[WebCodecs] Fix AV1 corruption test so dav1d actually fails

Test data was insufficiently corrupted, so dav1d just treats it as
partial data and expects more data to come. This change increases
the corruption of chunks.

R=eugene

Change-Id: Ia3eeea8faaf9dafe53a0a7fd3c148821fbc91f1d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7102887
Reviewed-by: Eugene Zemtsov <[email protected]>
Commit-Queue: Dale Curtis <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1538882}

Author: dalecurtis

webcodecs/videoDecoder-codec-specific-setup.js

@@ -189,8 +189,12 @@ function createVideoDecoder(t, callbacks) {
 
 function createCorruptChunk(index) {
   let bad_data = CHUNK_DATA[index];
-  for (var i = 0; i < bad_data.byteLength; i += 4)
+  // AV1 may require more extensive corruption to trigger decoding errors with
+  // some software decoders (e.g., dav1d).
+  let skip = CONFIG.codec.indexOf('av01') >= 0 ? 2 : 4;
+  for (var i = 0; i < bad_data.byteLength; i += skip) {
     bad_data[i] = 0xFF;
+  }
   return new EncodedVideoChunk(
       {type: 'delta', timestamp: index, data: bad_data});
 }