Add ID3v2 metadata parsing for Shaka packager detection.

This will help understand how frequently Shaka packager is used in
the wild. If usage is high enough we may add a UKM to figure out
whom it's most popular with.

BUG=927952

Change-Id: I144fa524fd2450e5fdd31f9baa24a9bc7b6bfbee
Reviewed-on: https://chromium-review.googlesource.com/c/1464921
Commit-Queue: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Matthew Wolenetz <wolenetz@chromium.org>
Auto-Submit: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636273}

media/formats/mp4/box_definitions.cc

@@ -4,14 +4,17 @@
 
 #include "media/formats/mp4/box_definitions.h"
 
+#include <algorithm>
 #include <memory>
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/logging.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/numerics/safe_math.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_piece.h"
 #include "build/build_config.h"
 #include "media/base/media_switches.h"
 #include "media/base/media_util.h"
@@ -1379,6 +1382,11 @@ bool Movie::Parse(BoxReader* reader) {
                       "require ISO BMFF moov to contain mvex to indicate that "
                       "Movie Fragments are to be expected.");
 
+  MetadataBox meta;
+  RCHECK(reader->MaybeReadChild(&meta));
+  base::UmaHistogramBoolean("Media.MSE.DetectedShakaPackagerInMp4",
+                            meta.used_shaka_packager);
+
   return reader->MaybeReadChildren(&pssh);
 }
 
@@ -1761,5 +1769,48 @@ SampleDependsOn IndependentAndDisposableSamples::sample_depends_on(
   return sample_depends_on_[i];
 }
 
+ID3v2Box::ID3v2Box() = default;
+ID3v2Box::ID3v2Box(const ID3v2Box& other) = default;
+ID3v2Box::~ID3v2Box() = default;
+FourCC ID3v2Box::BoxType() const {
+  return FOURCC_ID32;
+}
+
+bool ID3v2Box::Parse(BoxReader* reader) {
+  // This is reading the ID32 box without regard for what's in it -- there will
+  // likely be binary data in this vector. We don't care though since we're just
+  // going to scan the memory without caring about sentinel values like \0.
+  RCHECK(reader->ReadVec(&id3v2_data,
+                         std::min(static_cast<size_t>(128),
+                                  reader->buffer_size() - reader->pos())));
+  return true;
+}
+
+MetadataBox::MetadataBox() : used_shaka_packager(false) {}
+MetadataBox::MetadataBox(const MetadataBox& other) = default;
+MetadataBox::~MetadataBox() = default;
+FourCC MetadataBox::BoxType() const {
+  return FOURCC_META;
+}
+
+bool MetadataBox::Parse(BoxReader* reader) {
+  RCHECK(reader->ReadFullBoxHeader());
+
+  // This is an optional box, so generate no errors.
+  if (!reader->ScanChildren())
+    return true;
+
+  ID3v2Box id3v2;
+  if (!reader->ReadChild(&id3v2))
+    return true;
+
+  constexpr char kShakaPackager[] = "shaka-packager";
+  used_shaka_packager =
+      base::StringPiece(reinterpret_cast<char*>(id3v2.id3v2_data.data()),
+                        id3v2.id3v2_data.size())
+          .find(kShakaPackager) != base::StringPiece::npos;
+  return true;
+}
+
 }  // namespace mp4
 }  // namespace media

media/formats/mp4/box_definitions.h

@@ -549,6 +549,18 @@ struct MEDIA_EXPORT MovieFragment : Box {
   std::vector<ProtectionSystemSpecificHeader> pssh;
 };
 
+struct MEDIA_EXPORT ID3v2Box : Box {
+  DECLARE_BOX_METHODS(ID3v2Box);
+
+  // Up to a maximum of the first 128 bytes of the ID3v2 box.
+  std::vector<uint8_t> id3v2_data;
+};
+
+struct MEDIA_EXPORT MetadataBox : Box {
+  DECLARE_BOX_METHODS(MetadataBox);
+  bool used_shaka_packager;
+};
+
 #undef DECLARE_BOX
 
 }  // namespace mp4

media/formats/mp4/fourccs.h

@@ -60,6 +60,7 @@ enum FourCC {
   FOURCC_HVC1 = 0x68766331,
   FOURCC_HVCC = 0x68766343,
 #endif
+  FOURCC_ID32 = 0x49443332,
   FOURCC_IODS = 0x696f6473,
   FOURCC_MDAT = 0x6d646174,
   FOURCC_MDHD = 0x6d646864,

media/formats/mp4/mp4_stream_parser_unittest.cc

@@ -16,6 +16,7 @@
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
+#include "base/test/metrics/histogram_tester.h"
 #include "base/test/scoped_feature_list.h"
 #include "base/time/time.h"
 #include "media/base/audio_decoder_config.h"
@@ -258,6 +259,35 @@ TEST_F(MP4StreamParserTest, UnalignedAppend) {
   ParseMP4File("bear-1280x720-av_frag.mp4", 512);
 }
 
+constexpr char kShakaPackagerUMA[] = "Media.MSE.DetectedShakaPackagerInMp4";
+
+TEST_F(MP4StreamParserTest, DidNotUseShakaPackager) {
+  // Encrypted files have non-zero duration and are treated as recorded streams.
+  auto params = GetDefaultInitParametersExpectations();
+  params.duration = base::TimeDelta::FromMicroseconds(2736066);
+  params.liveness = DemuxerStream::LIVENESS_RECORDED;
+  params.detected_audio_track_count = 0;
+  InitializeParserWithInitParametersExpectations(params);
+
+  base::HistogramTester tester;
+
+  // Test file has ID32 box, but no shaka player metadata.
+  ParseMP4File("bear-640x360-v_frag-cenc-senc-no-saiz-saio.mp4", 512);
+  tester.ExpectUniqueSample(kShakaPackagerUMA, 0, 1);
+}
+
+TEST_F(MP4StreamParserTest, UsedShakaPackager) {
+  auto params = GetDefaultInitParametersExpectations();
+  params.duration = base::TimeDelta::FromMicroseconds(2736000);
+  params.liveness = DemuxerStream::LIVENESS_RECORDED;
+  params.detected_audio_track_count = 0;
+  InitializeParserWithInitParametersExpectations(params);
+
+  base::HistogramTester tester;
+  ParseMP4File("bear-320x240-v_frag-vp9.mp4", 512);
+  tester.ExpectUniqueSample(kShakaPackagerUMA, 1, 1);
+}
+
 TEST_F(MP4StreamParserTest, BytewiseAppend) {
   // Ensure no incremental errors occur when parsing
   InitializeParser();

tools/metrics/histograms/histograms.xml

@@ -49646,6 +49646,17 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="Media.MSE.DetectedShakaPackagerInMp4" enum="BooleanDetected"
+    expires_after="2019-12-01">
+  <owner>dalecurtis@chromium.org</owner>
+  <owner>media-dev@chromium.org</owner>
+  <summary>
+    Tracks if ShakaPackager metadata was detected in the MP4 'moov' atom during
+    MSE based media playback. Recorded for every 'moov' atom, which is expected
+    once per asset. Multiple assets may be played within the same MSE session.
+  </summary>
+</histogram>
+
 <histogram name="Media.MSE.DetectedTrackCount.Audio">
   <owner>wolenetz@chromium.org</owner>
   <summary>