Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1161 insertions, 0 deletions

diff --git a/dom/media/eme/MediaKeySystemAccess.cpp b/dom/media/eme/MediaKeySystemAccess.cpp
new file mode 100644
index 0000000000..b58ff76424
--- /dev/null
+++ b/dom/media/eme/MediaKeySystemAccess.cpp
@@ -0,0 +1,1161 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/MediaKeySystemAccess.h"
+
+#include <functional>
+
+#include "DecoderDoctorDiagnostics.h"
+#include "DecoderTraits.h"
+#include "KeySystemConfig.h"
+#include "MP4Decoder.h"
+#include "MediaContainerType.h"
+#include "WebMDecoder.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/EMEUtils.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/Services.h"
+#include "mozilla/StaticPrefs_media.h"
+#include "mozilla/dom/KeySystemNames.h"
+#include "mozilla/dom/MediaKeySession.h"
+#include "mozilla/dom/MediaKeySystemAccessBinding.h"
+#include "mozilla/dom/MediaKeySystemAccessManager.h"
+#include "mozilla/dom/MediaSource.h"
+#include "nsDOMString.h"
+#include "nsIObserverService.h"
+#include "nsMimeTypes.h"
+#include "nsReadableUtils.h"
+#include "nsServiceManagerUtils.h"
+#include "nsUnicharUtils.h"
+
+#ifdef XP_WIN
+#  include "WMFDecoderModule.h"
+#endif
+#ifdef MOZ_WIDGET_ANDROID
+#  include "mozilla/java/MediaDrmProxyWrappers.h"
+#endif
+
+namespace mozilla::dom {
+
+#define LOG(msg, ...) \
+  EME_LOG("MediaKeySystemAccess::%s " msg, __func__, ##__VA_ARGS__)
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(MediaKeySystemAccess, mParent)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(MediaKeySystemAccess)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(MediaKeySystemAccess)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MediaKeySystemAccess)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+static nsCString ToCString(const MediaKeySystemConfiguration& aConfig);
+
+MediaKeySystemAccess::MediaKeySystemAccess(
+    nsPIDOMWindowInner* aParent, const nsAString& aKeySystem,
+    const MediaKeySystemConfiguration& aConfig)
+    : mParent(aParent), mKeySystem(aKeySystem), mConfig(aConfig) {
+  LOG("Created MediaKeySystemAccess for keysystem=%s config=%s",
+      NS_ConvertUTF16toUTF8(mKeySystem).get(),
+      mozilla::dom::ToCString(mConfig).get());
+}
+
+MediaKeySystemAccess::~MediaKeySystemAccess() = default;
+
+JSObject* MediaKeySystemAccess::WrapObject(JSContext* aCx,
+                                           JS::Handle<JSObject*> aGivenProto) {
+  return MediaKeySystemAccess_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+nsPIDOMWindowInner* MediaKeySystemAccess::GetParentObject() const {
+  return mParent;
+}
+
+void MediaKeySystemAccess::GetKeySystem(nsString& aOutKeySystem) const {
+  aOutKeySystem.Assign(mKeySystem);
+}
+
+void MediaKeySystemAccess::GetConfiguration(
+    MediaKeySystemConfiguration& aConfig) {
+  aConfig = mConfig;
+}
+
+already_AddRefed<Promise> MediaKeySystemAccess::CreateMediaKeys(
+    ErrorResult& aRv) {
+  RefPtr<MediaKeys> keys(new MediaKeys(mParent, mKeySystem, mConfig));
+  return keys->Init(aRv);
+}
+
+enum class SecureLevel {
+  Software,
+  Hardware,
+};
+
+static MediaKeySystemStatus EnsureCDMInstalled(const nsAString& aKeySystem,
+                                               const SecureLevel aSecure,
+                                               nsACString& aOutMessage) {
+  if (aSecure == SecureLevel::Software &&
+      !KeySystemConfig::Supports(aKeySystem)) {
+    aOutMessage = "CDM is not installed"_ns;
+    return MediaKeySystemStatus::Cdm_not_installed;
+  }
+
+#ifdef MOZ_WMF_CDM
+  if (aSecure == SecureLevel::Hardware) {
+    // Ensure we check the hardware key system name.
+    nsAutoString hardwareKeySystem;
+    if (IsWidevineKeySystem(aKeySystem) ||
+        IsWidevineExperimentKeySystemAndSupported(aKeySystem)) {
+      hardwareKeySystem =
+          NS_ConvertUTF8toUTF16(kWidevineExperimentKeySystemName);
+    } else if (IsPlayReadyKeySystemAndSupported(aKeySystem)) {
+      hardwareKeySystem = NS_ConvertUTF8toUTF16(kPlayReadyKeySystemHardware);
+    } else {
+      MOZ_ASSERT_UNREACHABLE("Not supported key system for HWDRM!");
+    }
+    if (!KeySystemConfig::Supports(hardwareKeySystem)) {
+      aOutMessage = "CDM is not installed"_ns;
+      return MediaKeySystemStatus::Cdm_not_installed;
+    }
+  }
+#endif
+
+  return MediaKeySystemStatus::Available;
+}
+
+/* static */
+MediaKeySystemStatus MediaKeySystemAccess::GetKeySystemStatus(
+    const MediaKeySystemAccessRequest& aRequest, nsACString& aOutMessage) {
+  const nsString& keySystem = aRequest.mKeySystem;
+
+  MOZ_ASSERT(StaticPrefs::media_eme_enabled() ||
+             IsClearkeyKeySystem(keySystem));
+
+  LOG("checking if CDM is installed or disabled for %s",
+      NS_ConvertUTF16toUTF8(keySystem).get());
+  if (IsClearkeyKeySystem(keySystem)) {
+    return EnsureCDMInstalled(keySystem, SecureLevel::Software, aOutMessage);
+  }
+
+  // This is used to determine if we need to download Widevine L1.
