If duration of media source is unknown then return NaN.

content/renderer/media/android/webmediaplayer_android.h

Index: content/renderer/media/android/webmediaplayer_android.h
diff --git a/content/renderer/media/android/webmediaplayer_android.h b/content/renderer/media/android/webmediaplayer_android.h
index bf290b71229ca958d8c356398b03be1238f6589e..e0bf0a1c984e8892bd1f87d2559e0103b170c030 100644
--- a/content/renderer/media/android/webmediaplayer_android.h
+++ b/content/renderer/media/android/webmediaplayer_android.h
@@ -427,6 +427,9 @@ class WebMediaPlayerAndroid : public blink::WebMediaPlayer,
   // Only used for the VIDEO_HOLE logic.
   bool needs_external_surface_;
 
+  // Whether valid metadata are available
+  bool has_valid_metadata_;
+
   // A pointer back to the compositor to inform it about state changes. This is
   // not NULL while the compositor is actively using this webmediaplayer.
   cc::VideoFrameProvider::Client* video_frame_provider_client_;