Fix missing trailing slash.

TBR=eugene@chromium.org

Bug: 1129740, 1122955
Change-Id: I2b70502587c1c889388113f58c9987e737a19d0f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2418851Reviewed-by: Ben Mason <benmason@chromium.org>
Commit-Queue: Ben Mason <benmason@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808395}

media/BUILD.gn

@@ -164,7 +164,7 @@ test("media_unittests") {
 
   data = [
     "test/data/",
-    "formats/mp4/h264_annex_b_fuzz_corpus",
+    "formats/mp4/h264_annex_b_fuzz_corpus/",
   ]
 
   data_deps = [ "//testing/buildbot/filters:media_unittests_filters" ]