+  bool shouldCheckL1Installation = false;
+#ifdef MOZ_WMF_CDM
+  if (StaticPrefs::media_eme_widevine_experiment_enabled()) {
+    shouldCheckL1Installation =
+        CheckIfHarewareDRMConfigExists(aRequest.mConfigs) ||
+        IsWidevineExperimentKeySystemAndSupported(keySystem);
+  }
+#endif
+
+  // Check Widevine L3
+  if (IsWidevineKeySystem(keySystem) && !shouldCheckL1Installation) {
+    if (Preferences::GetBool("media.gmp-widevinecdm.visible", false)) {
+      if (!Preferences::GetBool("media.gmp-widevinecdm.enabled", false)) {
+        aOutMessage = "Widevine EME disabled"_ns;
+        return MediaKeySystemStatus::Cdm_disabled;
+      }
+      return EnsureCDMInstalled(keySystem, SecureLevel::Software, aOutMessage);
+#ifdef MOZ_WIDGET_ANDROID
+    } else if (Preferences::GetBool("media.mediadrm-widevinecdm.visible",
+                                    false)) {
+      bool supported =
+          mozilla::java::MediaDrmProxy::IsSchemeSupported(keySystem);
+      if (!supported) {
+        aOutMessage = nsLiteralCString(
+            "KeySystem or Minimum API level not met for Widevine EME");
+        return MediaKeySystemStatus::Cdm_not_supported;
+      }
+      return MediaKeySystemStatus::Available;
+#endif
+    }
+  }
+
+#ifdef MOZ_WMF_CDM
+  // Check PlayReady, which is a built-in CDM on most Windows versions.
+  if (IsPlayReadyKeySystemAndSupported(keySystem) &&
+      KeySystemConfig::Supports(keySystem)) {
+    return MediaKeySystemStatus::Available;
+  }
+
+  // Check Widevine L1. This can be a request for experimental key systems, or
+  // for a normal key system with hardware robustness.
+  if ((IsWidevineExperimentKeySystemAndSupported(keySystem) ||
+       IsWidevineKeySystem(keySystem)) &&
+      shouldCheckL1Installation) {
+    // TODO : if L3 hasn't been installed as well, should we fallback to install
+    // L3?
+    if (!Preferences::GetBool("media.gmp-widevinecdm-l1.enabled", false)) {
+      aOutMessage = "Widevine L1 EME disabled"_ns;
+      return MediaKeySystemStatus::Cdm_disabled;
+    }
+    return EnsureCDMInstalled(keySystem, SecureLevel::Hardware, aOutMessage);
+  }
+#endif
+
+  return MediaKeySystemStatus::Cdm_not_supported;
+}
+
+static KeySystemConfig::EMECodecString ToEMEAPICodecString(
+    const nsString& aCodec) {
+  if (IsAACCodecString(aCodec)) {
+    return KeySystemConfig::EME_CODEC_AAC;
+  }
+  if (aCodec.EqualsLiteral("opus")) {
+    return KeySystemConfig::EME_CODEC_OPUS;
+  }
+  if (aCodec.EqualsLiteral("vorbis")) {
+    return KeySystemConfig::EME_CODEC_VORBIS;
+  }
+  if (aCodec.EqualsLiteral("flac")) {
+    return KeySystemConfig::EME_CODEC_FLAC;
+  }
+  if (IsH264CodecString(aCodec)) {
+    return KeySystemConfig::EME_CODEC_H264;
+  }
+  if (IsVP8CodecString(aCodec)) {
+    return KeySystemConfig::EME_CODEC_VP8;
+  }
+  if (IsVP9CodecString(aCodec)) {
+    return KeySystemConfig::EME_CODEC_VP9;
+  }
+#ifdef MOZ_WMF
+  if (IsH265CodecString(aCodec)) {
+    return KeySystemConfig::EME_CODEC_HEVC;
+  }
+#endif
+  return ""_ns;
+}
+
+static nsTArray<KeySystemConfig> GetSupportedKeySystems() {
+  nsTArray<KeySystemConfig> keySystemConfigs;
+
+  const nsTArray<nsString> keySystemNames{
+      NS_ConvertUTF8toUTF16(kClearKeyKeySystemName),
+      NS_ConvertUTF8toUTF16(kWidevineKeySystemName),
+#ifdef MOZ_WMF_CDM
+      NS_ConvertUTF8toUTF16(kPlayReadyKeySystemName),
+      NS_ConvertUTF8toUTF16(kPlayReadyKeySystemHardware),
+      NS_ConvertUTF8toUTF16(kPlayReadyHardwareClearLeadKeySystemName),
+      NS_ConvertUTF8toUTF16(kWidevineExperimentKeySystemName),
+      NS_ConvertUTF8toUTF16(kWidevineExperiment2KeySystemName),
+#endif
+  };
+  for (const auto& name : keySystemNames) {
+    Unused << KeySystemConfig::CreateKeySystemConfigs(name, keySystemConfigs);
+  }
+  return keySystemConfigs;
+}
+
+static bool GetKeySystemConfigs(
+    const nsAString& aKeySystem,
+    nsTArray<KeySystemConfig>& aOutKeySystemConfig) {
+  bool foundConfigs = false;
+  for (auto& config : GetSupportedKeySystems()) {
+    if (config.IsSameKeySystem(aKeySystem)) {
+      aOutKeySystemConfig.AppendElement(std::move(config));
+      foundConfigs = true;
+    }
+  }
+  return foundConfigs;
+}
+
+/* static */
+bool MediaKeySystemAccess::KeySystemSupportsInitDataType(
+    const nsAString& aKeySystem, const nsAString& aInitDataType) {
+  nsTArray<KeySystemConfig> implementations;
+  GetKeySystemConfigs(aKeySystem, implementations);
+  bool containInitType = false;
+  for (const auto& config : implementations) {
+    if (config.mInitDataTypes.Contains(aInitDataType)) {
+      containInitType = true;
+      break;
+    }
+  }
+  return containInitType;
+}
+
+enum CodecType { Audio, Video, Invalid };
+
+static bool CanDecryptAndDecode(
+    const nsString& aKeySystem, const nsString& aContentType,
+    CodecType aCodecType,
+    const KeySystemConfig::ContainerSupport& aContainerSupport,
+    const nsTArray<KeySystemConfig::EMECodecString>& aCodecs,
+    DecoderDoctorDiagnostics* aDiagnostics) {
+  MOZ_ASSERT(aCodecType != Invalid);
+  for (const KeySystemConfig::EMECodecString& codec : aCodecs) {
+    MOZ_ASSERT(!codec.IsEmpty());
+
+    if (aContainerSupport.DecryptsAndDecodes(codec)) {
+      // GMP can decrypt-and-decode this codec.
