Adding upstream version 115.8.0esr.upstream/115.8.0esr

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

44 files changed, 8094 insertions, 0 deletions

diff --git a/dom/media/eme/CDMCaps.cpp b/dom/media/eme/CDMCaps.cpp
new file mode 100644
index 0000000000..2752ada476
--- /dev/null
+++ b/dom/media/eme/CDMCaps.cpp
@@ -0,0 +1,112 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/CDMCaps.h"
+#include "mozilla/EMEUtils.h"
+#include "nsThreadUtils.h"
+#include "SamplesWaitingForKey.h"
+
+namespace mozilla {
+
+CDMCaps::CDMCaps() = default;
+
+CDMCaps::~CDMCaps() = default;
+
+// Keys with MediaKeyStatus::Usable, MediaKeyStatus::Output_downscaled,
+// or MediaKeyStatus::Output_restricted status can be used by the CDM
+// to decrypt or decrypt-and-decode samples.
+static bool IsUsableStatus(dom::MediaKeyStatus aStatus) {
+  return aStatus == dom::MediaKeyStatus::Usable ||
+         aStatus == dom::MediaKeyStatus::Output_restricted ||
+         aStatus == dom::MediaKeyStatus::Output_downscaled;
+}
+
+bool CDMCaps::IsKeyUsable(const CencKeyId& aKeyId) {
+  for (const KeyStatus& keyStatus : mKeyStatuses) {
+    if (keyStatus.mId == aKeyId) {
+      return IsUsableStatus(keyStatus.mStatus);
+    }
+  }
+  return false;
+}
+
+bool CDMCaps::SetKeyStatus(const CencKeyId& aKeyId, const nsString& aSessionId,
+                           const dom::Optional<dom::MediaKeyStatus>& aStatus) {
+  if (!aStatus.WasPassed()) {
+    // Called from ForgetKeyStatus.
+    // Return true if the element is found to notify key changes.
+    return mKeyStatuses.RemoveElement(
+        KeyStatus(aKeyId, aSessionId, dom::MediaKeyStatus::Internal_error));
+  }
+
+  KeyStatus key(aKeyId, aSessionId, aStatus.Value());
+  auto index = mKeyStatuses.IndexOf(key);
+  if (index != mKeyStatuses.NoIndex) {
+    if (mKeyStatuses[index].mStatus == aStatus.Value()) {
+      // No change.
+      return false;
+    }
+    auto oldStatus = mKeyStatuses[index].mStatus;
+    mKeyStatuses[index].mStatus = aStatus.Value();
+    // The old key status was one for which we can decrypt media. We don't
+    // need to do the "notify usable" step below, as it should be impossible
+    // for us to have anything waiting on this key to become usable, since it
+    // was already usable.
+    if (IsUsableStatus(oldStatus)) {
+      return true;
+    }
+  } else {
+    mKeyStatuses.AppendElement(key);
+  }
+
+  // Only call NotifyUsable() for a key when we are going from non-usable
+  // to usable state.
+  if (!IsUsableStatus(aStatus.Value())) {
+    return true;
+  }
+
+  auto& waiters = mWaitForKeys;
+  size_t i = 0;
+  while (i < waiters.Length()) {
+    auto& w = waiters[i];
+    if (w.mKeyId == aKeyId) {
+      w.mListener->NotifyUsable(aKeyId);
+      waiters.RemoveElementAt(i);
+    } else {
+      i++;
+    }
+  }
+  return true;
+}
+
+void CDMCaps::NotifyWhenKeyIdUsable(const CencKeyId& aKey,
+                                    SamplesWaitingForKey* aListener) {
+  MOZ_ASSERT(!IsKeyUsable(aKey));
+  MOZ_ASSERT(aListener);
+  mWaitForKeys.AppendElement(WaitForKeys(aKey, aListener));
+}
+
+void CDMCaps::GetKeyStatusesForSession(const nsAString& aSessionId,
+                                       nsTArray<KeyStatus>& aOutKeyStatuses) {
+  for (const KeyStatus& keyStatus : mKeyStatuses) {
+    if (keyStatus.mSessionId.Equals(aSessionId)) {
+      aOutKeyStatuses.AppendElement(keyStatus);
+    }
+  }
+}
+
+bool CDMCaps::RemoveKeysForSession(const nsString& aSessionId) {
+  bool changed = false;
+  nsTArray<KeyStatus> statuses;
+  GetKeyStatusesForSession(aSessionId, statuses);
+  for (const KeyStatus& status : statuses) {
+    changed |= SetKeyStatus(status.mId, aSessionId,
+                            dom::Optional<dom::MediaKeyStatus>());
+  }
+  return changed;
+}
+
+}  // namespace mozilla
diff --git a/dom/media/eme/CDMCaps.h b/dom/media/eme/CDMCaps.h
new file mode 100644
index 0000000000..b16c5153b1
--- /dev/null
+++ b/dom/media/eme/CDMCaps.h
@@ -0,0 +1,82 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef CDMCaps_h_
+#define CDMCaps_h_
+
+#include "nsTArray.h"
+#include "nsString.h"
+#include "SamplesWaitingForKey.h"
+
+#include "mozilla/Monitor.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/dom/MediaKeyStatusMapBinding.h"  // For MediaKeyStatus
+#include "mozilla/dom/BindingDeclarations.h"       // For Optional
+
+namespace mozilla {
+
+// CDM capabilities; what keys a CDMProxy can use.
+// Must be locked to access state.
+class CDMCaps {
+ public:
+  CDMCaps();
+  ~CDMCaps();
+
+  struct KeyStatus {
+    KeyStatus(const CencKeyId& aId, const nsString& aSessionId,
+              dom::MediaKeyStatus aStatus)
+        : mId(aId.Clone()), mSessionId(aSessionId), mStatus(aStatus) {}
+    KeyStatus(const KeyStatus& aOther)
+        : mId(aOther.mId.Clone()),
+          mSessionId(aOther.mSessionId),
+          mStatus(aOther.mStatus) {}
+    bool operator==(const KeyStatus& aOther) const {
+      return mId == aOther.mId && mSessionId == aOther.mSessionId;
+    };
+
+    CencKeyId mId;
+    nsString mSessionId;
+    dom::MediaKeyStatus mStatus;
+  };
+
+  bool IsKeyUsable(const CencKeyId& aKeyId);
+
+  // Returns true if key status changed,
+  // i.e. the key status changed from usable to expired.
+  bool SetKeyStatus(const CencKeyId& aKeyId, const nsString& aSessionId,
+                    const dom::Optional<dom::MediaKeyStatus>& aStatus);
+
+  void GetKeyStatusesForSession(const nsAString& aSessionId,
+                                nsTArray<KeyStatus>& aOutKeyStatuses);
+
+  // Ensures all keys for a session are marked as 'unknown', i.e. removed.
+  // Returns true if a key status was changed.
+  bool RemoveKeysForSession(const nsString& aSessionId);
+
+  // Notifies the SamplesWaitingForKey when key become usable.
+  void NotifyWhenKeyIdUsable(const CencKeyId& aKey,
+                             SamplesWaitingForKey* aSamplesWaiting);
+
+ private:
+  struct WaitForKeys {
+    WaitForKeys(const CencKeyId& aKeyId, SamplesWaitingForKey* aListener)
+        : mKeyId(aKeyId.Clone()), mListener(aListener) {}
+    CencKeyId mKeyId;
+    RefPtr<SamplesWaitingForKey> mListener;
+  };
+
+  nsTArray<KeyStatus> mKeyStatuses;
+
+  nsTArray<WaitForKeys> mWaitForKeys;
+
+  // It is not safe to copy this object.
+  CDMCaps(const CDMCaps&) = delete;
+  CDMCaps& operator=(const CDMCaps&) = delete;
+};
+
+}  // namespace mozilla
+
+#endif
diff --git a/dom/media/eme/CDMProxy.h b/dom/media/eme/CDMProxy.h
new file mode 100644
index 0000000000..e638be3358
--- /dev/null
+++ b/dom/media/eme/CDMProxy.h
@@ -0,0 +1,323 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef CDMProxy_h_
+#define CDMProxy_h_
+
+#include "mozilla/CDMCaps.h"
+#include "mozilla/DataMutex.h"
+#include "mozilla/MozPromise.h"
+
+#include "mozilla/dom/MediaKeyMessageEvent.h"
+#include "mozilla/dom/MediaKeys.h"
+
+#include "nsIThread.h"
+
+namespace mozilla {
+class ErrorResult;
+class MediaRawData;
+class ChromiumCDMProxy;
+#ifdef MOZ_WMF_CDM
+class WMFCDMProxy;
+#endif
+
+namespace eme {
+enum DecryptStatus {
+  Ok = 0,
+  GenericErr = 1,
+  NoKeyErr = 2,
+  AbortedErr = 3,
+};
+}
+
+using eme::DecryptStatus;
+
+struct DecryptResult {
+  DecryptResult(DecryptStatus aStatus, MediaRawData* aSample)
+      : mStatus(aStatus), mSample(aSample) {}
+  DecryptStatus mStatus;
+  RefPtr<MediaRawData> mSample;
+};
+
+typedef MozPromise<DecryptResult, DecryptResult, /* IsExclusive = */ true>
+    DecryptPromise;
+
+class CDMKeyInfo {
+ public:
+  explicit CDMKeyInfo(const nsTArray<uint8_t>& aKeyId)
+      : mKeyId(aKeyId.Clone()), mStatus() {}
+
+  CDMKeyInfo(const nsTArray<uint8_t>& aKeyId,
+             const dom::Optional<dom::MediaKeyStatus>& aStatus)
+      : mKeyId(aKeyId.Clone()), mStatus(aStatus.Value()) {}
+
+  // The copy-ctor and copy-assignment operator for Optional<T> are declared as
+  // delete, so override CDMKeyInfo copy-ctor for nsTArray operations.
+  CDMKeyInfo(const CDMKeyInfo& aKeyInfo) {
+    mKeyId = aKeyInfo.mKeyId.Clone();
+    if (aKeyInfo.mStatus.WasPassed()) {
+      mStatus.Construct(aKeyInfo.mStatus.Value());
+    }
+  }
+
+  nsTArray<uint8_t> mKeyId;
+  dom::Optional<dom::MediaKeyStatus> mStatus;
+};
+
+// Time is defined as the number of milliseconds since the
+// Epoch (00:00:00 UTC, January 1, 1970).
+typedef int64_t UnixTime;
+
+// Proxies calls CDM, and proxies calls back.
+// Note: Promises are passed in via a PromiseId, so that the ID can be
+// passed via IPC to the CDM, which can then signal when to reject or
+// resolve the promise using its PromiseId.
