Don't set V bit in flexible mode

webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc

Index: webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
diff --git a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
index 04bbd161ec699338a2a36ac9a6f912ee39207132..b9efc7e20abba6020727e467f24a86029046e535 100644
--- a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
+++ b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
@@ -485,8 +485,10 @@ void VP9EncoderImpl::PopulateCodecSpecific(CodecSpecificInfo* codec_specific,
   vp9_info->inter_pic_predicted =
       (pkt.data.frame.flags & VPX_FRAME_IS_KEY) ? false : true;
   vp9_info->flexible_mode = codec_.codecSpecific.VP9.flexibleMode;
-  vp9_info->ss_data_available =
-      (pkt.data.frame.flags & VPX_FRAME_IS_KEY) ? true : false;
+  vp9_info->ss_data_available = ((pkt.data.frame.flags & VPX_FRAME_IS_KEY) &&
+                                 !codec_.codecSpecific.VP9.flexibleMode)
+                                    ? true
+                                    : false;
   if (pkt.data.frame.flags & VPX_FRAME_IS_KEY) {
     gof_idx_ = 0;
   }