Adding upstream version 110.0.1.upstream/110.0.1upstream

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

1 files changed, 1316 insertions, 0 deletions

diff --git a/dom/media/eme/MediaKeySystemAccess.cpp b/dom/media/eme/MediaKeySystemAccess.cpp
new file mode 100644
index 0000000000..ed2a8a8200
--- /dev/null
+++ b/dom/media/eme/MediaKeySystemAccess.cpp
@@ -0,0 +1,1316 @@
+/* -*- 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 "GMPUtils.h"
+#include "MediaContainerType.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/dom/KeySystemNames.h"
+#include "mozilla/dom/MediaKeySystemAccessBinding.h"
+#include "mozilla/dom/MediaKeySession.h"
+#include "mozilla/dom/MediaSource.h"
+#include "mozilla/EMEUtils.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/Services.h"
+#include "mozilla/StaticPrefs_media.h"
+#include "nsDOMString.h"
+#include "nsIObserverService.h"
+#include "nsMimeTypes.h"
+#include "nsReadableUtils.h"
+#include "nsServiceManagerUtils.h"
+#include "nsUnicharUtils.h"
+#include "WebMDecoder.h"
+
+#ifdef XP_WIN
+#  include "WMFDecoderModule.h"
+#endif
+#ifdef MOZ_WIDGET_ANDROID
+#  include "AndroidDecoderModule.h"
+#  include "mozilla/java/MediaDrmProxyWrappers.h"
+#endif
+
+namespace mozilla::dom {
+
+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) {
+  EME_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);
+}
+
+static bool HavePluginForKeySystem(const nsCString& aKeySystem) {
+  nsCString api = nsLiteralCString(CHROMIUM_CDM_API);
+
+  bool havePlugin = HaveGMPFor(api, {aKeySystem});
+#ifdef MOZ_WIDGET_ANDROID
+  // Check if we can use MediaDrm for this keysystem.
+  if (!havePlugin) {
+    havePlugin = mozilla::java::MediaDrmProxy::IsSchemeSupported(aKeySystem);
+  }
+#endif
+  return havePlugin;
+}
+
+static MediaKeySystemStatus EnsureCDMInstalled(const nsAString& aKeySystem,
+                                               nsACString& aOutMessage) {
+  if (!HavePluginForKeySystem(NS_ConvertUTF16toUTF8(aKeySystem))) {
+    aOutMessage = "CDM is not installed"_ns;
+    return MediaKeySystemStatus::Cdm_not_installed;
+  }
+
+  return MediaKeySystemStatus::Available;
+}
+
+/* static */
+MediaKeySystemStatus MediaKeySystemAccess::GetKeySystemStatus(
+    const nsAString& aKeySystem, nsACString& aOutMessage) {
+  MOZ_ASSERT(StaticPrefs::media_eme_enabled() ||
+             IsClearkeyKeySystem(aKeySystem));
+
+  if (IsClearkeyKeySystem(aKeySystem)) {
+    return EnsureCDMInstalled(aKeySystem, aOutMessage);
+  }
+
+  if (IsWidevineKeySystem(aKeySystem)) {
+    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(aKeySystem, aOutMessage);
+#ifdef MOZ_WIDGET_ANDROID
+    } else if (Preferences::GetBool("media.mediadrm-widevinecdm.visible",
+                                    false)) {
+      nsCString keySystem = NS_ConvertUTF16toUTF8(aKeySystem);
+      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
+    }
+  }
+
+  return MediaKeySystemStatus::Cdm_not_supported;
+}
+
+typedef nsCString EMECodecString;
+
+static constexpr auto EME_CODEC_AAC = "aac"_ns;
+static constexpr auto EME_CODEC_OPUS = "opus"_ns;
+static constexpr auto EME_CODEC_VORBIS = "vorbis"_ns;
+static constexpr auto EME_CODEC_FLAC = "flac"_ns;
+static constexpr auto EME_CODEC_H264 = "h264"_ns;
+static constexpr auto EME_CODEC_VP8 = "vp8"_ns;
+static constexpr auto EME_CODEC_VP9 = "vp9"_ns;
+
+EMECodecString ToEMEAPICodecString(const nsString& aCodec) {
+  if (IsAACCodecString(aCodec)) {
+    return EME_CODEC_AAC;
+  }
+  if (aCodec.EqualsLiteral("opus")) {
+    return EME_CODEC_OPUS;
+  }
+  if (aCodec.EqualsLiteral("vorbis")) {
+    return EME_CODEC_VORBIS;
+  }
+  if (aCodec.EqualsLiteral("flac")) {
+    return EME_CODEC_FLAC;
+  }
+  if (IsH264CodecString(aCodec)) {
+    return EME_CODEC_H264;
+  }
+  if (IsVP8CodecString(aCodec)) {
+    return EME_CODEC_VP8;
+  }
+  if (IsVP9CodecString(aCodec)) {
+    return EME_CODEC_VP9;
+  }
+  return ""_ns;
+}
+
+// A codec can be decrypted-and-decoded by the CDM, or only decrypted
+// by the CDM and decoded by Gecko. Not both.