+class CDMProxy {
+ protected:
+  typedef dom::PromiseId PromiseId;
+  typedef dom::MediaKeySessionType MediaKeySessionType;
+
+ public:
+  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
+
+  // Main thread only.
+  // Loads the CDM corresponding to mKeySystem.
+  // Calls MediaKeys::OnCDMCreated() when the CDM is created.
+  virtual void Init(PromiseId aPromiseId, const nsAString& aOrigin,
+                    const nsAString& aTopLevelOrigin,
+                    const nsAString& aName) = 0;
+
+  // Main thread only.
+  // Uses the CDM to create a key session.
+  // Calls MediaKeys::OnSessionActivated() when session is created.
+  // Assumes ownership of (std::move()s) aInitData's contents.
+  virtual void CreateSession(uint32_t aCreateSessionToken,
+                             MediaKeySessionType aSessionType,
+                             PromiseId aPromiseId,
+                             const nsAString& aInitDataType,
+                             nsTArray<uint8_t>& aInitData) = 0;
+
+  // Main thread only.
+  // Uses the CDM to load a presistent session stored on disk.
+  // Calls MediaKeys::OnSessionActivated() when session is loaded.
+  virtual void LoadSession(PromiseId aPromiseId,
+                           dom::MediaKeySessionType aSessionType,
+                           const nsAString& aSessionId) = 0;
+
+  // Main thread only.
+  // Sends a new certificate to the CDM.
+  // Calls MediaKeys->ResolvePromise(aPromiseId) after the CDM has
+  // processed the request.
+  // Assumes ownership of (std::move()s) aCert's contents.
+  virtual void SetServerCertificate(PromiseId aPromiseId,
+                                    nsTArray<uint8_t>& aCert) = 0;
+
+  // Main thread only.
+  // Sends an update to the CDM.
+  // Calls MediaKeys->ResolvePromise(aPromiseId) after the CDM has
+  // processed the request.
+  // Assumes ownership of (std::move()s) aResponse's contents.
+  virtual void UpdateSession(const nsAString& aSessionId, PromiseId aPromiseId,
+                             nsTArray<uint8_t>& aResponse) = 0;
+
+  // Main thread only.
+  // Calls MediaKeys->ResolvePromise(aPromiseId) after the CDM has
+  // processed the request.
+  // If processing this operation results in the session actually closing,
+  // we also call MediaKeySession::OnClosed(), which in turn calls
+  // MediaKeys::OnSessionClosed().
+  virtual void CloseSession(const nsAString& aSessionId,
+                            PromiseId aPromiseId) = 0;
+
+  // Main thread only.
+  // Removes all data for a persisent session.
+  // Calls MediaKeys->ResolvePromise(aPromiseId) after the CDM has
+  // processed the request.
+  virtual void RemoveSession(const nsAString& aSessionId,
+                             PromiseId aPromiseId) = 0;
+
+  // Main thread only.
+  // Called to signal a request for output protection information from the CDM.
+  // This should forward the call up the stack where the query should be
+  // performed and then responded to via `NotifyOutputProtectionStatus`.
+  virtual void QueryOutputProtectionStatus() = 0;
+
+  // NotifyOutputProtectionStatus enums. Explicit values are specified to make
+  // it easy to match values in logs.
+  enum class OutputProtectionCheckStatus : uint8_t {
+    CheckFailed = 0,
+    CheckSuccessful = 1,
+  };
+
+  enum class OutputProtectionCaptureStatus : uint8_t {
+    CapturePossilbe = 0,
+    CaptureNotPossible = 1,
+    Unused = 2,
+  };
+  // End NotifyOutputProtectionStatus enums
+
+  // Main thread only.
+  // Notifies this proxy of the protection status for the media the CDM is
+  // associated with. This can be called in response to
+  // `QueryOutputProtectionStatus`, but can also be called without an
+  // associated query. In both cases the information will be forwarded to
+  // the CDM host machinery and used to handle requests from the CDM.
+  // @param aCheckStatus did the check succeed or not.
+  // @param aCaptureStatus if the check succeeded, this reflects if capture
+  // of media could take place. This doesn't mean capture is taking place.
+  // Callers should be conservative with this value such that it's okay to pass
+  // CapturePossilbe even if capture is not happening, but should never pass
+  // CaptureNotPossible if it could happen. If the check failed, this value is
+  // not used, and callers should pass Unused to indicate this.
+  virtual void NotifyOutputProtectionStatus(
+      OutputProtectionCheckStatus aCheckStatus,
+      OutputProtectionCaptureStatus aCaptureStatus) = 0;
+
+  // Main thread only.
+  virtual void Shutdown() = 0;
+
+  // Main thread only.
+  virtual void Terminated() = 0;
+
+  // Threadsafe.
+  const nsCString& GetNodeId() const { return mNodeId; };
+
+  // Main thread only.
+  virtual void OnSetSessionId(uint32_t aCreateSessionToken,
+                              const nsAString& aSessionId) = 0;
+
+  // Main thread only.
+  virtual void OnResolveLoadSessionPromise(uint32_t aPromiseId,
+                                           bool aSuccess) = 0;
+
+  // Main thread only.
+  virtual void OnSessionMessage(const nsAString& aSessionId,
+                                dom::MediaKeyMessageType aMessageType,
+                                const nsTArray<uint8_t>& aMessage) = 0;
+
+  // Main thread only.
+  virtual void OnExpirationChange(const nsAString& aSessionId,
+                                  UnixTime aExpiryTime) = 0;
+
+  // Main thread only.
+  virtual void OnSessionClosed(const nsAString& aSessionId) = 0;
+
+  // Main thread only.
+  virtual void OnSessionError(const nsAString& aSessionId, nsresult aException,
+                              uint32_t aSystemCode, const nsAString& aMsg) = 0;
+
+  // Main thread only.
+  virtual void OnRejectPromise(uint32_t aPromiseId, ErrorResult&& aException,
+                               const nsCString& aMsg) = 0;
+
+  virtual RefPtr<DecryptPromise> Decrypt(MediaRawData* aSample) = 0;
+
+  // Owner thread only.
+  virtual void OnDecrypted(uint32_t aId, DecryptStatus aResult,
+                           const nsTArray<uint8_t>& aDecryptedData) = 0;
+
+  // Reject promise with the given ErrorResult.
+  //
+  // Can be called from any thread.
+  virtual void RejectPromise(PromiseId aId, ErrorResult&& aException,
+                             const nsCString& aReason) = 0;
+
+  // Resolves promise with "undefined".
+  // Can be called from any thread.
+  virtual void ResolvePromise(PromiseId aId) = 0;
+
+  // Threadsafe.
+  const nsString& KeySystem() const { return mKeySystem; };
+
+  DataMutex<CDMCaps>& Capabilites() { return mCapabilites; };
+
+  // Main thread only.
+  virtual void OnKeyStatusesChange(const nsAString& aSessionId) = 0;
+
+  // Main thread only.
+  // Calls MediaKeys->ResolvePromiseWithKeyStatus(aPromiseId, aKeyStatus) after
+  // the CDM has processed the request.
+  virtual void GetStatusForPolicy(PromiseId aPromiseId,
+                                  const nsAString& aMinHdcpVersion) = 0;
+
+#ifdef DEBUG
+  virtual bool IsOnOwnerThread() = 0;
+#endif
+
+  virtual ChromiumCDMProxy* AsChromiumCDMProxy() { return nullptr; }
+
+#ifdef MOZ_WMF_CDM
+  virtual WMFCDMProxy* AsWMFCDMProxy() { return nullptr; }
+#endif
+
+ protected:
+  // Main thread only.
+  CDMProxy(dom::MediaKeys* aKeys, const nsAString& aKeySystem,
+           bool aDistinctiveIdentifierRequired, bool aPersistentStateRequired)
+      : mKeys(aKeys),
+        mKeySystem(aKeySystem),
+        mCapabilites("CDMProxy::mCDMCaps"),
+        mDistinctiveIdentifierRequired(aDistinctiveIdentifierRequired),
+        mPersistentStateRequired(aPersistentStateRequired),
+        mMainThread(GetMainThreadSerialEventTarget()) {
+    MOZ_ASSERT(NS_IsMainThread());
+  }
+
+  virtual ~CDMProxy() {}
+
+  // Helper to enforce that a raw pointer is only accessed on the main thread.
+  template <class Type>
+  class MainThreadOnlyRawPtr {
+   public:
+    explicit MainThreadOnlyRawPtr(Type* aPtr) : mPtr(aPtr) {
+      MOZ_ASSERT(NS_IsMainThread());
+    }
+
+    bool IsNull() const {
+      MOZ_ASSERT(NS_IsMainThread());
+      return !mPtr;
+    }
+
+    void Clear() {
+      MOZ_ASSERT(NS_IsMainThread());
+      mPtr = nullptr;
+    }
+
+    Type* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN {
+      MOZ_ASSERT(NS_IsMainThread());
+      return mPtr;
+    }
+
+   private:
+    Type* mPtr;
+  };
+
+  // Our reference back to the MediaKeys object.
+  // WARNING: This is a non-owning reference that is cleared by MediaKeys
+  // destructor. only use on main thread, and always nullcheck before using!
+  MainThreadOnlyRawPtr<dom::MediaKeys> mKeys;
+
+  const nsString mKeySystem;
+
+  // Onwer specified thread. e.g. Gecko Media Plugin thread.
+  // All interactions with the out-of-process EME plugin must come from this
+  // thread.
+  RefPtr<nsIThread> mOwnerThread;
+
+  nsCString mNodeId;
+
+  DataMutex<CDMCaps> mCapabilites;
+
+  const bool mDistinctiveIdentifierRequired;
+  const bool mPersistentStateRequired;
+
+  // The main thread associated with the root document.
