Bug 1220885 - Add telemetry probe for rust mp4parse success. r=kinetik p=ally

This is a boolean to record the overall success rate of the new
demuxer path.

media/libstagefright/binding/MP4Metadata.cpp

@@ -9,6 +9,7 @@
 #include "media/stagefright/MetaData.h"
 #include "mozilla/Logging.h"
 #include "mozilla/Monitor.h"
+#include "mozilla/Telemetry.h"
 #include "mp4_demuxer/MoofParser.h"
 #include "mp4_demuxer/MP4Metadata.h"
 
@@ -142,7 +143,9 @@ MP4Metadata::GetNumberTracks(mozilla::TrackInfo::TrackType aType) const
 {
 #ifdef MOZ_RUST_MP4PARSE
   // Try in rust first.
-  try_rust(mSource);
+  bool rust_mp4parse_success = try_rust(mSource);
+  Telemetry::Accumulate(Telemetry::MEDIA_RUST_MP4PARSE_SUCCESS,
+                        rust_mp4parse_success);
 #endif
   size_t tracks = mPrivate->mMetadataExtractor->countTracks();
   uint32_t total = 0;

toolkit/components/telemetry/Histograms.json

@@ -6266,6 +6266,12 @@
     "n_buckets": "1000",
     "description": "The time (in milliseconds) that it took a 'reconfigure thread' request to go round trip."
   },
+  "MEDIA_RUST_MP4PARSE_SUCCESS": {
+    "expires_in_version": "50",
+    "kind": "boolean",
+    "description": "(Bug 1220885) Whether the rust mp4 demuxer successfully parsed a stream segment.",
+    "cpp_guard": "MOZ_RUST_MP4PARSE"
+  },
   "MEDIA_WMF_DECODE_ERROR": {
     "expires_in_version": "50",
     "kind": "enumerated",