+      continue;
+    }
+
+    if (aContainerSupport.Decrypts(codec)) {
+      IgnoredErrorResult rv;
+      MediaSource::IsTypeSupported(aContentType, aDiagnostics, rv);
+      if (!rv.Failed()) {
+        // GMP can decrypt and is allowed to return compressed samples to
+        // Gecko to decode, and Gecko has a decoder.
+        continue;
+      }
+    }
+
+    // Neither the GMP nor Gecko can both decrypt and decode. We don't
+    // support this codec.
+
+#if defined(XP_WIN)
+    // Widevine CDM doesn't include an AAC decoder. So if WMF can't
+    // decode AAC, and a codec wasn't specified, be conservative
+    // and reject the MediaKeys request, since we assume Widevine
+    // will be used with AAC.
+    if (codec == KeySystemConfig::EME_CODEC_AAC &&
+        IsWidevineKeySystem(aKeySystem) &&
+        !WMFDecoderModule::CanCreateMFTDecoder(WMFStreamType::AAC)) {
+      if (aDiagnostics) {
+        aDiagnostics->SetKeySystemIssue(
+            DecoderDoctorDiagnostics::eWidevineWithNoWMF);
+      }
+    }
+#endif
+    return false;
+  }
+  return true;
+}
+
+// Returns if an encryption scheme is supported per:
+// https://github.com/WICG/encrypted-media-encryption-scheme/blob/master/explainer.md
+// To be supported the scheme should be one of:
+// - null
+// - missing (which will result in the nsString being set to void and thus null)
+// - one of the schemes supported by the CDM
+// If the pref to enable this behavior is not set, then the value should be
+// empty/null, as the dict member will not be exposed. In this case we will
+// always report support as we would before this feature was implemented.
+static bool SupportsEncryptionScheme(
+    const nsString& aEncryptionScheme,
+    const nsTArray<nsString>& aSupportedEncryptionSchemes) {
+  MOZ_ASSERT(
+      DOMStringIsNull(aEncryptionScheme) ||
+          StaticPrefs::media_eme_encrypted_media_encryption_scheme_enabled(),
+      "Encryption scheme checking support must be preffed on for "
+      "encryptionScheme to be a non-null string");
+  if (DOMStringIsNull(aEncryptionScheme)) {
+    // "A missing or null value indicates that any encryption scheme is
+    // acceptable."
+    return true;
+  }
+  return aSupportedEncryptionSchemes.Contains(aEncryptionScheme);
+}
+
+static bool ToSessionType(const nsAString& aSessionType,
+                          MediaKeySessionType& aOutType) {
+  if (aSessionType.Equals(ToString(MediaKeySessionType::Temporary))) {
+    aOutType = MediaKeySessionType::Temporary;
+    return true;
+  }
+  if (aSessionType.Equals(ToString(MediaKeySessionType::Persistent_license))) {
+    aOutType = MediaKeySessionType::Persistent_license;
+    return true;
+  }
+  return false;
+}
+
+// 5.1.1 Is persistent session type?
+static bool IsPersistentSessionType(MediaKeySessionType aSessionType) {
+  return aSessionType == MediaKeySessionType::Persistent_license;
+}
+
+static bool ContainsSessionType(
+    const nsTArray<KeySystemConfig::SessionType>& aTypes,
+    const MediaKeySessionType& aSessionType) {
+  return (aSessionType == MediaKeySessionType::Persistent_license &&
+          aTypes.Contains(KeySystemConfig::SessionType::PersistentLicense)) ||
+         (aSessionType == MediaKeySessionType::Temporary &&
+          aTypes.Contains(KeySystemConfig::SessionType::Temporary));
+}
+
+CodecType GetMajorType(const MediaMIMEType& aMIMEType) {
+  if (aMIMEType.HasAudioMajorType()) {
+    return Audio;
+  }
+  if (aMIMEType.HasVideoMajorType()) {
+    return Video;
+  }
+  return Invalid;
+}
+
+static CodecType GetCodecType(const KeySystemConfig::EMECodecString& aCodec) {
+  if (aCodec.Equals(KeySystemConfig::EME_CODEC_AAC) ||
+      aCodec.Equals(KeySystemConfig::EME_CODEC_OPUS) ||
+      aCodec.Equals(KeySystemConfig::EME_CODEC_VORBIS) ||
+      aCodec.Equals(KeySystemConfig::EME_CODEC_FLAC)) {
+    return Audio;
+  }
+  if (aCodec.Equals(KeySystemConfig::EME_CODEC_H264) ||
+      aCodec.Equals(KeySystemConfig::EME_CODEC_VP8) ||
+      aCodec.Equals(KeySystemConfig::EME_CODEC_VP9) ||
+      aCodec.Equals(KeySystemConfig::EME_CODEC_HEVC)) {
+    return Video;
+  }
+  return Invalid;
+}
+
+static bool AllCodecsOfType(
+    const nsTArray<KeySystemConfig::EMECodecString>& aCodecs,
+    const CodecType aCodecType) {
+  for (const KeySystemConfig::EMECodecString& codec : aCodecs) {
+    if (GetCodecType(codec) != aCodecType) {
+      return false;
+    }
+  }
+  return true;
+}
+
+static bool IsParameterUnrecognized(const nsAString& aContentType) {
+  nsAutoString contentType(aContentType);
+  contentType.StripWhitespace();
+
+  nsTArray<nsString> params;
+  nsAString::const_iterator start, end, semicolon, equalSign;
+  contentType.BeginReading(start);
+  contentType.EndReading(end);
+  semicolon = start;
+  // Find any substring between ';' & '='.