+  const nsCOMPtr<nsISerialEventTarget> mMainThread;
+};
+
+}  // namespace mozilla
+
+#endif  // CDMProxy_h_
diff --git a/dom/media/eme/DecryptorProxyCallback.h b/dom/media/eme/DecryptorProxyCallback.h
new file mode 100644
index 0000000000..88acdd7967
--- /dev/null
+++ b/dom/media/eme/DecryptorProxyCallback.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#ifndef DecryptorProxyCallback_h_
+#define DecryptorProxyCallback_h_
+
+#include "mozilla/dom/MediaKeyStatusMapBinding.h"     // For MediaKeyStatus
+#include "mozilla/dom/MediaKeyMessageEventBinding.h"  // For MediaKeyMessageType
+#include "mozilla/CDMProxy.h"
+
+namespace mozilla {
+class ErrorResult;
+}
+
+class DecryptorProxyCallback {
+ public:
+  virtual ~DecryptorProxyCallback() {}
+
+  virtual void SetSessionId(uint32_t aCreateSessionId,
+                            const nsCString& aSessionId) = 0;
+
+  virtual void ResolveLoadSessionPromise(uint32_t aPromiseId,
+                                         bool aSuccess) = 0;
+
+  virtual void ResolvePromise(uint32_t aPromiseId) = 0;
+
+  virtual void RejectPromise(uint32_t aPromiseId,
+                             mozilla::ErrorResult&& aException,
+                             const nsCString& aSessionId) = 0;
+
+  virtual void SessionMessage(const nsCString& aSessionId,
+                              mozilla::dom::MediaKeyMessageType aMessageType,
+                              const nsTArray<uint8_t>& aMessage) = 0;
+
+  virtual void ExpirationChange(const nsCString& aSessionId,
+                                mozilla::UnixTime aExpiryTime) = 0;
+
+  virtual void SessionClosed(const nsCString& aSessionId) = 0;
+
+  virtual void SessionError(const nsCString& aSessionId, nsresult aException,
+                            uint32_t aSystemCode,
+                            const nsCString& aMessage) = 0;
+
+  virtual void Decrypted(uint32_t aId, mozilla::DecryptStatus aResult,
+                         const nsTArray<uint8_t>& aDecryptedData) = 0;
+
+  virtual void BatchedKeyStatusChanged(
+      const nsCString& aSessionId,
+      const nsTArray<mozilla::CDMKeyInfo>& aKeyInfos) = 0;
+};
+
+#endif
diff --git a/dom/media/eme/DetailedPromise.cpp b/dom/media/eme/DetailedPromise.cpp
new file mode 100644
index 0000000000..0692a1dd07
--- /dev/null
+++ b/dom/media/eme/DetailedPromise.cpp
@@ -0,0 +1,87 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sts=2 et sw=2 tw=80: */
+/* 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 "DetailedPromise.h"
+
+#include "VideoUtils.h"
+#include "mozilla/dom/DOMException.h"
+#include "nsPrintfCString.h"
+
+namespace mozilla::dom {
+
+DetailedPromise::DetailedPromise(nsIGlobalObject* aGlobal,
+                                 const nsACString& aName)
+    : Promise(aGlobal),
+      mName(aName),
+      mResponded(false),
+      mStartTime(TimeStamp::Now()) {}
+
+DetailedPromise::DetailedPromise(nsIGlobalObject* aGlobal,
+                                 const nsACString& aName,
+                                 Telemetry::HistogramID aSuccessLatencyProbe,
+                                 Telemetry::HistogramID aFailureLatencyProbe)
+    : DetailedPromise(aGlobal, aName) {
+  mSuccessLatencyProbe.Construct(aSuccessLatencyProbe);
+  mFailureLatencyProbe.Construct(aFailureLatencyProbe);
+}
+
+DetailedPromise::~DetailedPromise() {
+  // It would be nice to assert that mResponded is identical to
+  // GetPromiseState() == PromiseState::Rejected.  But by now we've been
+  // unlinked, so don't have a reference to our actual JS Promise object
+  // anymore.
+  MaybeReportTelemetry(kFailed);
+}
+
+void DetailedPromise::LogRejectionReason(uint32_t aErrorCode,
+                                         const nsACString& aReason) {
+  nsPrintfCString msg("%s promise rejected 0x%" PRIx32 " '%s'", mName.get(),
+                      aErrorCode, PromiseFlatCString(aReason).get());
+  EME_LOG("%s", msg.get());
+
+  MaybeReportTelemetry(kFailed);
+
+  LogToBrowserConsole(NS_ConvertUTF8toUTF16(msg));
+}
+
+void DetailedPromise::MaybeReject(nsresult aArg, const nsACString& aReason) {
+  LogRejectionReason(static_cast<uint32_t>(aArg), aReason);
+
+  Promise::MaybeRejectWithDOMException(aArg, aReason);
+}
+
+void DetailedPromise::MaybeReject(ErrorResult&& aArg,
+                                  const nsACString& aReason) {
+  LogRejectionReason(aArg.ErrorCodeAsInt(), aReason);
+  Promise::MaybeReject(std::move(aArg));
+}
+
+/* static */
+already_AddRefed<DetailedPromise> DetailedPromise::Create(
+    nsIGlobalObject* aGlobal, ErrorResult& aRv, const nsACString& aName) {
+  RefPtr<DetailedPromise> promise = new DetailedPromise(aGlobal, aName);
+  promise->CreateWrapper(aRv);
+  return aRv.Failed() ? nullptr : promise.forget();
+}
+
+void DetailedPromise::MaybeReportTelemetry(eStatus aStatus) {
+  if (mResponded) {
+    return;
+  }
+  mResponded = true;
+  if (!mSuccessLatencyProbe.WasPassed() || !mFailureLatencyProbe.WasPassed()) {
+    return;
+  }
+  uint32_t latency = (TimeStamp::Now() - mStartTime).ToMilliseconds();
+  EME_LOG("%s %s latency %ums reported via telemetry", mName.get(),
+          ((aStatus == kSucceeded) ? "succcess" : "failure"), latency);
+  Telemetry::HistogramID tid = (aStatus == kSucceeded)
+                                   ? mSuccessLatencyProbe.Value()
+                                   : mFailureLatencyProbe.Value();
+  Telemetry::Accumulate(tid, latency);
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/media/eme/DetailedPromise.h b/dom/media/eme/DetailedPromise.h
new file mode 100644
index 0000000000..02c774755f
--- /dev/null
+++ b/dom/media/eme/DetailedPromise.h
@@ -0,0 +1,104 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef __DetailedPromise_h__
+#define __DetailedPromise_h__
+
+#include "mozilla/dom/Promise.h"
+#include "mozilla/Telemetry.h"
+#include "EMEUtils.h"
+
+namespace mozilla::dom {
+
+/*
+ * This is pretty horrible; bug 1160445.
+ * Extend Promise to add custom DOMException messages on rejection.
+ * Get rid of this once we've ironed out EME errors in the wild.
+ */
+class DetailedPromise : public Promise {
+ public:
+  static already_AddRefed<DetailedPromise> Create(nsIGlobalObject* aGlobal,
+                                                  ErrorResult& aRv,
+                                                  const nsACString& aName);
+
+  template <typename T>
+  void MaybeResolve(T&& aArg) {
+    EME_LOG("%s promise resolved", mName.get());
+    MaybeReportTelemetry(eStatus::kSucceeded);
+    Promise::MaybeResolve(std::forward<T>(aArg));
+  }
+
+  void MaybeReject(nsresult aArg) = delete;
+  void MaybeReject(nsresult aArg, const nsACString& aReason);
+
+  void MaybeReject(ErrorResult&& aArg) = delete;
+  void MaybeReject(ErrorResult&& aArg, const nsACString& aReason);
+
+  // Facilities for rejecting with various spec-defined exception values.
+#define DOMEXCEPTION(name, err)                                   \
+  inline void MaybeRejectWith##name(const nsACString& aMessage) { \
+    LogRejectionReason(static_cast<uint32_t>(err), aMessage);     \
+    Promise::MaybeRejectWith##name(aMessage);                     \
+  }                                                               \
+  template <int N>                                                \
+  void MaybeRejectWith##name(const char(&aMessage)[N]) {          \
+    MaybeRejectWith##name(nsLiteralCString(aMessage));            \
+  }
+
+#include "mozilla/dom/DOMExceptionNames.h"
+
+#undef DOMEXCEPTION
+
+  template <ErrNum errorNumber, typename... Ts>
+  void MaybeRejectWithTypeError(Ts&&... aMessageArgs) = delete;
+
+  inline void MaybeRejectWithTypeError(const nsACString& aMessage) {
+    ErrorResult res;
+    res.ThrowTypeError(aMessage);
+    MaybeReject(std::move(res), aMessage);
+  }
+
+  template <int N>
+  void MaybeRejectWithTypeError(const char (&aMessage)[N]) {
+    MaybeRejectWithTypeError(nsLiteralCString(aMessage));
+  }
+
+  template <ErrNum errorNumber, typename... Ts>
+  void MaybeRejectWithRangeError(Ts&&... aMessageArgs) = delete;
+
+  inline void MaybeRejectWithRangeError(const nsACString& aMessage) {
+    ErrorResult res;
+    res.ThrowRangeError(aMessage);
+    MaybeReject(std::move(res), aMessage);
+  }
+
+  template <int N>
+  void MaybeRejectWithRangeError(const char (&aMessage)[N]) {
+    MaybeRejectWithRangeError(nsLiteralCString(aMessage));
+  }
+
+ private:
+  explicit DetailedPromise(nsIGlobalObject* aGlobal, const nsACString& aName);
+
+  explicit DetailedPromise(nsIGlobalObject* aGlobal, const nsACString& aName,
+                           Telemetry::HistogramID aSuccessLatencyProbe,
+                           Telemetry::HistogramID aFailureLatencyProbe);
+  virtual ~DetailedPromise();
+
+  enum eStatus { kSucceeded, kFailed };
+  void MaybeReportTelemetry(eStatus aStatus);
+  void LogRejectionReason(uint32_t aErrorCode, const nsACString& aReason);
+
+  nsCString mName;
+  bool mResponded;
+  TimeStamp mStartTime;
+  Optional<Telemetry::HistogramID> mSuccessLatencyProbe;
+  Optional<Telemetry::HistogramID> mFailureLatencyProbe;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // __DetailedPromise_h__
diff --git a/dom/media/eme/EMEUtils.cpp b/dom/media/eme/EMEUtils.cpp
new file mode 100644
index 0000000000..0f1630589e
--- /dev/null
+++ b/dom/media/eme/EMEUtils.cpp
@@ -0,0 +1,119 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/EMEUtils.h"
+
+#include "jsfriendapi.h"
+#include "mozilla/StaticPrefs_media.h"
+#include "mozilla/dom/KeySystemNames.h"
+#include "mozilla/dom/UnionTypes.h"
+
+namespace mozilla {
+
+LogModule* GetEMELog() {
+  static LazyLogModule log("EME");
+  return log;
+}
+
+LogModule* GetEMEVerboseLog() {
+  static LazyLogModule log("EMEV");
+  return log;
+}
+
+ArrayData GetArrayBufferViewOrArrayBufferData(
+    const dom::ArrayBufferViewOrArrayBuffer& aBufferOrView) {
+  MOZ_ASSERT(aBufferOrView.IsArrayBuffer() ||
+             aBufferOrView.IsArrayBufferView());
+  JS::AutoCheckCannotGC nogc;
+  if (aBufferOrView.IsArrayBuffer()) {
+    const dom::ArrayBuffer& buffer = aBufferOrView.GetAsArrayBuffer();
+    buffer.ComputeState();
+    return ArrayData(buffer.Data(), buffer.Length());
+  } else if (aBufferOrView.IsArrayBufferView()) {
+    const dom::ArrayBufferView& bufferview =
+        aBufferOrView.GetAsArrayBufferView();
+    bufferview.ComputeState();
+    return ArrayData(bufferview.Data(), bufferview.Length());
+  }
+  return ArrayData(nullptr, 0);
+}
+
+void CopyArrayBufferViewOrArrayBufferData(
+    const dom::ArrayBufferViewOrArrayBuffer& aBufferOrView,
+    nsTArray<uint8_t>& aOutData) {
+  JS::AutoCheckCannotGC nogc;
+  ArrayData data = GetArrayBufferViewOrArrayBufferData(aBufferOrView);
+  aOutData.Clear();
+  if (!data.IsValid()) {
+    return;
+  }
+  aOutData.AppendElements(data.mData, data.mLength);
+}
+
+bool IsClearkeyKeySystem(const nsAString& aKeySystem) {
+  if (StaticPrefs::media_clearkey_test_key_systems_enabled()) {
+    return aKeySystem.EqualsLiteral(kClearKeyKeySystemName) ||
+           aKeySystem.EqualsLiteral(kClearKeyWithProtectionQueryKeySystemName);
+  }
+  return aKeySystem.EqualsLiteral(kClearKeyKeySystemName);
+}
+
+bool IsWidevineKeySystem(const nsAString& aKeySystem) {
+  return aKeySystem.EqualsLiteral(kWidevineKeySystemName);
+}
+
+#ifdef MOZ_WMF_CDM
+bool IsPlayReadyKeySystemAndSupported(const nsAString& aKeySystem) {
+  if (!StaticPrefs::media_eme_playready_enabled()) {
+    return false;
+  }
+  // 1=enabled encrypted and clear, 2=enabled encrytped.
