Enable VP9 in MP4 by default

media/base/media_switches.cc

Index: media/base/media_switches.cc
diff --git a/media/base/media_switches.cc b/media/base/media_switches.cc
index e04993eedc7ecbfc1619a39d47a8d3262ca0bf5d..3fcad61a4e21329e69997f2967776ad3b8d12b80 100644
--- a/media/base/media_switches.cc
+++ b/media/base/media_switches.cc
@@ -138,10 +138,6 @@ const char kVideoUnderflowThresholdMs[] = "video-underflow-threshold-ms";
 const char kDisableRTCSmoothnessAlgorithm[] =
     "disable-rtc-smoothness-algorithm";
 
-// Enables demuxing of vp9 in mp4. Note that this flag will not have any effect
-// if MP4 demuxing is not enabled in the build.
-const char kEnableVp9InMp4[] = "enable-vp9-in-mp4";
-
 // Force media player using SurfaceView instead of SurfaceTexture on Android.
 const char kForceVideoOverlays[] = "force-video-overlays";