+  while (semicolon != end) {
+    if (FindCharInReadable(';', semicolon, end)) {
+      equalSign = ++semicolon;
+      if (FindCharInReadable('=', equalSign, end)) {
+        params.AppendElement(Substring(semicolon, equalSign));
+        semicolon = equalSign;
+      }
+    }
+  }
+
+  for (auto param : params) {
+    if (!param.LowerCaseEqualsLiteral("codecs") &&
+        !param.LowerCaseEqualsLiteral("profiles")) {
+      return true;
+    }
+  }
+  return false;
+}
+
+// 3.1.1.3 Get Supported Capabilities for Audio/Video Type
+static Sequence<MediaKeySystemMediaCapability> GetSupportedCapabilities(
+    const CodecType aCodecType,
+    const nsTArray<MediaKeySystemMediaCapability>& aRequestedCapabilities,
+    const MediaKeySystemConfiguration& aPartialConfig,
+    const KeySystemConfig& aKeySystem, DecoderDoctorDiagnostics* aDiagnostics,
+    const std::function<void(const char*)>& aDeprecationLogFn) {
+  // Let local accumulated configuration be a local copy of partial
+  // configuration. (Note: It's not necessary for us to maintain a local copy,
+  // as we don't need to test whether capabilites from previous calls to this
+  // algorithm work with the capabilities currently being considered in this
+  // call. )
+
+  // Let supported media capabilities be an empty sequence of
+  // MediaKeySystemMediaCapability dictionaries.
+  Sequence<MediaKeySystemMediaCapability> supportedCapabilities;
+
+  // For each requested media capability in requested media capabilities:
+  for (const MediaKeySystemMediaCapability& capabilities :
+       aRequestedCapabilities) {
+    // Let content type be requested media capability's contentType member.
+    const nsString& contentTypeString = capabilities.mContentType;
+    // Let robustness be requested media capability's robustness member.
+    const nsString& robustness = capabilities.mRobustness;
+    // Optional encryption scheme extension, see
+    // https://github.com/WICG/encrypted-media-encryption-scheme/blob/master/explainer.md
+    // This will only be exposed to JS if
+    // media.eme.encrypted-media-encryption-scheme.enabled is preffed on.
+    const nsString encryptionScheme = capabilities.mEncryptionScheme;
+    // If content type is the empty string, return null.
+    if (contentTypeString.IsEmpty()) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') "
+          "MediaKeySystemMediaCapability('%s','%s','%s') rejected; "
+          "audio or video capability has empty contentType.",
+          NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+          NS_ConvertUTF16toUTF8(contentTypeString).get(),
+          NS_ConvertUTF16toUTF8(robustness).get(),
+          NS_ConvertUTF16toUTF8(encryptionScheme).get());
+      return Sequence<MediaKeySystemMediaCapability>();
+    }
+    // If content type is an invalid or unrecognized MIME type, continue
+    // to the next iteration.
+    Maybe<MediaContainerType> maybeContainerType =
+        MakeMediaContainerType(contentTypeString);
+    if (!maybeContainerType) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') "
+          "MediaKeySystemMediaCapability('%s','%s','%s') unsupported; "
+          "failed to parse contentTypeString as MIME type.",
+          NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+          NS_ConvertUTF16toUTF8(contentTypeString).get(),
+          NS_ConvertUTF16toUTF8(robustness).get(),
+          NS_ConvertUTF16toUTF8(encryptionScheme).get());
+      continue;
+    }
+    const MediaContainerType& containerType = *maybeContainerType;
+    bool invalid = false;
+    nsTArray<KeySystemConfig::EMECodecString> codecs;
+    for (const auto& codecString :
+         containerType.ExtendedType().Codecs().Range()) {
+      KeySystemConfig::EMECodecString emeCodec =
+          ToEMEAPICodecString(nsString(codecString));
+      if (emeCodec.IsEmpty()) {
+        invalid = true;
+        EME_LOG(
+            "MediaKeySystemConfiguration (label='%s') "
+            "MediaKeySystemMediaCapability('%s','%s','%s') unsupported; "
+            "'%s' is an invalid codec string.",
+            NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+            NS_ConvertUTF16toUTF8(contentTypeString).get(),
+            NS_ConvertUTF16toUTF8(robustness).get(),
+            NS_ConvertUTF16toUTF8(encryptionScheme).get(),
+            NS_ConvertUTF16toUTF8(codecString).get());
+        break;
+      }
+      codecs.AppendElement(emeCodec);
+    }
+    if (invalid) {
+      continue;
+    }
+
+    // If the user agent does not support container, continue to the next
+    // iteration. The case-sensitivity of string comparisons is determined by
+    // the appropriate RFC. (Note: Per RFC 6838 [RFC6838], "Both top-level type
+    // and subtype names are case-insensitive."'. We're using
+    // nsContentTypeParser and that is case-insensitive and converts all its
+    // parameter outputs to lower case.)
+    const bool supportedInMP4 =
+        MP4Decoder::IsSupportedType(containerType, aDiagnostics);
+    if (supportedInMP4 && !aKeySystem.mMP4.IsSupported()) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') "
+          "MediaKeySystemMediaCapability('%s','%s','%s') unsupported; "
+          "MP4 requested but unsupported.",
+          NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+          NS_ConvertUTF16toUTF8(contentTypeString).get(),
+          NS_ConvertUTF16toUTF8(robustness).get(),
+          NS_ConvertUTF16toUTF8(encryptionScheme).get());
+      continue;
+    }
+    const bool isWebM = WebMDecoder::IsSupportedType(containerType);
+    if (isWebM && !aKeySystem.mWebM.IsSupported()) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') "
+          "MediaKeySystemMediaCapability('%s','%s,'%s') unsupported; "
+          "WebM requested but unsupported.",
+          NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+          NS_ConvertUTF16toUTF8(contentTypeString).get(),
+          NS_ConvertUTF16toUTF8(robustness).get(),
+          NS_ConvertUTF16toUTF8(encryptionScheme).get());
+      continue;
+    }
+    if (!supportedInMP4 && !isWebM) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') "
+          "MediaKeySystemMediaCapability('%s','%s','%s') unsupported; "
+          "Unsupported or unrecognized container requested.",
+          NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+          NS_ConvertUTF16toUTF8(contentTypeString).get(),
+          NS_ConvertUTF16toUTF8(robustness).get(),
+          NS_ConvertUTF16toUTF8(encryptionScheme).get());
+      continue;
+    }
+
+    // Let parameters be the RFC 6381[RFC6381] parameters, if any, specified by
+    // content type.
