Fix nullptr issue in Dav1dVideoDecoder when allocation OOMs.

R=tguilbert

Fixed: 1084886
Change-Id: I544bef88c9b727b4fa1e6f0672fb396200a1b957
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2209904
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Thomas Guilbert <tguilbert@chromium.org>
Auto-Submit: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Thomas Guilbert <tguilbert@chromium.org>
Cr-Commit-Position: refs/heads/master@{#770766}

media/filters/dav1d_video_decoder.cc

@@ -427,6 +427,8 @@ scoped_refptr<VideoFrame> Dav1dVideoDecoder::BindImageToVideoFrame(
       config_.natural_size(), pic->stride[0], uv_plane_stride, uv_plane_stride,
       static_cast<uint8_t*>(pic->data[0]), u_plane, v_plane,
       base::TimeDelta::FromMicroseconds(pic->m.timestamp));
+  if (!frame)
+    return nullptr;
 
   // Each frame needs a ref on the fake UV data to keep it alive until done.
   if (needs_fake_uv_planes) {