[Fuchsia] Enable MPEG2-TS MediaSource parser

This will allow to play video/mp2t streams on Fuchsia.

Bug: b/139838994, 999736
Change-Id: Icd19b8e223af8ff2e6edb465f2f226b3130c2209
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1769349Reviewed-by: Matthew Wolenetz <wolenetz@chromium.org>
Commit-Queue: Matthew Wolenetz <wolenetz@chromium.org>
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692307}

media/media_options.gni

@@ -61,7 +61,7 @@ declare_args() {
   enable_mpeg_h_audio_demuxing = proprietary_codecs && is_chromecast
 
   enable_mse_mpeg2ts_stream_parser =
-      proprietary_codecs && (is_chromecast || use_fuzzing_engine)
+      proprietary_codecs && (is_chromecast || is_fuchsia || use_fuzzing_engine)
 
   # Enable parsing for the 'cbcs' encryption scheme added by MPEG Common
   # Encryption 3rd Edition (ISO/IEC 23001-7), published 02/15/2016.