+    // If the user agent does not recognize one or more parameters, continue to
+    // the next iteration.
+    if (IsParameterUnrecognized(contentTypeString)) {
+      continue;
+    }
+
+    // Let media types be the set of codecs and codec constraints specified by
+    // parameters. The case-sensitivity of string comparisons is determined by
+    // the appropriate RFC or other specification.
+    // (Note: codecs array is 'parameter').
+
+    // If media types is empty:
+    if (codecs.IsEmpty()) {
+      // Log deprecation warning to encourage authors to not do this!
+      aDeprecationLogFn("MediaEMENoCodecsDeprecatedWarning");
+      // TODO: Remove this once we're sure it doesn't break the web.
+      // If container normatively implies a specific set of codecs and codec
+      // constraints: Let parameters be that set.
+      if (supportedInMP4) {
+        if (aCodecType == Audio) {
+          codecs.AppendElement(KeySystemConfig::EME_CODEC_AAC);
+        } else if (aCodecType == Video) {
+          codecs.AppendElement(KeySystemConfig::EME_CODEC_H264);
+        }
+      } else if (isWebM) {
+        if (aCodecType == Audio) {
+          codecs.AppendElement(KeySystemConfig::EME_CODEC_VORBIS);
+        } else if (aCodecType == Video) {
+          codecs.AppendElement(KeySystemConfig::EME_CODEC_VP8);
+        }
+      }
+      // Otherwise: Continue to the next iteration.
+      // (Note: all containers we support have implied codecs, so don't continue
+      // here.)
+    }
+
+    // If container type is not strictly a audio/video type, continue to the
+    // next iteration.
+    const auto majorType = GetMajorType(containerType.Type());
+    if (majorType == Invalid) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') "
+          "MediaKeySystemMediaCapability('%s','%s','%s') unsupported; "
+          "MIME type is not an audio or video MIME type.",
+          NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+          NS_ConvertUTF16toUTF8(contentTypeString).get(),
+          NS_ConvertUTF16toUTF8(robustness).get(),
+          NS_ConvertUTF16toUTF8(encryptionScheme).get());
+      continue;
+    }
+    if (majorType != aCodecType || !AllCodecsOfType(codecs, aCodecType)) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') "
+          "MediaKeySystemMediaCapability('%s','%s','%s') unsupported; "
+          "MIME type mixes audio codecs in video capabilities "
+          "or video codecs in audio capabilities.",
+          NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+          NS_ConvertUTF16toUTF8(contentTypeString).get(),
+          NS_ConvertUTF16toUTF8(robustness).get(),
+          NS_ConvertUTF16toUTF8(encryptionScheme).get());
+      continue;
+    }
+    // If robustness is not the empty string and contains an unrecognized
+    // value or a value not supported by implementation, continue to the
+    // next iteration. String comparison is case-sensitive.
+    if (!robustness.IsEmpty()) {
+      if (majorType == Audio &&
+          !aKeySystem.mAudioRobustness.Contains(robustness)) {
+        EME_LOG(
+            "MediaKeySystemConfiguration (label='%s') "
+            "MediaKeySystemMediaCapability('%s','%s','%s') unsupported; "
+            "unsupported robustness string.",
+            NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+            NS_ConvertUTF16toUTF8(contentTypeString).get(),
+            NS_ConvertUTF16toUTF8(robustness).get(),
+            NS_ConvertUTF16toUTF8(encryptionScheme).get());
+        continue;
+      }
+      if (majorType == Video &&
+          !aKeySystem.mVideoRobustness.Contains(robustness)) {
+        EME_LOG(
+            "MediaKeySystemConfiguration (label='%s') "
+            "MediaKeySystemMediaCapability('%s','%s','%s') unsupported; "
+            "unsupported robustness string.",
+            NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+            NS_ConvertUTF16toUTF8(contentTypeString).get(),
+            NS_ConvertUTF16toUTF8(robustness).get(),
+            NS_ConvertUTF16toUTF8(encryptionScheme).get());
+        continue;
+      }
+      // Note: specified robustness requirements are satisfied.
+    }
+
+    // If preffed on: "In the Get Supported Capabilities for Audio/Video Type
+    // algorithm, implementations must skip capabilities specifying unsupported
+    // encryption schemes."
+    if (!SupportsEncryptionScheme(encryptionScheme,
+                                  aKeySystem.mEncryptionSchemes)) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') "
+          "MediaKeySystemMediaCapability('%s','%s','%s') unsupported; "
+          "encryption scheme unsupported by CDM requested.",
+          NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+          NS_ConvertUTF16toUTF8(contentTypeString).get(),
+          NS_ConvertUTF16toUTF8(robustness).get(),
+          NS_ConvertUTF16toUTF8(encryptionScheme).get());
+      continue;
+    }
+
+    // If the user agent and implementation definitely support playback of
+    // encrypted media data for the combination of container, media types,
+    // robustness and local accumulated configuration in combination with
+    // restrictions...
+    const auto& containerSupport =
+        supportedInMP4 ? aKeySystem.mMP4 : aKeySystem.mWebM;
+    if (!CanDecryptAndDecode(aKeySystem.mKeySystem, contentTypeString,
+                             majorType, containerSupport, codecs,
+                             aDiagnostics)) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') "
+          "MediaKeySystemMediaCapability('%s','%s','%s') unsupported; "
+          "codec unsupported by CDM requested.",
+          NS_ConvertUTF16toUTF8(aPartialConfig.mLabel).get(),
+          NS_ConvertUTF16toUTF8(contentTypeString).get(),
+          NS_ConvertUTF16toUTF8(robustness).get(),
+          NS_ConvertUTF16toUTF8(encryptionScheme).get());
+      continue;
+    }
+
+    // ... add requested media capability to supported media capabilities.
+    if (!supportedCapabilities.AppendElement(capabilities, mozilla::fallible)) {
+      NS_WARNING("GetSupportedCapabilities: Malloc failure");
+      return Sequence<MediaKeySystemMediaCapability>();
+    }
+
+    // Note: omitting steps 3.13.2, our robustness is not sophisticated enough
+    // to require considering all requirements together.