+struct KeySystemContainerSupport {
+  KeySystemContainerSupport() = default;
+  ~KeySystemContainerSupport() = default;
+  KeySystemContainerSupport(const KeySystemContainerSupport& aOther) {
+    mCodecsDecoded = aOther.mCodecsDecoded.Clone();
+    mCodecsDecrypted = aOther.mCodecsDecrypted.Clone();
+  }
+  KeySystemContainerSupport& operator=(
+      const KeySystemContainerSupport& aOther) {
+    if (this == &aOther) {
+      return *this;
+    }
+    mCodecsDecoded = aOther.mCodecsDecoded.Clone();
+    mCodecsDecrypted = aOther.mCodecsDecrypted.Clone();
+    return *this;
+  }
+  KeySystemContainerSupport(KeySystemContainerSupport&& aOther) = default;
+  KeySystemContainerSupport& operator=(KeySystemContainerSupport&&) = default;
+
+  bool IsSupported() const {
+    return !mCodecsDecoded.IsEmpty() || !mCodecsDecrypted.IsEmpty();
+  }
+
+  // CDM decrypts and decodes using a DRM robust decoder, and passes decoded
+  // samples back to Gecko for rendering.
+  bool DecryptsAndDecodes(EMECodecString aCodec) const {
+    return mCodecsDecoded.Contains(aCodec);
+  }
+
+  // CDM decrypts and passes the decrypted samples back to Gecko for decoding.
+  bool Decrypts(EMECodecString aCodec) const {
+    return mCodecsDecrypted.Contains(aCodec);
+  }
+
+  void SetCanDecryptAndDecode(EMECodecString aCodec) {
+    // Can't both decrypt and decrypt-and-decode a codec.
+    MOZ_ASSERT(!Decrypts(aCodec));
+    // Prevent duplicates.
+    MOZ_ASSERT(!DecryptsAndDecodes(aCodec));
+    mCodecsDecoded.AppendElement(aCodec);
+  }
+
+  void SetCanDecrypt(EMECodecString aCodec) {
+    // Prevent duplicates.
+    MOZ_ASSERT(!Decrypts(aCodec));
+    // Can't both decrypt and decrypt-and-decode a codec.
+    MOZ_ASSERT(!DecryptsAndDecodes(aCodec));
+    mCodecsDecrypted.AppendElement(aCodec);
+  }
+
+ private:
+  nsTArray<EMECodecString> mCodecsDecoded;
+  nsTArray<EMECodecString> mCodecsDecrypted;
+};
+
+enum class KeySystemFeatureSupport {
+  Prohibited = 1,
+  Requestable = 2,
+  Required = 3,
+};
+
+struct KeySystemConfig {
+  KeySystemConfig() = default;
+  ~KeySystemConfig() = default;
+  KeySystemConfig(const KeySystemConfig& aOther) {
+    mKeySystem = aOther.mKeySystem;
+    mInitDataTypes = aOther.mInitDataTypes.Clone();
+    mPersistentState = aOther.mPersistentState;
+    mDistinctiveIdentifier = aOther.mDistinctiveIdentifier;
+    mSessionTypes = aOther.mSessionTypes.Clone();
+    mVideoRobustness = aOther.mVideoRobustness.Clone();
+    mAudioRobustness = aOther.mAudioRobustness.Clone();
+    mEncryptionSchemes = aOther.mEncryptionSchemes.Clone();
+    mMP4 = aOther.mMP4;
+    mWebM = aOther.mWebM;
+  }
+  KeySystemConfig& operator=(const KeySystemConfig& aOther) {
+    if (this == &aOther) {
+      return *this;
+    }
+    mKeySystem = aOther.mKeySystem;
+    mInitDataTypes = aOther.mInitDataTypes.Clone();
+    mPersistentState = aOther.mPersistentState;
+    mDistinctiveIdentifier = aOther.mDistinctiveIdentifier;
+    mSessionTypes = aOther.mSessionTypes.Clone();