+  if (StaticPrefs::media_wmf_media_engine_enabled() != 1 &&
+      StaticPrefs::media_wmf_media_engine_enabled() != 2) {
+    return false;
+  }
+  return aKeySystem.EqualsLiteral(kPlayReadyKeySystemName) ||
+         aKeySystem.EqualsLiteral(kPlayReadyKeySystemHardware);
+}
+#endif
+
+nsString KeySystemToProxyName(const nsAString& aKeySystem) {
+  if (IsClearkeyKeySystem(aKeySystem)) {
+    return u"gmp-clearkey"_ns;
+  }
+  if (IsWidevineKeySystem(aKeySystem)) {
+    return u"gmp-widevinecdm"_ns;
+  }
+#ifdef MOZ_WMF_CDM
+  if (IsPlayReadyKeySystemAndSupported(aKeySystem)) {
+    return u"mfcdm-playready"_ns;
+  }
+#endif
+  MOZ_ASSERT_UNREACHABLE("Not supported key system!");
+  return u""_ns;
+}
+
+#define ENUM_TO_STR(enumVal) \
+  case enumVal:              \
+    return #enumVal
+
+const char* ToMediaKeyStatusStr(dom::MediaKeyStatus aStatus) {
+  switch (aStatus) {
+    ENUM_TO_STR(dom::MediaKeyStatus::Usable);
+    ENUM_TO_STR(dom::MediaKeyStatus::Expired);
+    ENUM_TO_STR(dom::MediaKeyStatus::Released);
+    ENUM_TO_STR(dom::MediaKeyStatus::Output_restricted);
+    ENUM_TO_STR(dom::MediaKeyStatus::Output_downscaled);
+    ENUM_TO_STR(dom::MediaKeyStatus::Status_pending);
+    ENUM_TO_STR(dom::MediaKeyStatus::Internal_error);
+    default:
+      return "Undefined MediaKeyStatus!";
+  }
+}
+
+#undef ENUM_TO_STR
+
+}  // namespace mozilla
diff --git a/dom/media/eme/EMEUtils.h b/dom/media/eme/EMEUtils.h
new file mode 100644
index 0000000000..2a9af09d58
--- /dev/null
+++ b/dom/media/eme/EMEUtils.h
@@ -0,0 +1,106 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef EME_LOG_H_
+#define EME_LOG_H_
+
+#include "mozilla/Logging.h"
+#include "mozilla/dom/MediaKeyStatusMapBinding.h"
+#include "nsString.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+
+namespace dom {
+class ArrayBufferViewOrArrayBuffer;
+}
+
+#ifndef EME_LOG
+LogModule* GetEMELog();
+#  define EME_LOG(...) \
+    MOZ_LOG(GetEMELog(), mozilla::LogLevel::Debug, (__VA_ARGS__))
+#  define EME_LOG_ENABLED() MOZ_LOG_TEST(GetEMELog(), mozilla::LogLevel::Debug)
+#endif
+
+#ifndef EME_VERBOSE_LOG
+LogModule* GetEMEVerboseLog();
+#  define EME_VERBOSE_LOG(...) \
+    MOZ_LOG(GetEMEVerboseLog(), mozilla::LogLevel::Debug, (__VA_ARGS__))
+#else
+#  ifndef EME_LOG
+#    define EME_LOG(...)
+#  endif
+
+#  ifndef EME_VERBOSE_LOG
+#    define EME_VERBOSE_LOG(...)
+#  endif
+#endif
+
+// Helper function to extract a copy of data coming in from JS in an
+// (ArrayBuffer or ArrayBufferView) IDL typed function argument.
+//
+// Only call this on a properly initialized ArrayBufferViewOrArrayBuffer.
+void CopyArrayBufferViewOrArrayBufferData(
+    const dom::ArrayBufferViewOrArrayBuffer& aBufferOrView,
+    nsTArray<uint8_t>& aOutData);
+
+struct ArrayData {
+  explicit ArrayData(const uint8_t* aData, size_t aLength)
+      : mData(aData), mLength(aLength) {}
+  const uint8_t* mData;
+  const size_t mLength;
+  bool IsValid() const { return mData != nullptr && mLength != 0; }
+  bool operator==(const nsTArray<uint8_t>& aOther) const {
+    return mLength == aOther.Length() &&
+           memcmp(mData, aOther.Elements(), mLength) == 0;
+  }
+};
+
+// Helper function to extract data coming in from JS in an
+// (ArrayBuffer or ArrayBufferView) IDL typed function argument.
+//
+// Be *very* careful with this!
+//
+// Only use returned ArrayData inside the lifetime of the
+// ArrayBufferViewOrArrayBuffer; the ArrayData struct does not contain
+// a copy of the data!
+//
+// And do *not* call out to anything that could call into JavaScript,
+// while the ArrayData is live, as then all bets about the data not changing
+// are off! No calls into JS, no calls into JS-implemented WebIDL or XPIDL,
+// nothing. Beware!
+//
+// Only call this on a properly initialized ArrayBufferViewOrArrayBuffer.
+ArrayData GetArrayBufferViewOrArrayBufferData(
+    const dom::ArrayBufferViewOrArrayBuffer& aBufferOrView);
+
+nsString KeySystemToProxyName(const nsAString& aKeySystem);
+
+bool IsClearkeyKeySystem(const nsAString& aKeySystem);
+
+bool IsWidevineKeySystem(const nsAString& aKeySystem);
+
+#ifdef MOZ_WMF_CDM
+bool IsPlayReadyKeySystemAndSupported(const nsAString& aKeySystem);
+#endif
+
+// Note: Primetime is now unsupported, but we leave it in the enum so
+// that the telemetry enum values are not changed; doing so would break
+// existing telemetry probes.
+enum CDMType {
+  eClearKey = 0,
+  ePrimetime = 1,  // Note: Unsupported.
+  eWidevine = 2,
+  eUnknown = 3
+};
+
+CDMType ToCDMTypeTelemetryEnum(const nsString& aKeySystem);
+
+const char* ToMediaKeyStatusStr(dom::MediaKeyStatus aStatus);
+
+}  // namespace mozilla
+
+#endif  // EME_LOG_H_
diff --git a/dom/media/eme/KeySystemConfig.cpp b/dom/media/eme/KeySystemConfig.cpp
new file mode 100644
index 0000000000..b8eacc7f9d
--- /dev/null
+++ b/dom/media/eme/KeySystemConfig.cpp
@@ -0,0 +1,213 @@
+/* -*- 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 "KeySystemConfig.h"
+
+#include "EMEUtils.h"
+#include "GMPUtils.h"
+#include "KeySystemNames.h"
+#include "mozilla/StaticPrefs_media.h"
+
+#ifdef XP_WIN
+#  include "WMFDecoderModule.h"
+#endif
+#ifdef MOZ_WIDGET_ANDROID
+#  include "AndroidDecoderModule.h"
+#  include "mozilla/java/MediaDrmProxyWrappers.h"
+#  include "nsMimeTypes.h"
+#endif
+
+#ifdef MOZ_WMF_CDM
+#  include "mediafoundation/WMFCDMImpl.h"
+#endif
+
+namespace mozilla {
+
+/* static */
+bool KeySystemConfig::Supports(const nsAString& aKeySystem) {
+  nsCString api = nsLiteralCString(CHROMIUM_CDM_API);
+  nsCString name = NS_ConvertUTF16toUTF8(aKeySystem);
+
+  if (HaveGMPFor(api, {name})) {
+    return true;
+  }
+#ifdef MOZ_WIDGET_ANDROID
+  // Check if we can use MediaDrm for this keysystem.
+  if (mozilla::java::MediaDrmProxy::IsSchemeSupported(name)) {
+    return true;
+  }
+#endif
+#if MOZ_WMF_CDM
+  if (IsPlayReadyKeySystemAndSupported(aKeySystem) &&
+      WMFCDMImpl::Supports(aKeySystem)) {
+    return true;
+  }
+#endif
+  return false;
+}
+
+/* static */
+bool KeySystemConfig::GetConfig(const nsAString& aKeySystem,
+                                KeySystemConfig& aConfig) {
+  if (!Supports(aKeySystem)) {
+    return false;
+  }
+
+  if (IsClearkeyKeySystem(aKeySystem)) {
+    aConfig.mKeySystem = aKeySystem;
+    aConfig.mInitDataTypes.AppendElement(u"cenc"_ns);
+    aConfig.mInitDataTypes.AppendElement(u"keyids"_ns);
+    aConfig.mInitDataTypes.AppendElement(u"webm"_ns);
+    aConfig.mPersistentState = Requirement::Optional;
+    aConfig.mDistinctiveIdentifier = Requirement::NotAllowed;
+    aConfig.mSessionTypes.AppendElement(SessionType::Temporary);
+    aConfig.mEncryptionSchemes.AppendElement(u"cenc"_ns);
+    aConfig.mEncryptionSchemes.AppendElement(u"cbcs"_ns);
+    aConfig.mEncryptionSchemes.AppendElement(u"cbcs-1-9"_ns);
+    if (StaticPrefs::media_clearkey_persistent_license_enabled()) {
+      aConfig.mSessionTypes.AppendElement(SessionType::PersistentLicense);
+    }
+#if defined(XP_WIN)
+    // Clearkey CDM uses WMF's H.264 decoder on Windows.
