Use a TaskQueue for decoding in VideoStreamDecoderImpl.

Long term goal is to use the VideoStreamDecoder in the VideoReceiveStream so
that we can stop using legacy VideoCodingModule components and classes. This CL is
one of several in preparation for that.

Bug: webrtc:7408, webrtc:9378
Change-Id: Ifd7e4c3c7d38dbb7c4b0636aaad318c571a29158
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/164525
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30211}
diff --git a/video/BUILD.gn b/video/BUILD.gn
index 8cfbc94..daa3a57 100644
--- a/video/BUILD.gn
+++ b/video/BUILD.gn
@@ -564,11 +564,13 @@
       "video_receive_stream_unittest.cc",
       "video_send_stream_impl_unittest.cc",
       "video_send_stream_tests.cc",
+      "video_stream_decoder_impl_unittest.cc",
       "video_stream_encoder_unittest.cc",
     ]
     deps = [
       ":video",
       ":video_mocks",
+      ":video_stream_decoder_impl",
       ":video_stream_encoder_impl",
       "../api:create_frame_generator",
       "../api:fake_frame_decryptor",