+    mVideoRobustness = aOther.mVideoRobustness.Clone();
+    mAudioRobustness = aOther.mAudioRobustness.Clone();
+    mEncryptionSchemes = aOther.mEncryptionSchemes.Clone();
+    mMP4 = aOther.mMP4;
+    mWebM = aOther.mWebM;
+    return *this;
+  }
+  KeySystemConfig(KeySystemConfig&&) = default;
+  KeySystemConfig& operator=(KeySystemConfig&&) = default;
+
+  nsString mKeySystem;
+  nsTArray<nsString> mInitDataTypes;
+  KeySystemFeatureSupport mPersistentState =
+      KeySystemFeatureSupport::Prohibited;
+  KeySystemFeatureSupport mDistinctiveIdentifier =
+      KeySystemFeatureSupport::Prohibited;
+  nsTArray<MediaKeySessionType> mSessionTypes;
+  nsTArray<nsString> mVideoRobustness;
+  nsTArray<nsString> mAudioRobustness;
+  nsTArray<nsString> mEncryptionSchemes;
+  KeySystemContainerSupport mMP4;
+  KeySystemContainerSupport mWebM;
+};
+
+static nsTArray<KeySystemConfig> GetSupportedKeySystems() {
+  nsTArray<KeySystemConfig> keySystemConfigs;
+
+  {
+    const nsCString keySystem = nsLiteralCString(kClearKeyKeySystemName);
+    if (HavePluginForKeySystem(keySystem)) {
+      KeySystemConfig clearkey;
+      clearkey.mKeySystem.AssignLiteral(kClearKeyKeySystemName);
+      clearkey.mInitDataTypes.AppendElement(u"cenc"_ns);
+      clearkey.mInitDataTypes.AppendElement(u"keyids"_ns);
+      clearkey.mInitDataTypes.AppendElement(u"webm"_ns);
+      clearkey.mPersistentState = KeySystemFeatureSupport::Requestable;
+      clearkey.mDistinctiveIdentifier = KeySystemFeatureSupport::Prohibited;
+      clearkey.mSessionTypes.AppendElement(MediaKeySessionType::Temporary);
+      clearkey.mEncryptionSchemes.AppendElement(u"cenc"_ns);
+      clearkey.mEncryptionSchemes.AppendElement(u"cbcs"_ns);
+      clearkey.mEncryptionSchemes.AppendElement(u"cbcs-1-9"_ns);
+      if (StaticPrefs::media_clearkey_persistent_license_enabled()) {
+        clearkey.mSessionTypes.AppendElement(
+            MediaKeySessionType::Persistent_license);
+      }
+#if defined(XP_WIN)
+      // Clearkey CDM uses WMF's H.264 decoder on Windows.
+      if (WMFDecoderModule::CanCreateMFTDecoder(WMFStreamType::H264)) {
+        clearkey.mMP4.SetCanDecryptAndDecode(EME_CODEC_H264);
+      } else {
+        clearkey.mMP4.SetCanDecrypt(EME_CODEC_H264);
+      }
+#else
+      clearkey.mMP4.SetCanDecrypt(EME_CODEC_H264);
+#endif
+      clearkey.mMP4.SetCanDecrypt(EME_CODEC_AAC);
+      clearkey.mMP4.SetCanDecrypt(EME_CODEC_FLAC);
+      clearkey.mMP4.SetCanDecrypt(EME_CODEC_OPUS);
+      clearkey.mMP4.SetCanDecrypt(EME_CODEC_VP9);
+      clearkey.mWebM.SetCanDecrypt(EME_CODEC_VORBIS);
+      clearkey.mWebM.SetCanDecrypt(EME_CODEC_OPUS);
+      clearkey.mWebM.SetCanDecrypt(EME_CODEC_VP8);
+      clearkey.mWebM.SetCanDecrypt(EME_CODEC_VP9);
+
+      if (StaticPrefs::media_clearkey_test_key_systems_enabled()) {
+        // Add testing key systems. These offer the same capabilities as the
+        // base clearkey system, so just clone clearkey and change the name.