+    if (WMFDecoderModule::CanCreateMFTDecoder(WMFStreamType::H264)) {
+      aConfig.mMP4.SetCanDecryptAndDecode(EME_CODEC_H264);
+    } else {
+      aConfig.mMP4.SetCanDecrypt(EME_CODEC_H264);
+    }
+#else
+    aConfig.mMP4.SetCanDecrypt(EME_CODEC_H264);
+#endif
+    aConfig.mMP4.SetCanDecrypt(EME_CODEC_AAC);
+    aConfig.mMP4.SetCanDecrypt(EME_CODEC_FLAC);
+    aConfig.mMP4.SetCanDecrypt(EME_CODEC_OPUS);
+    aConfig.mMP4.SetCanDecrypt(EME_CODEC_VP9);
+    aConfig.mWebM.SetCanDecrypt(EME_CODEC_VORBIS);
+    aConfig.mWebM.SetCanDecrypt(EME_CODEC_OPUS);
+    aConfig.mWebM.SetCanDecrypt(EME_CODEC_VP8);
+    aConfig.mWebM.SetCanDecrypt(EME_CODEC_VP9);
+    return true;
+  }
+  if (IsWidevineKeySystem(aKeySystem)) {
+    aConfig.mKeySystem = aKeySystem;
+    aConfig.mInitDataTypes.AppendElement(u"cenc"_ns);
+    aConfig.mInitDataTypes.AppendElement(u"keyids"_ns);
+    aConfig.mInitDataTypes.AppendElement(u"webm"_ns);
+    aConfig.mPersistentState = Requirement::Optional;
+    aConfig.mDistinctiveIdentifier = Requirement::NotAllowed;
+    aConfig.mSessionTypes.AppendElement(SessionType::Temporary);
+#ifdef MOZ_WIDGET_ANDROID
+    aConfig.mSessionTypes.AppendElement(SessionType::PersistentLicense);
+#endif
+    aConfig.mAudioRobustness.AppendElement(u"SW_SECURE_CRYPTO"_ns);
+    aConfig.mVideoRobustness.AppendElement(u"SW_SECURE_CRYPTO"_ns);
+    aConfig.mVideoRobustness.AppendElement(u"SW_SECURE_DECODE"_ns);
+    aConfig.mEncryptionSchemes.AppendElement(u"cenc"_ns);
+    aConfig.mEncryptionSchemes.AppendElement(u"cbcs"_ns);
+    aConfig.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;
+      KeySystemConfig::ContainerSupport* mSupportType;
+    } DataForValidation;
+
+    DataForValidation validationList[] = {
+        {nsCString(VIDEO_MP4), EME_CODEC_H264, java::MediaDrmProxy::AVC,
+         &aConfig.mMP4},
+        {nsCString(VIDEO_MP4), EME_CODEC_VP9, java::MediaDrmProxy::AVC,
+         &aConfig.mMP4},
+        {nsCString(AUDIO_MP4), EME_CODEC_AAC, java::MediaDrmProxy::AAC,
+         &aConfig.mMP4},
+        {nsCString(AUDIO_MP4), EME_CODEC_FLAC, java::MediaDrmProxy::FLAC,
+         &aConfig.mMP4},
+        {nsCString(AUDIO_MP4), EME_CODEC_OPUS, java::MediaDrmProxy::OPUS,
+         &aConfig.mMP4},
+        {nsCString(VIDEO_WEBM), EME_CODEC_VP8, java::MediaDrmProxy::VP8,
+         &aConfig.mWebM},
+        {nsCString(VIDEO_WEBM), EME_CODEC_VP9, java::MediaDrmProxy::VP9,
+         &aConfig.mWebM},
+        {nsCString(AUDIO_WEBM), EME_CODEC_VORBIS, java::MediaDrmProxy::VORBIS,
+         &aConfig.mWebM},
+        {nsCString(AUDIO_WEBM), EME_CODEC_OPUS, java::MediaDrmProxy::OPUS,
+         &aConfig.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)) {
+      aConfig.mMP4.SetCanDecrypt(EME_CODEC_AAC);
+    }
+#  else
+    aConfig.mMP4.SetCanDecrypt(EME_CODEC_AAC);
+#  endif
+    aConfig.mMP4.SetCanDecrypt(EME_CODEC_FLAC);
+    aConfig.mMP4.SetCanDecrypt(EME_CODEC_OPUS);
+    aConfig.mMP4.SetCanDecryptAndDecode(EME_CODEC_H264);
+    aConfig.mMP4.SetCanDecryptAndDecode(EME_CODEC_VP9);
+    aConfig.mWebM.SetCanDecrypt(EME_CODEC_VORBIS);
+    aConfig.mWebM.SetCanDecrypt(EME_CODEC_OPUS);
+    aConfig.mWebM.SetCanDecryptAndDecode(EME_CODEC_VP8);
+    aConfig.mWebM.SetCanDecryptAndDecode(EME_CODEC_VP9);
+#endif
+    return true;
+  }
+#ifdef MOZ_WMF_CDM
+  if (IsPlayReadyKeySystemAndSupported(aKeySystem)) {
+    RefPtr<WMFCDMImpl> cdm = MakeRefPtr<WMFCDMImpl>(aKeySystem);
+    return cdm->GetCapabilities(aConfig);
+  }
+#endif
+  return false;
+}
+
+KeySystemConfig::SessionType ConvertToKeySystemConfigSessionType(
+    dom::MediaKeySessionType aType) {
+  switch (aType) {
+    case dom::MediaKeySessionType::Temporary:
+      return KeySystemConfig::SessionType::Temporary;
+    case dom::MediaKeySessionType::Persistent_license:
+      return KeySystemConfig::SessionType::PersistentLicense;
+    default:
+      MOZ_ASSERT_UNREACHABLE("Invalid session type");
+      return KeySystemConfig::SessionType::Temporary;
+  }
+}
+
+const char* SessionTypeToStr(KeySystemConfig::SessionType aType) {
+  switch (aType) {
+    case KeySystemConfig::SessionType::Temporary:
+      return "Temporary";
+    case KeySystemConfig::SessionType::PersistentLicense:
+      return "PersistentLicense";
+    default:
+      MOZ_ASSERT_UNREACHABLE("Invalid session type");
+      return "Invalid";
+  }
+}
+
+}  // namespace mozilla
diff --git a/dom/media/eme/KeySystemConfig.h b/dom/media/eme/KeySystemConfig.h
new file mode 100644
index 0000000000..bf813b44e9
--- /dev/null
+++ b/dom/media/eme/KeySystemConfig.h
@@ -0,0 +1,157 @@
+/* -*- 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/. */
+
+#ifndef DOM_MEDIA_EME_KEYSYSTEMCONFIG_H_
+#define DOM_MEDIA_EME_KEYSYSTEMCONFIG_H_
+
+#include "nsString.h"
+#include "nsTArray.h"
+#include "mozilla/dom/MediaKeysBinding.h"
+
+namespace mozilla {
+
+struct KeySystemConfig {
+ public:
+  // EME MediaKeysRequirement:
+  // https://www.w3.org/TR/encrypted-media/#dom-mediakeysrequirement
+  enum class Requirement {
+    Required = 1,
+    Optional = 2,
+    NotAllowed = 3,
+  };
+
+  // EME MediaKeySessionType:
+  // https://www.w3.org/TR/encrypted-media/#dom-mediakeysessiontype
+  enum class SessionType {
+    Temporary = 1,
+    PersistentLicense = 2,
+  };
+
+  using EMECodecString = nsCString;
+  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;
+
+  using EMEEncryptionSchemeString = nsCString;
+  static constexpr auto EME_ENCRYPTION_SCHEME_CENC = "cenc"_ns;
+  static constexpr auto EME_ENCRYPTION_SCHEME_CBCS = "cbcs"_ns;
+
+  // A codec can be decrypted-and-decoded by the CDM, or only decrypted
+  // by the CDM and decoded by Gecko. Not both.
+  struct ContainerSupport {
+    ContainerSupport() = default;
+    ~ContainerSupport() = default;
+    ContainerSupport(const ContainerSupport& aOther) {
+      mCodecsDecoded = aOther.mCodecsDecoded.Clone();
+      mCodecsDecrypted = aOther.mCodecsDecrypted.Clone();
+    }
+    ContainerSupport& operator=(const ContainerSupport& aOther) {
+      if (this == &aOther) {
+        return *this;
+      }
+      mCodecsDecoded = aOther.mCodecsDecoded.Clone();
+      mCodecsDecrypted = aOther.mCodecsDecrypted.Clone();
+      return *this;
+    }
+    ContainerSupport(ContainerSupport&& aOther) = default;
+    ContainerSupport& operator=(ContainerSupport&&) = 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(const EMECodecString& aCodec) const {
+      return mCodecsDecoded.Contains(aCodec);
+    }
+
+    // CDM decrypts and passes the decrypted samples back to Gecko for decoding.
+    bool Decrypts(const EMECodecString& aCodec) const {
+      return mCodecsDecrypted.Contains(aCodec);
+    }
+
+    void SetCanDecryptAndDecode(const 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(const 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;
+  };
+
+  static bool Supports(const nsAString& aKeySystem);
+  static bool GetConfig(const nsAString& aKeySystem, KeySystemConfig& aConfig);
+
+  KeySystemConfig() = default;
+  ~KeySystemConfig() = default;
+  explicit 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;
+  Requirement mPersistentState = Requirement::NotAllowed;
+  Requirement mDistinctiveIdentifier = Requirement::NotAllowed;
+  nsTArray<SessionType> mSessionTypes;
+  nsTArray<nsString> mVideoRobustness;
+  nsTArray<nsString> mAudioRobustness;
+  nsTArray<nsString> mEncryptionSchemes;
+  ContainerSupport mMP4;
+  ContainerSupport mWebM;
+  bool mIsHW = false;
+};
+
+KeySystemConfig::SessionType ConvertToKeySystemConfigSessionType(
+    dom::MediaKeySessionType aType);
+const char* SessionTypeToStr(KeySystemConfig::SessionType aType);
+
+}  // namespace mozilla
+
+#endif  // DOM_MEDIA_EME_KEYSYSTEMCONFIG_H_
diff --git a/dom/media/eme/KeySystemNames.h b/dom/media/eme/KeySystemNames.h
new file mode 100644
index 0000000000..24b59f5d8e
--- /dev/null
+++ b/dom/media/eme/KeySystemNames.h
@@ -0,0 +1,33 @@
+/* -*- 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/. */
+
+#ifndef DOM_MEDIA_EME_KEY_SYSTEM_NAMES_H_
+#define DOM_MEDIA_EME_KEY_SYSTEM_NAMES_H_
+
+// Header for key system names. Keep these separate from some of our other
+// EME utils because want to use these strings in contexts where other utils
+// may not build correctly. Specifically at time of writing:
+// - The GMP doesn't have prefs available, so we want to avoid utils that
+//   touch the pref service.
