If in simulcast case some streams are disabled (especially the first one), the key-frame requests might be ignorred by e.g. libvpx vp8 encoder wrapper. Before this CL SimulcastEncoderAdapter always passes single frame type in Encode() call. However, if underlying encoder used simulcast, it would've expected as many frame types as there are streams. Bug: none Change-Id: I7f56a6540b67273b7d3cf9fa86dc76015b92d271 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/165681 Reviewed-by: Evan Shrubsole <eshr@google.com> Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org> Cr-Commit-Position: refs/heads/master@{#30210}