+  }
+  return supportedCapabilities;
+}
+
+// "Get Supported Configuration and Consent" algorithm, steps 4-7 for
+// distinctive identifier, and steps 8-11 for persistent state. The steps
+// are the same for both requirements/features, so we factor them out into
+// a single function.
+static bool CheckRequirement(
+    const MediaKeysRequirement aRequirement,
+    const KeySystemConfig::Requirement aKeySystemRequirement,
+    MediaKeysRequirement& aOutRequirement) {
+  // Let requirement be the value of candidate configuration's member.
+  MediaKeysRequirement requirement = aRequirement;
+  // If requirement is "optional" and feature is not allowed according to
+  // restrictions, set requirement to "not-allowed".
+  if (aRequirement == MediaKeysRequirement::Optional &&
+      aKeySystemRequirement == KeySystemConfig::Requirement::NotAllowed) {
+    requirement = MediaKeysRequirement::Not_allowed;
+  }
+
+  // Follow the steps for requirement from the following list:
+  switch (requirement) {
+    case MediaKeysRequirement::Required: {
+      // If the implementation does not support use of requirement in
+      // combination with accumulated configuration and restrictions, return
+      // NotSupported.
+      if (aKeySystemRequirement == KeySystemConfig::Requirement::NotAllowed) {
+        return false;
+      }
+      break;
+    }
+    case MediaKeysRequirement::Optional: {
+      // Continue with the following steps.
+      break;
+    }
+    case MediaKeysRequirement::Not_allowed: {
+      // If the implementation requires use of feature in combination with
+      // accumulated configuration and restrictions, return NotSupported.
+      if (aKeySystemRequirement == KeySystemConfig::Requirement::Required) {
+        return false;
+      }
+      break;
+    }
+    default: {
+      return false;
+    }
+  }
+
+  // Set the requirement member of accumulated configuration to equal
+  // calculated requirement.
+  aOutRequirement = requirement;
+
+  return true;
+}
+
+// 3.1.1.2, step 12
+// Follow the steps for the first matching condition from the following list:
+// If the sessionTypes member is present in candidate configuration.
+// Let session types be candidate configuration's sessionTypes member.
+// Otherwise let session types be ["temporary"].
+// Note: This returns an empty array on malloc failure.
+static Sequence<nsString> UnboxSessionTypes(
+    const Optional<Sequence<nsString>>& aSessionTypes) {
+  Sequence<nsString> sessionTypes;
+  if (aSessionTypes.WasPassed()) {
+    sessionTypes = aSessionTypes.Value();
+  } else {
+    // Note: fallible. Results in an empty array.
+    (void)sessionTypes.AppendElement(ToString(MediaKeySessionType::Temporary),
+                                     mozilla::fallible);
+  }
+  return sessionTypes;
+}
+
+// 3.1.1.2 Get Supported Configuration and Consent
+static bool GetSupportedConfig(
+    const KeySystemConfig& aKeySystem,
+    const MediaKeySystemConfiguration& aCandidate,
+    MediaKeySystemConfiguration& aOutConfig,
+    DecoderDoctorDiagnostics* aDiagnostics, bool aInPrivateBrowsing,
+    const std::function<void(const char*)>& aDeprecationLogFn) {
+  EME_LOG("Compare implementation '%s'\n with request '%s'",
+          NS_ConvertUTF16toUTF8(aKeySystem.GetDebugInfo()).get(),
+          ToCString(aCandidate).get());
+  // Let accumulated configuration be a new MediaKeySystemConfiguration
+  // dictionary.
+  MediaKeySystemConfiguration config;
+  // Set the label member of accumulated configuration to equal the label member
+  // of candidate configuration.
+  config.mLabel = aCandidate.mLabel;
+  // If the initDataTypes member of candidate configuration is non-empty, run
+  // the following steps:
+  if (!aCandidate.mInitDataTypes.IsEmpty()) {
+    // Let supported types be an empty sequence of DOMStrings.
+    nsTArray<nsString> supportedTypes;
+    // For each value in candidate configuration's initDataTypes member:
+    for (const nsString& initDataType : aCandidate.mInitDataTypes) {
+      // Let initDataType be the value.
+      // If the implementation supports generating requests based on
+      // initDataType, add initDataType to supported types. String comparison is
+      // case-sensitive. The empty string is never supported.
+      if (aKeySystem.mInitDataTypes.Contains(initDataType)) {
+        supportedTypes.AppendElement(initDataType);
+      }
+    }
+    // If supported types is empty, return NotSupported.
+    if (supportedTypes.IsEmpty()) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') rejected; "
+          "no supported initDataTypes provided.",
+          NS_ConvertUTF16toUTF8(aCandidate.mLabel).get());
+      return false;
+    }
+    // Set the initDataTypes member of accumulated configuration to supported
+    // types.
+    if (!config.mInitDataTypes.Assign(supportedTypes)) {
+      return false;
+    }
+  }
+
+  if (!CheckRequirement(aCandidate.mDistinctiveIdentifier,
+                        aKeySystem.mDistinctiveIdentifier,
+                        config.mDistinctiveIdentifier)) {
+    EME_LOG(
+        "MediaKeySystemConfiguration (label='%s') rejected; "
+        "distinctiveIdentifier requirement not satisfied.",
+        NS_ConvertUTF16toUTF8(aCandidate.mLabel).get());
+    return false;
+  }
+
+  if (!CheckRequirement(aCandidate.mPersistentState,
+                        aKeySystem.mPersistentState, config.mPersistentState)) {
+    EME_LOG(
+        "MediaKeySystemConfiguration (label='%s') rejected; "
+        "persistentState requirement not satisfied.",
+        NS_ConvertUTF16toUTF8(aCandidate.mLabel).get());
+    return false;
+  }
+
+  if (config.mPersistentState == MediaKeysRequirement::Required &&
+      aInPrivateBrowsing) {
+    EME_LOG(
+        "MediaKeySystemConfiguration (label='%s') rejected; "
+        "persistentState requested in Private Browsing window.",
+        NS_ConvertUTF16toUTF8(aCandidate.mLabel).get());
+    return false;
+  }
+
+  Sequence<nsString> sessionTypes(UnboxSessionTypes(aCandidate.mSessionTypes));
+  if (sessionTypes.IsEmpty()) {
+    // Malloc failure.