+        KeySystemConfig clearkeyWithProtectionQuery{clearkey};
+        clearkeyWithProtectionQuery.mKeySystem.AssignLiteral(
+            kClearKeyWithProtectionQueryKeySystemName);
+        keySystemConfigs.AppendElement(std::move(clearkeyWithProtectionQuery));
+      }
+
+      keySystemConfigs.AppendElement(std::move(clearkey));
+    }
+  }
+  {
+    const nsCString keySystem = nsLiteralCString(kWidevineKeySystemName);
+    if (HavePluginForKeySystem(keySystem)) {
+      KeySystemConfig widevine;
+      widevine.mKeySystem.AssignLiteral(kWidevineKeySystemName);
+      widevine.mInitDataTypes.AppendElement(u"cenc"_ns);
+      widevine.mInitDataTypes.AppendElement(u"keyids"_ns);
+      widevine.mInitDataTypes.AppendElement(u"webm"_ns);
+      widevine.mPersistentState = KeySystemFeatureSupport::Requestable;
+      widevine.mDistinctiveIdentifier = KeySystemFeatureSupport::Prohibited;
+      widevine.mSessionTypes.AppendElement(MediaKeySessionType::Temporary);
+#ifdef MOZ_WIDGET_ANDROID
+      widevine.mSessionTypes.AppendElement(
+          MediaKeySessionType::Persistent_license);
+#endif
+      widevine.mAudioRobustness.AppendElement(u"SW_SECURE_CRYPTO"_ns);
+      widevine.mVideoRobustness.AppendElement(u"SW_SECURE_CRYPTO"_ns);
+      widevine.mVideoRobustness.AppendElement(u"SW_SECURE_DECODE"_ns);
+      widevine.mEncryptionSchemes.AppendElement(u"cenc"_ns);
+      widevine.mEncryptionSchemes.AppendElement(u"cbcs"_ns);
+      widevine.mEncryptionSchemes.AppendElement(u"cbcs-1-9"_ns);
+
+#if defined(MOZ_WIDGET_ANDROID)
+      // MediaDrm.isCryptoSchemeSupported only allows passing
+      // "video/mp4" or "video/webm" for mimetype string.
+      // See
+      // https://developer.android.com/reference/android/media/MediaDrm.html#isCryptoSchemeSupported(java.util.UUID,
+      // java.lang.String) for more detail.
+      typedef struct {
+        const nsCString& mMimeType;
+        const nsCString& mEMECodecType;
+        const char16_t* mCodecType;
+        KeySystemContainerSupport* mSupportType;
+      } DataForValidation;
+
+      DataForValidation validationList[] = {
+          {nsCString(VIDEO_MP4), EME_CODEC_H264, java::MediaDrmProxy::AVC,
+           &widevine.mMP4},
+          {nsCString(VIDEO_MP4), EME_CODEC_VP9, java::MediaDrmProxy::AVC,
+           &widevine.mMP4},
+          {nsCString(AUDIO_MP4), EME_CODEC_AAC, java::MediaDrmProxy::AAC,
+           &widevine.mMP4},
+          {nsCString(AUDIO_MP4), EME_CODEC_FLAC, java::MediaDrmProxy::FLAC,
+           &widevine.mMP4},
+          {nsCString(AUDIO_MP4), EME_CODEC_OPUS, java::MediaDrmProxy::OPUS,
+           &widevine.mMP4},
+          {nsCString(VIDEO_WEBM), EME_CODEC_VP8, java::MediaDrmProxy::VP8,
+           &widevine.mWebM},
+          {nsCString(VIDEO_WEBM), EME_CODEC_VP9, java::MediaDrmProxy::VP9,
+           &widevine.mWebM},
+          {nsCString(AUDIO_WEBM), EME_CODEC_VORBIS, java::MediaDrmProxy::VORBIS,
+           &widevine.mWebM},
+          {nsCString(AUDIO_WEBM), EME_CODEC_OPUS, java::MediaDrmProxy::OPUS,
+           &widevine.mWebM},
+      };
+
+      for (const auto& data : validationList) {
+        if (java::MediaDrmProxy::IsCryptoSchemeSupported(kWidevineKeySystemName,
+                                                         data.mMimeType)) {
+          if (AndroidDecoderModule::SupportsMimeType(data.mMimeType) !=
+              media::DecodeSupport::Unsupported) {
+            data.mSupportType->SetCanDecryptAndDecode(data.mEMECodecType);
+          } else {
+            data.mSupportType->SetCanDecrypt(data.mEMECodecType);
+          }
+        }
+      }
+#else
+#  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 (WMFDecoderModule::CanCreateMFTDecoder(WMFStreamType::AAC)) {
+        widevine.mMP4.SetCanDecrypt(EME_CODEC_AAC);
+      }
+#  else
+      widevine.mMP4.SetCanDecrypt(EME_CODEC_AAC);
+#  endif
+      widevine.mMP4.SetCanDecrypt(EME_CODEC_FLAC);
+      widevine.mMP4.SetCanDecrypt(EME_CODEC_OPUS);
+      widevine.mMP4.SetCanDecryptAndDecode(EME_CODEC_H264);
+      widevine.mMP4.SetCanDecryptAndDecode(EME_CODEC_VP9);
+      widevine.mWebM.SetCanDecrypt(EME_CODEC_VORBIS);
+      widevine.mWebM.SetCanDecrypt(EME_CODEC_OPUS);
+      widevine.mWebM.SetCanDecryptAndDecode(EME_CODEC_VP8);
+      widevine.mWebM.SetCanDecryptAndDecode(EME_CODEC_VP9);
+#endif
+      keySystemConfigs.AppendElement(std::move(widevine));
+    }
+  }
+
+  return keySystemConfigs;
+}
+
+static bool GetKeySystemConfig(const nsAString& aKeySystem,
+                               KeySystemConfig& aOutKeySystemConfig) {
+  for (auto&& config : GetSupportedKeySystems()) {
+    if (config.mKeySystem.Equals(aKeySystem)) {
+      aOutKeySystemConfig = std::move(config);
+      return true;
+    }
+  }
+  // No matching key system found.