+// - The clear key CDM links a limited subset of what normal Fx does, so we
+//   need to avoid any utils that touch things like XUL.
+
+namespace mozilla {
+// EME Key System Strings.
+inline constexpr char kClearKeyKeySystemName[] = "org.w3.clearkey";
+inline constexpr char kClearKeyWithProtectionQueryKeySystemName[] =
+    "org.mozilla.clearkey_with_protection_query";
+inline constexpr char kWidevineKeySystemName[] = "com.widevine.alpha";
+#ifdef MOZ_WMF_CDM
+// https://learn.microsoft.com/en-us/playready/overview/key-system-strings
+inline constexpr char kPlayReadyKeySystemName[] =
+    "com.microsoft.playready.recommendation";
+inline constexpr char kPlayReadyKeySystemHardware[] =
+    "com.microsoft.playready.recommendation.3000";
+#endif
+}  // namespace mozilla
+
+#endif  // DOM_MEDIA_EME_KEY_SYSTEM_NAMES_H_
diff --git a/dom/media/eme/MediaEncryptedEvent.cpp b/dom/media/eme/MediaEncryptedEvent.cpp
new file mode 100644
index 0000000000..b011715295
--- /dev/null
+++ b/dom/media/eme/MediaEncryptedEvent.cpp
@@ -0,0 +1,108 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 "MediaEncryptedEvent.h"
+#include "mozilla/dom/MediaEncryptedEventBinding.h"
+#include "nsContentUtils.h"
+#include "js/ArrayBuffer.h"
+#include "jsfriendapi.h"
+#include "nsINode.h"
+#include "mozilla/dom/MediaKeys.h"
+#include "mozilla/HoldDropJSObjects.h"
+
+namespace mozilla::dom {
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(MediaEncryptedEvent)
+
+NS_IMPL_ADDREF_INHERITED(MediaEncryptedEvent, Event)
+NS_IMPL_RELEASE_INHERITED(MediaEncryptedEvent, Event)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(MediaEncryptedEvent, Event)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(MediaEncryptedEvent, Event)
+  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mInitData)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(MediaEncryptedEvent, Event)
+  mozilla::DropJSObjects(tmp);
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MediaEncryptedEvent)
+NS_INTERFACE_MAP_END_INHERITING(Event)
+
+MediaEncryptedEvent::MediaEncryptedEvent(EventTarget* aOwner)
+    : Event(aOwner, nullptr, nullptr) {
+  mozilla::HoldJSObjects(this);
+}
+
+MediaEncryptedEvent::~MediaEncryptedEvent() { mozilla::DropJSObjects(this); }
+
+JSObject* MediaEncryptedEvent::WrapObjectInternal(
+    JSContext* aCx, JS::Handle<JSObject*> aGivenProto) {
+  return MediaEncryptedEvent_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+already_AddRefed<MediaEncryptedEvent> MediaEncryptedEvent::Constructor(
+    EventTarget* aOwner) {
+  RefPtr<MediaEncryptedEvent> e = new MediaEncryptedEvent(aOwner);
+  e->InitEvent(u"encrypted"_ns, CanBubble::eNo, Cancelable::eNo);
+  e->SetTrusted(true);
+  return e.forget();
+}
+
+already_AddRefed<MediaEncryptedEvent> MediaEncryptedEvent::Constructor(
+    EventTarget* aOwner, const nsAString& aInitDataType,
+    const nsTArray<uint8_t>& aInitData) {
+  RefPtr<MediaEncryptedEvent> e = new MediaEncryptedEvent(aOwner);
+  e->InitEvent(u"encrypted"_ns, CanBubble::eNo, Cancelable::eNo);
+  e->mInitDataType = aInitDataType;
+  e->mRawInitData = aInitData.Clone();
+  e->SetTrusted(true);
+  return e.forget();
+}
+
+already_AddRefed<MediaEncryptedEvent> MediaEncryptedEvent::Constructor(
+    const GlobalObject& aGlobal, const nsAString& aType,
+    const MediaKeyNeededEventInit& aEventInitDict, ErrorResult& aRv) {
+  nsCOMPtr<EventTarget> owner = do_QueryInterface(aGlobal.GetAsSupports());
+  RefPtr<MediaEncryptedEvent> e = new MediaEncryptedEvent(owner);
+  bool trusted = e->Init(owner);
+  e->InitEvent(aType, aEventInitDict.mBubbles, aEventInitDict.mCancelable);
+  e->mInitDataType = aEventInitDict.mInitDataType;
+  if (!aEventInitDict.mInitData.IsNull()) {
+    JS::Rooted<JSObject*> buffer(aGlobal.Context(),
+                                 aEventInitDict.mInitData.Value().Obj());
+    e->mInitData = JS::CopyArrayBuffer(aGlobal.Context(), buffer);
+    if (!e->mInitData) {
+      aRv.NoteJSContextException(aGlobal.Context());
+      return nullptr;
+    }
+  }
+  e->SetTrusted(trusted);
+  return e.forget();
+}
+
+void MediaEncryptedEvent::GetInitDataType(nsString& aRetVal) const {
+  aRetVal = mInitDataType;
+}
+
+void MediaEncryptedEvent::GetInitData(JSContext* cx,
+                                      JS::MutableHandle<JSObject*> aData,
+                                      ErrorResult& aRv) {
+  if (mRawInitData.Length()) {
+    mInitData = ArrayBuffer::Create(cx, this, mRawInitData.Length(),
+                                    mRawInitData.Elements());
+    if (!mInitData) {
+      aRv.NoteJSContextException(cx);
+      return;
+    }
+    mRawInitData.Clear();
+  }
+  aData.set(mInitData);
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/media/eme/MediaEncryptedEvent.h b/dom/media/eme/MediaEncryptedEvent.h
new file mode 100644
index 0000000000..0fcb5db051
--- /dev/null
+++ b/dom/media/eme/MediaEncryptedEvent.h
@@ -0,0 +1,60 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef mozilla_dom_MediaKeyNeededEvent_h__
+#define mozilla_dom_MediaKeyNeededEvent_h__
+
+#include <cstdint>
+#include "js/RootingAPI.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/dom/Event.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsISupports.h"
+#include "nsStringFwd.h"
+#include "nsTArray.h"
+
+namespace mozilla::dom {
+struct MediaKeyNeededEventInit;
+
+class MediaEncryptedEvent final : public Event {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(MediaEncryptedEvent,
+                                                         Event)
+ protected:
+  virtual ~MediaEncryptedEvent();
+  explicit MediaEncryptedEvent(EventTarget* aOwner);
+
+  nsString mInitDataType;
+  JS::Heap<JSObject*> mInitData;
+
+ public:
+  JSObject* WrapObjectInternal(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+
+  static already_AddRefed<MediaEncryptedEvent> Constructor(EventTarget* aOwner);
+
+  static already_AddRefed<MediaEncryptedEvent> Constructor(
+      EventTarget* aOwner, const nsAString& aInitDataType,
+      const nsTArray<uint8_t>& aInitData);
+
+  static already_AddRefed<MediaEncryptedEvent> Constructor(
+      const GlobalObject& aGlobal, const nsAString& aType,
+      const MediaKeyNeededEventInit& aEventInitDict, ErrorResult& aRv);
+
+  void GetInitDataType(nsString& aRetVal) const;
+
+  void GetInitData(JSContext* cx, JS::MutableHandle<JSObject*> aData,
+                   ErrorResult& aRv);
+
+ private:
+  nsTArray<uint8_t> mRawInitData;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_MediaKeyNeededEvent_h__
diff --git a/dom/media/eme/MediaKeyError.cpp b/dom/media/eme/MediaKeyError.cpp
new file mode 100644
index 0000000000..7172b0d05b
--- /dev/null
+++ b/dom/media/eme/MediaKeyError.cpp
@@ -0,0 +1,27 @@
+/* -*- 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 "MediaKeyError.h"
+#include "mozilla/dom/MediaKeyErrorBinding.h"
+#include "nsContentUtils.h"
+
+namespace mozilla::dom {
+
+MediaKeyError::MediaKeyError(EventTarget* aOwner, uint32_t aSystemCode)
+    : Event(aOwner, nullptr, nullptr), mSystemCode(aSystemCode) {
+  InitEvent(u"error"_ns, CanBubble::eNo, Cancelable::eNo);
+}
+
+MediaKeyError::~MediaKeyError() = default;
+
+uint32_t MediaKeyError::SystemCode() const { return mSystemCode; }
+
+JSObject* MediaKeyError::WrapObjectInternal(JSContext* aCx,
+                                            JS::Handle<JSObject*> aGivenProto) {
+  return MediaKeyError_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/media/eme/MediaKeyError.h b/dom/media/eme/MediaKeyError.h
new file mode 100644
index 0000000000..ef4ecf1375
--- /dev/null
+++ b/dom/media/eme/MediaKeyError.h
@@ -0,0 +1,33 @@
+/* -*- 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/. */
+
+#ifndef mozilla_dom_MediaKeyError_h
+#define mozilla_dom_MediaKeyError_h
+
+#include "mozilla/Attributes.h"
+#include "nsWrapperCache.h"
+#include "mozilla/dom/Event.h"
+#include "js/TypeDecls.h"
+
+namespace mozilla::dom {
+
+class MediaKeyError final : public Event {
+ public:
+  MediaKeyError(EventTarget* aOwner, uint32_t aSystemCode);
+  ~MediaKeyError();
+
+  JSObject* WrapObjectInternal(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+
+  uint32_t SystemCode() const;
+
+ private:
+  uint32_t mSystemCode;
+};
+
+}  // namespace mozilla::dom
+
+#endif
diff --git a/dom/media/eme/MediaKeyMessageEvent.cpp b/dom/media/eme/MediaKeyMessageEvent.cpp
new file mode 100644
index 0000000000..69ce5499f4
--- /dev/null
+++ b/dom/media/eme/MediaKeyMessageEvent.cpp
@@ -0,0 +1,103 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/MediaKeyMessageEvent.h"
+#include "mozilla/dom/MediaKeyMessageEventBinding.h"
+#include "js/ArrayBuffer.h"
+#include "js/RootingAPI.h"
+#include "jsfriendapi.h"
+#include "mozilla/dom/Nullable.h"
+#include "mozilla/dom/PrimitiveConversions.h"
+#include "mozilla/HoldDropJSObjects.h"
+#include "mozilla/dom/TypedArray.h"
+#include "nsContentUtils.h"
+#include "mozilla/dom/MediaKeys.h"
+
+namespace mozilla::dom {
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(MediaKeyMessageEvent)
+
+NS_IMPL_ADDREF_INHERITED(MediaKeyMessageEvent, Event)
+NS_IMPL_RELEASE_INHERITED(MediaKeyMessageEvent, Event)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(MediaKeyMessageEvent, Event)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(MediaKeyMessageEvent, Event)