+    return false;
+  }
+
+  // For each value in session types:
+  for (const auto& sessionTypeString : sessionTypes) {
+    // Let session type be the value.
+    MediaKeySessionType sessionType;
+    if (!ToSessionType(sessionTypeString, sessionType)) {
+      // (Assume invalid sessionType is unsupported as per steps below).
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') rejected; "
+          "invalid session type specified.",
+          NS_ConvertUTF16toUTF8(aCandidate.mLabel).get());
+      return false;
+    }
+    // If accumulated configuration's persistentState value is "not-allowed"
+    // and the Is persistent session type? algorithm returns true for session
+    // type return NotSupported.
+    if (config.mPersistentState == MediaKeysRequirement::Not_allowed &&
+        IsPersistentSessionType(sessionType)) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') rejected; "
+          "persistent session requested but keysystem doesn't"
+          "support persistent state.",
+          NS_ConvertUTF16toUTF8(aCandidate.mLabel).get());
+      return false;
+    }
+    // If the implementation does not support session type in combination
+    // with accumulated configuration and restrictions for other reasons,
+    // return NotSupported.
+    if (!ContainsSessionType(aKeySystem.mSessionTypes, sessionType)) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') rejected; "
+          "session type '%s' unsupported by keySystem.",
+          NS_ConvertUTF16toUTF8(aCandidate.mLabel).get(),
+          NS_ConvertUTF16toUTF8(sessionTypeString).get());
+      return false;
+    }
+    // If accumulated configuration's persistentState value is "optional"
+    // and the result of running the Is persistent session type? algorithm
+    // on session type is true, change accumulated configuration's
+    // persistentState value to "required".
+    if (config.mPersistentState == MediaKeysRequirement::Optional &&
+        IsPersistentSessionType(sessionType)) {
+      config.mPersistentState = MediaKeysRequirement::Required;
+    }
+  }
+  // Set the sessionTypes member of accumulated configuration to session types.
+  config.mSessionTypes.Construct(std::move(sessionTypes));
+
+  // If the videoCapabilities and audioCapabilities members in candidate
+  // configuration are both empty, return NotSupported.
+  if (aCandidate.mAudioCapabilities.IsEmpty() &&
+      aCandidate.mVideoCapabilities.IsEmpty()) {
+    // TODO: Most sites using EME still don't pass capabilities, so we
+    // can't reject on it yet without breaking them. So add this later.
+    // Log deprecation warning to encourage authors to not do this!
+    aDeprecationLogFn("MediaEMENoCapabilitiesDeprecatedWarning");
+  }
+
+  // If the videoCapabilities member in candidate configuration is non-empty:
+  if (!aCandidate.mVideoCapabilities.IsEmpty()) {
+    // Let video capabilities be the result of executing the Get Supported
+    // Capabilities for Audio/Video Type algorithm on Video, candidate
+    // configuration's videoCapabilities member, accumulated configuration,
+    // and restrictions.
+    Sequence<MediaKeySystemMediaCapability> caps =
+        GetSupportedCapabilities(Video, aCandidate.mVideoCapabilities, config,
+                                 aKeySystem, aDiagnostics, aDeprecationLogFn);
+    // If video capabilities is null, return NotSupported.
+    if (caps.IsEmpty()) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') rejected; "
+          "no supported video capabilities.",
+          NS_ConvertUTF16toUTF8(aCandidate.mLabel).get());
+      return false;
+    }
+    // Set the videoCapabilities member of accumulated configuration to video
+    // capabilities.
+    config.mVideoCapabilities = std::move(caps);
+  } else {
+    // Otherwise:
+    // Set the videoCapabilities member of accumulated configuration to an empty
+    // sequence.
+  }
+
+  // If the audioCapabilities member in candidate configuration is non-empty:
+  if (!aCandidate.mAudioCapabilities.IsEmpty()) {
+    // Let audio capabilities be the result of executing the Get Supported
+    // Capabilities for Audio/Video Type algorithm on Audio, candidate
+    // configuration's audioCapabilities member, accumulated configuration, and
+    // restrictions.
+    Sequence<MediaKeySystemMediaCapability> caps =
+        GetSupportedCapabilities(Audio, aCandidate.mAudioCapabilities, config,
+                                 aKeySystem, aDiagnostics, aDeprecationLogFn);
+    // If audio capabilities is null, return NotSupported.
+    if (caps.IsEmpty()) {
+      EME_LOG(
+          "MediaKeySystemConfiguration (label='%s') rejected; "
+          "no supported audio capabilities.",
+          NS_ConvertUTF16toUTF8(aCandidate.mLabel).get());
+      return false;
+    }
+    // Set the audioCapabilities member of accumulated configuration to audio
+    // capabilities.
+    config.mAudioCapabilities = std::move(caps);
+  } else {
+    // Otherwise:
+    // Set the audioCapabilities member of accumulated configuration to an empty
+    // sequence.
+  }
+
+  // If accumulated configuration's distinctiveIdentifier value is "optional",
+  // follow the steps for the first matching condition from the following list:
+  if (config.mDistinctiveIdentifier == MediaKeysRequirement::Optional) {
+    // If the implementation requires use Distinctive Identifier(s) or
+    // Distinctive Permanent Identifier(s) for any of the combinations
+    // in accumulated configuration
+    if (aKeySystem.mDistinctiveIdentifier ==
+        KeySystemConfig::Requirement::Required) {
+      // Change accumulated configuration's distinctiveIdentifier value to
+      // "required".
+      config.mDistinctiveIdentifier = MediaKeysRequirement::Required;
+    } else {
+      // Otherwise, change accumulated configuration's distinctiveIdentifier
+      // value to "not-allowed".
+      config.mDistinctiveIdentifier = MediaKeysRequirement::Not_allowed;
+    }
+  }
+
+  // If accumulated configuration's persistentState value is "optional", follow
+  // the steps for the first matching condition from the following list:
+  if (config.mPersistentState == MediaKeysRequirement::Optional) {
+    // If the implementation requires persisting state for any of the
+    // combinations in accumulated configuration
+    if (aKeySystem.mPersistentState == KeySystemConfig::Requirement::Required) {
+      // Change accumulated configuration's persistentState value to "required".