+  return false;
+}
+
+/* static */
+bool MediaKeySystemAccess::KeySystemSupportsInitDataType(
+    const nsAString& aKeySystem, const nsAString& aInitDataType) {
+  KeySystemConfig implementation;
+  return GetKeySystemConfig(aKeySystem, implementation) &&
+         implementation.mInitDataTypes.Contains(aInitDataType);
+}
+
+enum CodecType { Audio, Video, Invalid };
+
+static bool CanDecryptAndDecode(
+    const nsString& aKeySystem, const nsString& aContentType,
+    CodecType aCodecType, const KeySystemContainerSupport& aContainerSupport,
+    const nsTArray<EMECodecString>& aCodecs,
+    DecoderDoctorDiagnostics* aDiagnostics) {
+  MOZ_ASSERT(aCodecType != Invalid);
+  for (const 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 == 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;
+}
+
+CodecType GetMajorType(const MediaMIMEType& aMIMEType) {
+  if (aMIMEType.HasAudioMajorType()) {
+    return Audio;
+  }
+  if (aMIMEType.HasVideoMajorType()) {
+    return Video;
+  }
+  return Invalid;
+}
+
+static CodecType GetCodecType(const EMECodecString& aCodec) {
+  if (aCodec.Equals(EME_CODEC_AAC) || aCodec.Equals(EME_CODEC_OPUS) ||
+      aCodec.Equals(EME_CODEC_VORBIS) || aCodec.Equals(EME_CODEC_FLAC)) {
+    return Audio;
+  }
+  if (aCodec.Equals(EME_CODEC_H264) || aCodec.Equals(EME_CODEC_VP8) ||
+      aCodec.Equals(EME_CODEC_VP9)) {
+    return Video;
+  }
+  return Invalid;
+}
+
+static bool AllCodecsOfType(const nsTArray<EMECodecString>& aCodecs,
+                            const CodecType aCodecType) {
+  for (const 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<EMECodecString> codecs;
+    for (const auto& codecString :
+         containerType.ExtendedType().Codecs().Range()) {
+      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 isMP4 =
+        DecoderTraits::IsMP4SupportedType(containerType, aDiagnostics);
+    if (isMP4 && !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 (!isMP4 && !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 (isMP4) {
+        if (aCodecType == Audio) {
+          codecs.AppendElement(EME_CODEC_AAC);
+        } else if (aCodecType == Video) {
+          codecs.AppendElement(EME_CODEC_H264);
+        }
+      } else if (isWebM) {
+        if (aCodecType == Audio) {
+          codecs.AppendElement(EME_CODEC_VORBIS);
+        } else if (aCodecType == Video) {
+          codecs.AppendElement(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 = isMP4 ? 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 KeySystemFeatureSupport aFeatureSupport,
+                             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 &&
+      aFeatureSupport == KeySystemFeatureSupport::Prohibited) {
+    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 (aFeatureSupport == KeySystemFeatureSupport::Prohibited) {
+        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 (aFeatureSupport == KeySystemFeatureSupport::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) {
+  // 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 (!aKeySystem.mSessionTypes.Contains(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 ==
+        KeySystemFeatureSupport::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 == KeySystemFeatureSupport::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) {
+  KeySystemConfig implementation;
+  if (!GetKeySystemConfig(aKeySystem, implementation)) {
+    return false;
+  }
+  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);
+}
+
+}  // namespace mozilla::dom