[Video] Fix keyframe distance average calculations.

media/base/pipeline_status.h

Index: media/base/pipeline_status.h
diff --git a/media/base/pipeline_status.h b/media/base/pipeline_status.h
index df5263148bc68e8a2c8a12cc2ba9fee3d311e671..b393c79f3bdbf0b5993e240a9b0c69ff70836df7 100644
--- a/media/base/pipeline_status.h
+++ b/media/base/pipeline_status.h
@@ -10,6 +10,7 @@
 
 #include "base/callback.h"
 #include "base/time/time.h"
+#include "media/base/timestamp_constants.h"
 
 namespace media {
 
@@ -59,7 +60,7 @@ struct PipelineStatistics {
   uint32_t video_frames_dropped = 0;
   int64_t audio_memory_usage = 0;
   int64_t video_memory_usage = 0;
-  base::TimeDelta video_keyframe_distance_average;
+  base::TimeDelta video_keyframe_distance_average = kNoTimestamp;
 };
 
 // Used for updating pipeline statistics; the passed value should be a delta