+      config.mPersistentState = MediaKeysRequirement::Required;
+    } else {
+      // Otherwise, change accumulated configuration's persistentState
+      // value to "not-allowed".
+      config.mPersistentState = MediaKeysRequirement::Not_allowed;
+    }
+  }
+
+  // Note: Omitting steps 20-22. We don't ask for consent.
+
+#if defined(XP_WIN)
+  // Widevine CDM doesn't include an AAC decoder. So if WMF can't decode AAC,
+  // and a codec wasn't specified, be conservative and reject the MediaKeys
+  // request.
+  if (IsWidevineKeySystem(aKeySystem.mKeySystem) &&
+      (aCandidate.mAudioCapabilities.IsEmpty() ||
+       aCandidate.mVideoCapabilities.IsEmpty()) &&
+      !WMFDecoderModule::CanCreateMFTDecoder(WMFStreamType::AAC)) {
+    if (aDiagnostics) {
+      aDiagnostics->SetKeySystemIssue(
+          DecoderDoctorDiagnostics::eWidevineWithNoWMF);
+    }
+    EME_LOG(
+        "MediaKeySystemConfiguration (label='%s') rejected; "
+        "WMF required for Widevine decoding, but it's not available.",
+        NS_ConvertUTF16toUTF8(aCandidate.mLabel).get());
+    return false;
+  }
+#endif
+
+  // Return accumulated configuration.
+  aOutConfig = config;
+
+  return true;
+}
+
+/* static */
+bool MediaKeySystemAccess::GetSupportedConfig(
+    const nsAString& aKeySystem,
+    const Sequence<MediaKeySystemConfiguration>& aConfigs,
+    MediaKeySystemConfiguration& aOutConfig,
+    DecoderDoctorDiagnostics* aDiagnostics, bool aIsPrivateBrowsing,
+    const std::function<void(const char*)>& aDeprecationLogFn) {
+  nsTArray<KeySystemConfig> implementations;
+  if (!GetKeySystemConfigs(aKeySystem, implementations)) {
+    return false;
+  }
+  for (const auto& implementation : implementations) {
+    for (const MediaKeySystemConfiguration& candidate : aConfigs) {
+      if (mozilla::dom::GetSupportedConfig(
+              implementation, candidate, aOutConfig, aDiagnostics,
+              aIsPrivateBrowsing, aDeprecationLogFn)) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+/* static */
+void MediaKeySystemAccess::NotifyObservers(nsPIDOMWindowInner* aWindow,
+                                           const nsAString& aKeySystem,
+                                           MediaKeySystemStatus aStatus) {
+  RequestMediaKeySystemAccessNotification data;
+  data.mKeySystem = aKeySystem;
+  data.mStatus = aStatus;
+  nsAutoString json;
+  data.ToJSON(json);
+  EME_LOG("MediaKeySystemAccess::NotifyObservers() %s",
+          NS_ConvertUTF16toUTF8(json).get());
+  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
+  if (obs) {
+    obs->NotifyObservers(aWindow, MediaKeys::kMediaKeysRequestTopic,
+                         json.get());
+  }
+}
+
+static nsCString ToCString(const nsString& aString) {
+  nsCString str("'");
+  str.Append(NS_ConvertUTF16toUTF8(aString));
+  str.AppendLiteral("'");
+  return str;
+}
+
+static nsCString ToCString(const MediaKeysRequirement aValue) {
+  nsCString str("'");
+  str.AppendASCII(MediaKeysRequirementValues::GetString(aValue));
+  str.AppendLiteral("'");
+  return str;
+}
+
+static nsCString ToCString(const MediaKeySystemMediaCapability& aValue) {
+  nsCString str;
+  str.AppendLiteral("{contentType=");
+  str.Append(ToCString(aValue.mContentType));
+  str.AppendLiteral(", robustness=");
+  str.Append(ToCString(aValue.mRobustness));
+  str.AppendLiteral(", encryptionScheme=");
+  str.Append(ToCString(aValue.mEncryptionScheme));
+  str.AppendLiteral("}");
+  return str;
+}
+
+template <class Type>
+static nsCString ToCString(const Sequence<Type>& aSequence) {
+  nsCString str;
+  str.AppendLiteral("[");
+  StringJoinAppend(str, ","_ns, aSequence,
+                   [](nsACString& dest, const Type& element) {
+                     dest.Append(ToCString(element));
+                   });
+  str.AppendLiteral("]");
+  return str;
+}
+
+template <class Type>
+static nsCString ToCString(const Optional<Sequence<Type>>& aOptional) {
+  nsCString str;
+  if (aOptional.WasPassed()) {
+    str.Append(ToCString(aOptional.Value()));
+  } else {
+    str.AppendLiteral("[]");
+  }
+  return str;
+}
+
+static nsCString ToCString(const MediaKeySystemConfiguration& aConfig) {
+  nsCString str;
+  str.AppendLiteral("{label=");
+  str.Append(ToCString(aConfig.mLabel));
+
+  str.AppendLiteral(", initDataTypes=");
+  str.Append(ToCString(aConfig.mInitDataTypes));
+
+  str.AppendLiteral(", audioCapabilities=");
+  str.Append(ToCString(aConfig.mAudioCapabilities));
+
+  str.AppendLiteral(", videoCapabilities=");
+  str.Append(ToCString(aConfig.mVideoCapabilities));
+
+  str.AppendLiteral(", distinctiveIdentifier=");
+  str.Append(ToCString(aConfig.mDistinctiveIdentifier));
+
+  str.AppendLiteral(", persistentState=");
+  str.Append(ToCString(aConfig.mPersistentState));
+
+  str.AppendLiteral(", sessionTypes=");
+  str.Append(ToCString(aConfig.mSessionTypes));
+
+  str.AppendLiteral("}");
+
+  return str;
+}
+
+/* static */
+nsCString MediaKeySystemAccess::ToCString(
+    const Sequence<MediaKeySystemConfiguration>& aConfig) {
+  return mozilla::dom::ToCString(aConfig);
+}
+
+#undef LOG
+
+}  // namespace mozilla::dom