Bug 1243234 - Update rust mp4parse telemetry reporting. r=kinetik

As of mp4parse 0.2.0 error codes are positive, as gecko telemetry
requires, so we no longer need to invert them. However, the return
code is still signed, so assert to catch future errors.

Also fix a bug in track comparison telemetry. We were only counting
tracks when parsing failed.

media/libstagefright/binding/MP4Metadata.cpp

@@ -142,10 +142,11 @@ MP4Metadata::GetNumberTracks(mozilla::TrackInfo::TrackType aType) const
   mRustState.reset(mp4parse_new());
   int32_t rust_mp4parse_success = try_rust(mRustState, mSource);
   Telemetry::Accumulate(Telemetry::MEDIA_RUST_MP4PARSE_SUCCESS,
-                        rust_mp4parse_success == 0);
-  if (rust_mp4parse_success < 0) {
+                        rust_mp4parse_success == MP4PARSE_OK);
+  if (rust_mp4parse_success != MP4PARSE_OK) {
+    MOZ_ASSERT(rust_mp4parse_success > 0);
     Telemetry::Accumulate(Telemetry::MEDIA_RUST_MP4PARSE_ERROR_CODE,
-                          -rust_mp4parse_success);
+                          rust_mp4parse_success);
   }
   uint32_t rust_tracks = mp4parse_get_track_count(mRustState.get());
   MOZ_LOG(sLog, LogLevel::Info, ("rust parser found %u tracks", rust_tracks));
@@ -179,7 +180,7 @@ MP4Metadata::GetNumberTracks(mozilla::TrackInfo::TrackType aType) const
 #ifdef MOZ_RUST_MP4PARSE
   uint32_t rust_total = 0;
   const char* rust_track_type = nullptr;
-  if (rust_mp4parse_success && rust_tracks > 0) {
+  if (rust_mp4parse_success == MP4PARSE_OK && rust_tracks > 0) {
     for (uint32_t i = 0; i < rust_tracks; ++i) {
       mp4parse_track_info track_info;
       int32_t r = mp4parse_get_track_info(mRustState.get(), i, &track_info);