webrtc_rendering_stats.py
@@ -37,6 +37,7 @@ class TimeStats(object):
     self.rendering_length_error = rendering_length_error
     self.fps = fps
     self.frame_distribution = frame_distribution
+    self.invalid_data = False
 
 
 
@@ -335,6 +336,11 @@ class WebMediaPlayerMsRenderingStats(object):
         continue
 
       cadence = self._GetCadence(relevant_events)
+      if not cadence:
+        stats = TimeStats()
+        stats.invalid_data = True
+        return stats
+
       frame_distribution = self._GetSourceToOutputDistribution(cadence)
       fps = self._GetFpsFromCadence(frame_distribution)