+  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mMessage)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(MediaKeyMessageEvent, Event)
+  mozilla::DropJSObjects(tmp);
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MediaKeyMessageEvent)
+NS_INTERFACE_MAP_END_INHERITING(Event)
+
+MediaKeyMessageEvent::MediaKeyMessageEvent(EventTarget* aOwner)
+    : Event(aOwner, nullptr, nullptr),
+      mMessageType(static_cast<MediaKeyMessageType>(0)) {
+  mozilla::HoldJSObjects(this);
+}
+
+MediaKeyMessageEvent::~MediaKeyMessageEvent() { mozilla::DropJSObjects(this); }
+
+MediaKeyMessageEvent* MediaKeyMessageEvent::AsMediaKeyMessageEvent() {
+  return this;
+}
+
+JSObject* MediaKeyMessageEvent::WrapObjectInternal(
+    JSContext* aCx, JS::Handle<JSObject*> aGivenProto) {
+  return MediaKeyMessageEvent_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+already_AddRefed<MediaKeyMessageEvent> MediaKeyMessageEvent::Constructor(
+    EventTarget* aOwner, MediaKeyMessageType aMessageType,
+    const nsTArray<uint8_t>& aMessage) {
+  RefPtr<MediaKeyMessageEvent> e = new MediaKeyMessageEvent(aOwner);
+  e->InitEvent(u"message"_ns, false, false);
+  e->mMessageType = aMessageType;
+  e->mRawMessage = aMessage.Clone();
+  e->SetTrusted(true);
+  return e.forget();
+}
+
+already_AddRefed<MediaKeyMessageEvent> MediaKeyMessageEvent::Constructor(
+    const GlobalObject& aGlobal, const nsAString& aType,
+    const MediaKeyMessageEventInit& aEventInitDict, ErrorResult& aRv) {
+  nsCOMPtr<EventTarget> owner = do_QueryInterface(aGlobal.GetAsSupports());
+  RefPtr<MediaKeyMessageEvent> e = new MediaKeyMessageEvent(owner);
+  bool trusted = e->Init(owner);
+  e->InitEvent(aType, aEventInitDict.mBubbles, aEventInitDict.mCancelable);
+  JS::Rooted<JSObject*> buffer(aGlobal.Context(),
+                               aEventInitDict.mMessage.Obj());
+  e->mMessage = JS::CopyArrayBuffer(aGlobal.Context(), buffer);
+  if (!e->mMessage) {
+    aRv.NoteJSContextException(aGlobal.Context());
+    return nullptr;
+  }
+  e->mMessageType = aEventInitDict.mMessageType;
+  e->SetTrusted(trusted);
+  e->SetComposed(aEventInitDict.mComposed);
+  return e.forget();
+}
+
+void MediaKeyMessageEvent::GetMessage(JSContext* cx,
+                                      JS::MutableHandle<JSObject*> aMessage,
+                                      ErrorResult& aRv) {
+  if (!mMessage) {
+    mMessage = ArrayBuffer::Create(cx, this, mRawMessage.Length(),
+                                   mRawMessage.Elements());
+    if (!mMessage) {
+      aRv.NoteJSContextException(cx);
+      return;
+    }
+    mRawMessage.Clear();
+  }
+  aMessage.set(mMessage);
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/media/eme/MediaKeyMessageEvent.h b/dom/media/eme/MediaKeyMessageEvent.h
new file mode 100644
index 0000000000..400439b065
--- /dev/null
+++ b/dom/media/eme/MediaKeyMessageEvent.h
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef mozilla_dom_MediaKeyMessageEvent_h__
+#define mozilla_dom_MediaKeyMessageEvent_h__
+
+#include "mozilla/Attributes.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsWrapperCache.h"
+#include "nsCOMPtr.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/dom/TypedArray.h"
+#include "js/TypeDecls.h"
+#include "mozilla/dom/MediaKeyMessageEventBinding.h"
+
+namespace mozilla {
+class ErrorResult;
+
+namespace dom {
+
+struct MediaKeyMessageEventInit;
+
+class MediaKeyMessageEvent final : public Event {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(MediaKeyMessageEvent,
+                                                         Event)
+ protected:
+  virtual ~MediaKeyMessageEvent();
+  explicit MediaKeyMessageEvent(EventTarget* aOwner);
+
+  MediaKeyMessageType mMessageType;
+  JS::Heap<JSObject*> mMessage;
+
+ public:
+  virtual MediaKeyMessageEvent* AsMediaKeyMessageEvent();
+
+  JSObject* WrapObjectInternal(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+
+  static already_AddRefed<MediaKeyMessageEvent> Constructor(
+      EventTarget* aOwner, MediaKeyMessageType aMessageType,
+      const nsTArray<uint8_t>& aMessage);
+
+  static already_AddRefed<MediaKeyMessageEvent> Constructor(
+      const GlobalObject& aGlobal, const nsAString& aType,
+      const MediaKeyMessageEventInit& aEventInitDict, ErrorResult& aRv);
+
+  MediaKeyMessageType MessageType() const { return mMessageType; }
+
+  void GetMessage(JSContext* cx, JS::MutableHandle<JSObject*> aMessage,
+                  ErrorResult& aRv);
+
+ private:
+  nsTArray<uint8_t> mRawMessage;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_MediaKeyMessageEvent_h__
diff --git a/dom/media/eme/MediaKeySession.cpp b/dom/media/eme/MediaKeySession.cpp
new file mode 100644
index 0000000000..79190be710
--- /dev/null
+++ b/dom/media/eme/MediaKeySession.cpp
@@ -0,0 +1,622 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/MediaKeySession.h"
+
+#include <ctime>
+#include <utility>
+
+#include "GMPUtils.h"
+#include "mozilla/AsyncEventDispatcher.h"
+#include "mozilla/CDMProxy.h"
+#include "mozilla/EMEUtils.h"
+#include "mozilla/Encoding.h"
+#include "mozilla/dom/HTMLMediaElement.h"
+#include "mozilla/dom/KeyIdsInitDataBinding.h"
+#include "mozilla/dom/MediaEncryptedEvent.h"
+#include "mozilla/dom/MediaKeyError.h"
+#include "mozilla/dom/MediaKeyMessageEvent.h"
+#include "mozilla/dom/MediaKeyStatusMap.h"
+#include "mozilla/dom/MediaKeySystemAccess.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsPrintfCString.h"
+#include "psshparser/PsshParser.h"
+
+namespace mozilla::dom {
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(MediaKeySession, DOMEventTargetHelper,
+                                   mMediaKeyError, mKeys, mKeyStatusMap,
+                                   mClosed)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MediaKeySession)
+NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
+
+NS_IMPL_ADDREF_INHERITED(MediaKeySession, DOMEventTargetHelper)
+NS_IMPL_RELEASE_INHERITED(MediaKeySession, DOMEventTargetHelper)
+
+// Count of number of instances. Used to give each instance a
+// unique token.
+static uint32_t sMediaKeySessionNum = 0;
+
+// Max length of keyId in EME "keyIds" or WebM init data format, as enforced
+// by web platform tests.
+static const uint32_t MAX_KEY_ID_LENGTH = 512;
+
+// Max length of CENC PSSH init data tolerated, as enforced by web
+// platform tests.
+static const uint32_t MAX_CENC_INIT_DATA_LENGTH = 64 * 1024;
+
+MediaKeySession::MediaKeySession(nsPIDOMWindowInner* aParent, MediaKeys* aKeys,
+                                 const nsAString& aKeySystem,
+                                 MediaKeySessionType aSessionType,
+                                 ErrorResult& aRv)
+    : DOMEventTargetHelper(aParent),
+      mKeys(aKeys),
+      mKeySystem(aKeySystem),
+      mSessionType(aSessionType),
+      mToken(sMediaKeySessionNum++),
+      mIsClosed(false),
+      mUninitialized(true),
+      mKeyStatusMap(new MediaKeyStatusMap(aParent)),
+      mExpiration(JS::GenericNaN()) {
+  EME_LOG("MediaKeySession[%p,''] ctor", this);
+
+  MOZ_ASSERT(aParent);
+  if (aRv.Failed()) {
+    return;
+  }
+  mClosed = MakePromise(aRv, "MediaKeys.createSession"_ns);
+}
+
+void MediaKeySession::SetSessionId(const nsAString& aSessionId) {
+  EME_LOG("MediaKeySession[%p,'%s'] session Id set", this,
+          NS_ConvertUTF16toUTF8(aSessionId).get());
+
+  if (NS_WARN_IF(!mSessionId.IsEmpty())) {
+    return;
+  }
+  mSessionId = aSessionId;
+  mKeys->OnSessionIdReady(this);
+}
+
+MediaKeySession::~MediaKeySession() {
+  EME_LOG("MediaKeySession[%p,'%s'] dtor", this,
+          NS_ConvertUTF16toUTF8(mSessionId).get());
+}
+
+MediaKeyError* MediaKeySession::GetError() const { return mMediaKeyError; }
+
+void MediaKeySession::GetSessionId(nsString& aSessionId) const {
+  aSessionId = GetSessionId();
+}
+
+const nsString& MediaKeySession::GetSessionId() const { return mSessionId; }
+
+JSObject* MediaKeySession::WrapObject(JSContext* aCx,
+                                      JS::Handle<JSObject*> aGivenProto) {
+  return MediaKeySession_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+double MediaKeySession::Expiration() const { return mExpiration; }
+
+Promise* MediaKeySession::Closed() const { return mClosed; }
+
+void MediaKeySession::UpdateKeyStatusMap() {
+  MOZ_ASSERT(!IsClosed());
+  if (!mKeys->GetCDMProxy()) {
+    return;
+  }
+
+  nsTArray<CDMCaps::KeyStatus> keyStatuses;
+  {
+    auto caps = mKeys->GetCDMProxy()->Capabilites().Lock();
+    caps->GetKeyStatusesForSession(mSessionId, keyStatuses);
+  }
+
+  mKeyStatusMap->Update(keyStatuses);
+
+  if (EME_LOG_ENABLED()) {
+    nsAutoCString message(
+        nsPrintfCString("MediaKeySession[%p,'%s'] key statuses change {", this,
+                        NS_ConvertUTF16toUTF8(mSessionId).get()));
+    for (const CDMCaps::KeyStatus& status : keyStatuses) {
+      message.Append(nsPrintfCString(
+          " (%s,%s)", ToHexString(status.mId).get(),
+          nsCString(MediaKeyStatusValues::GetString(status.mStatus)).get()));
+    }
+    message.AppendLiteral(" }");
+    // Use %s so we aren't exposing random strings to printf interpolation.
