Bug 1519919 - Add gtest for the MoofParser handling moovs with multiple tracks followed by moofs with only 1 track. r=jya

Add a test file that has a moov with two tracks, but which has had the track
fragment headers removed for the second track. Created from bipbop.mp4 via:
`mp4box bipbop.mp4 -dash 5000 -subsegs-per-sidx -1 -segment-name
$Segment=bipbop_$$Init=bipbop_init$`, concatenating the init and segments
back into an mp4, then overwriting track 2's trafs with frees.

While we shouldn't expect people to create files such as this, it does simulate
if the MoofParser is fed metadata for multiple tracks, but then is not fed
fragments for one of these tracks. This appears to have been the case when bug
1519617 broke soundcloud.com, so we should have test coverage for this.

Depends on D17070

Differential Revision: https://phabricator.services.mozilla.com/D17071

--HG--
extra : moz-landing-system : lando

dom/media/gtest/mp4_demuxer/TestParser.cpp

@@ -237,6 +237,8 @@ static const TestFileData testFiles[] = {
     {"test_case_1519617-cenc-init-with-track_id-0.mp4", true, 1, true, 0, 1272,
      530, 0, -1, false, 0, false, false,
      0},  // Uses bad track id 0 and has a sinf but no pssh
+    {"test_case_1519617-track2-trafs-removed.mp4", true, 1, true, 10032000, 400,
+     300, 1, 10032000, false, 0, true, true, 2},
     {"test_case_1519617-video-has-track_id-0.mp4", true, 1, true, 10032000, 400,
      300, 1, 10032000, false, 0, true, true, 2},  // Uses bad track id 0
 };
@@ -592,6 +594,43 @@ TEST(MoofParser, test_case_track_id_0_reads_crypto_metadata) {
       << "Sample description should be marked as encrypted!";
 }
 
+// The MoofParser may be asked to parse metadata for multiple tracks, but then
+// be presented with fragments/moofs that contain data for only a subset of
+// those tracks. I.e. metadata contains information for tracks with ids 1 and 2,
+// but then the moof parser only receives moofs with data for track id 1. We
+// should parse such fragmented media. In this test the metadata contains info
+// for track ids 1 and 2, but track 2's track fragment headers (traf) have been
+// over written with free space boxes (free).
+TEST(MoofParser, test_case_moofs_missing_trafs) {
+  const char* noTrafsForTrack2MoofsFileName =
+      "test_case_1519617-track2-trafs-removed.mp4";
+  nsTArray<uint8_t> buffer = ReadTestFile(noTrafsForTrack2MoofsFileName);
+
+  ASSERT_FALSE(buffer.IsEmpty());
+  RefPtr<ByteStream> stream =
+      new TestStream(buffer.Elements(), buffer.Length());
+
+  // Create parser that will read metadata from all tracks.
+  MoofParser parser(stream, 0, false, true);
+
+  // Explicitly don't call parser.Metadata() so that the parser itself will
+  // read the metadata as if we're in a fragmented case. Otherwise we won't
+  // read the trak data.
+
+  const MediaByteRangeSet byteRanges(
+      MediaByteRange(0, int64_t(buffer.Length())));
+  EXPECT_TRUE(parser.RebuildFragmentedIndex(byteRanges))
+      << "MoofParser should find a valid moof, there's 2 in the file!";
+
+  // Verify we've found 2 moofs and that the parser was able to parse them.
+  const size_t numMoofs = 2;
+  EXPECT_EQ(numMoofs, parser.Moofs().Length())
+      << "File has 2 moofs, we should have read both";
+  for (size_t i = 0; i < parser.Moofs().Length(); i++) {
+    EXPECT_TRUE(parser.Moofs()[i].IsValid()) << "All moofs should be valid";
+  }
+}
+
 // This test was disabled by Bug 1224019 for producing way too much output.
 // This test no longer produces such output, as we've moved away from
 // stagefright, but it does take a long time to run. I can be useful to enable

dom/media/gtest/mp4_demuxer/moz.build

@@ -43,6 +43,7 @@ TEST_HARNESS_FILES.gtest += [
     'test_case_1395244.mp4',
     'test_case_1410565.mp4',
     'test_case_1519617-cenc-init-with-track_id-0.mp4',
+    'test_case_1519617-track2-trafs-removed.mp4',
     'test_case_1519617-video-has-track_id-0.mp4',
 ]