message: [VP9 encoder] Set temporal id also on disabled spatial layers
  Cr-Commit-Position: refs/heads/master@{#30581}
diff: @@ -917,7 +917,10 @@ int VP9EncoderImpl::Encode(const VideoFrame& input_image,
  }
  }
  - for (int sl_idx = 0; sl_idx < num_active_spatial_layers_; ++sl_idx) {
  + // Need to set temporal layer id on ALL layers, even disabled ones.
  + // Otherwise libvpx might produce frames on a disabled layer:
  + // http://crbug.com/1051476
  + for (int sl_idx = 0; sl_idx < num_spatial_layers_; ++sl_idx) {
  layer_id.temporal_layer_id_per_spatial[sl_idx] = layer_id.temporal_layer_id;
  }
  