Fix obsolete settings in VideoEngine for VP9 screenshare

Bug: webrtc:10257
Change-Id: I092af5ea2d3700bd9bfe60438918bbfcd8d10dbf
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/128771
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27241}
diff --git a/media/engine/webrtc_video_engine.cc b/media/engine/webrtc_video_engine.cc
index 36473cb..a591ee3 100644
--- a/media/engine/webrtc_video_engine.cc
+++ b/media/engine/webrtc_video_engine.cc
@@ -389,8 +389,9 @@
       // Limit inter-layer prediction to key pictures.
       vp9_settings.interLayerPred = webrtc::InterLayerPredMode::kOnKeyPic;
     } else {
-      // 3 spatial layers vp9 screenshare needs flexible mode.
-      vp9_settings.flexibleMode = vp9_settings.numberOfSpatialLayers > 2;
+      // Multiple spatial layers vp9 screenshare needs flexible mode.
+      vp9_settings.flexibleMode = vp9_settings.numberOfSpatialLayers > 1;
+      vp9_settings.interLayerPred = webrtc::InterLayerPredMode::kOn;
     }
     return new rtc::RefCountedObject<
         webrtc::VideoEncoderConfig::Vp9EncoderSpecificSettings>(vp9_settings);