+    EME_LOG("%s", message.get());
+  }
+}
+
+MediaKeyStatusMap* MediaKeySession::KeyStatuses() const {
+  return mKeyStatusMap;
+}
+
+// The user agent MUST thoroughly validate the Initialization Data before
+// passing it to the CDM. This includes verifying that the length and
+// values of fields are reasonable, verifying that values are within
+// reasonable limits, and stripping irrelevant, unsupported, or unknown
+// data or fields. It is RECOMMENDED that user agents pre-parse, sanitize,
+// and/or generate a fully sanitized version of the Initialization Data.
+// If the Initialization Data format specified by initDataType supports
+// multiple entries, the user agent SHOULD remove entries that are not
+// needed by the CDM. The user agent MUST NOT re-order entries within
+// the Initialization Data.
+static bool ValidateInitData(const nsTArray<uint8_t>& aInitData,
+                             const nsAString& aInitDataType) {
+  if (aInitDataType.LowerCaseEqualsLiteral("webm")) {
+    // WebM initData consists of a single keyId. Ensure it's of reasonable
+    // length.
+    return aInitData.Length() <= MAX_KEY_ID_LENGTH;
+  } else if (aInitDataType.LowerCaseEqualsLiteral("cenc")) {
+    // Limit initData to less than 64KB.
+    if (aInitData.Length() > MAX_CENC_INIT_DATA_LENGTH) {
+      return false;
+    }
+    std::vector<std::vector<uint8_t>> keyIds;
+    return ParseCENCInitData(aInitData.Elements(), aInitData.Length(), keyIds);
+  } else if (aInitDataType.LowerCaseEqualsLiteral("keyids")) {
+    if (aInitData.Length() > MAX_KEY_ID_LENGTH) {
+      return false;
+    }
+    // Ensure that init data matches the expected JSON format.
+    mozilla::dom::KeyIdsInitData keyIds;
+    nsString json;
+    nsDependentCSubstring raw(
+        reinterpret_cast<const char*>(aInitData.Elements()),
+        aInitData.Length());
+    if (NS_FAILED(UTF_8_ENCODING->DecodeWithBOMRemoval(raw, json))) {
+      return false;
+    }
+    if (!keyIds.Init(json)) {
+      return false;
+    }
+    if (keyIds.mKids.Length() == 0) {
+      return false;
+    }
+    for (const auto& kid : keyIds.mKids) {
+      if (kid.IsEmpty()) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+// Generates a license request based on the initData. A message of type
+// "license-request" or "individualization-request" will always be queued
+// if the algorithm succeeds and the promise is resolved.
+already_AddRefed<Promise> MediaKeySession::GenerateRequest(
+    const nsAString& aInitDataType,
+    const ArrayBufferViewOrArrayBuffer& aInitData, ErrorResult& aRv) {
+  RefPtr<DetailedPromise> promise(
+      MakePromise(aRv, "MediaKeySession.generateRequest"_ns));
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // If this object is closed, return a promise rejected with an
+  // InvalidStateError.
+  if (IsClosed()) {
+    EME_LOG("MediaKeySession[%p,'%s'] GenerateRequest() failed, closed", this,
+            NS_ConvertUTF16toUTF8(mSessionId).get());
+    promise->MaybeRejectWithInvalidStateError(
+        "Session is closed in MediaKeySession.generateRequest()");
+    return promise.forget();
+  }
+
+  // If this object's uninitialized value is false, return a promise rejected
+  // with an InvalidStateError.
+  if (!mUninitialized) {
+    EME_LOG("MediaKeySession[%p,'%s'] GenerateRequest() failed, uninitialized",
+            this, NS_ConvertUTF16toUTF8(mSessionId).get());
+    promise->MaybeRejectWithInvalidStateError(
+        "Session is already initialized in MediaKeySession.generateRequest()");
+    return promise.forget();
+  }
+
+  // Let this object's uninitialized value be false.
+  mUninitialized = false;
+
+  // If initDataType is the empty string, return a promise rejected
+  // with a newly created TypeError.
+  if (aInitDataType.IsEmpty()) {
+    promise->MaybeRejectWithTypeError(
+        "Empty initDataType passed to MediaKeySession.generateRequest()");
+    EME_LOG(
+        "MediaKeySession[%p,'%s'] GenerateRequest() failed, empty initDataType",
+        this, NS_ConvertUTF16toUTF8(mSessionId).get());
+    return promise.forget();
+  }
+
+  // If initData is an empty array, return a promise rejected with
+  // a newly created TypeError.
+  nsTArray<uint8_t> data;
+  CopyArrayBufferViewOrArrayBufferData(aInitData, data);
+  if (data.IsEmpty()) {
+    promise->MaybeRejectWithTypeError(
+        "Empty initData passed to MediaKeySession.generateRequest()");
+    EME_LOG("MediaKeySession[%p,'%s'] GenerateRequest() failed, empty initData",
+            this, NS_ConvertUTF16toUTF8(mSessionId).get());
+    return promise.forget();
+  }
+
+  // If the Key System implementation represented by this object's
+  // cdm implementation value does not support initDataType as an
+  // Initialization Data Type, return a promise rejected with a
+  // NotSupportedError. String comparison is case-sensitive.
+  if (!MediaKeySystemAccess::KeySystemSupportsInitDataType(mKeySystem,
+                                                           aInitDataType)) {
+    promise->MaybeRejectWithNotSupportedError(
+        "Unsupported initDataType passed to MediaKeySession.generateRequest()");
+    EME_LOG(
+        "MediaKeySession[%p,'%s'] GenerateRequest() failed, unsupported "
+        "initDataType",
+        this, NS_ConvertUTF16toUTF8(mSessionId).get());
+    return promise.forget();
+  }
+
+  // Let init data be a copy of the contents of the initData parameter.
+  // Note: Handled by the CopyArrayBufferViewOrArrayBufferData call above.
+
+  // Let session type be this object's session type.
+
+  // Let promise be a new promise.
+
+  // Run the following steps in parallel:
+
+  // If the init data is not valid for initDataType, reject promise with
+  // a newly created TypeError.
+  if (!ValidateInitData(data, aInitDataType)) {
+    // If the preceding step failed, reject promise with a newly created
+    // TypeError.
+    promise->MaybeRejectWithTypeError(
+        "initData sanitization failed in MediaKeySession.generateRequest()");
+    EME_LOG(
+        "MediaKeySession[%p,'%s'] GenerateRequest() initData sanitization "
+        "failed",
+        this, NS_ConvertUTF16toUTF8(mSessionId).get());
+    return promise.forget();
+  }
+
+  // Let sanitized init data be a validated and sanitized version of init data.
+
+  // If sanitized init data is empty, reject promise with a NotSupportedError.
+
+  // Note: Remaining steps of generateRequest method continue in CDM.
+
+  // Convert initData to hex for easier logging.
+  // Note: CreateSession() std::move()s the data out of the array, so we have
+  // to copy it here.
+  nsAutoCString hexInitData(ToHexString(data));
+  PromiseId pid = mKeys->StorePromise(promise);
+  mKeys->ConnectPendingPromiseIdWithToken(pid, Token());
+  mKeys->GetCDMProxy()->CreateSession(Token(), mSessionType, pid, aInitDataType,
+                                      data);
+
+  EME_LOG(
+      "MediaKeySession[%p,'%s'] GenerateRequest() sent, "
+      "promiseId=%d initData='%s' initDataType='%s'",
+      this, NS_ConvertUTF16toUTF8(mSessionId).get(), pid, hexInitData.get(),
+      NS_ConvertUTF16toUTF8(aInitDataType).get());
+
+  return promise.forget();
+}
+
+already_AddRefed<Promise> MediaKeySession::Load(const nsAString& aSessionId,
+                                                ErrorResult& aRv) {
+  RefPtr<DetailedPromise> promise(MakePromise(aRv, "MediaKeySession.load"_ns));
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // 1. If this object is closed, return a promise rejected with an
+  // InvalidStateError.
+  if (IsClosed()) {
+    promise->MaybeRejectWithInvalidStateError(
+        "Session is closed in MediaKeySession.load()");
+    EME_LOG("MediaKeySession[%p,'%s'] Load() failed, closed", this,
+            NS_ConvertUTF16toUTF8(aSessionId).get());
+    return promise.forget();
+  }
+
+  // 2.If this object's uninitialized value is false, return a promise rejected
+  // with an InvalidStateError.
+  if (!mUninitialized) {
+    promise->MaybeRejectWithInvalidStateError(
+        "Session is already initialized in MediaKeySession.load()");
+    EME_LOG("MediaKeySession[%p,'%s'] Load() failed, uninitialized", this,
+            NS_ConvertUTF16toUTF8(aSessionId).get());
+    return promise.forget();
+  }
+
+  // 3.Let this object's uninitialized value be false.
+  mUninitialized = false;
+
+  // 4. If sessionId is the empty string, return a promise rejected with a newly
+  // created TypeError.
+  if (aSessionId.IsEmpty()) {
+    promise->MaybeRejectWithTypeError(
+        "Trying to load a session with empty session ID");
+    // "The sessionId parameter is empty."
+    EME_LOG("MediaKeySession[%p,''] Load() failed, no sessionId", this);
+    return promise.forget();
+  }
+
+  // 5. If the result of running the Is persistent session type? algorithm
+  // on this object's session type is false, return a promise rejected with
+  // a newly created TypeError.
+  if (mSessionType == MediaKeySessionType::Temporary) {
+    promise->MaybeRejectWithTypeError(
+        "Trying to load() into a non-persistent session");
+    EME_LOG(
+        "MediaKeySession[%p,''] Load() failed, can't load in a non-persistent "
+        "session",
+        this);
+    return promise.forget();
+  }
+
+  // Note: We don't support persistent sessions in any keysystem, so all calls
+  // to Load() should reject with a TypeError in the preceding check. Omitting
+  // implementing the rest of the specified MediaKeySession::Load() algorithm.
+
+  // We now know the sessionId being loaded into this session. Remove the
+  // session from its owning MediaKey's set of sessions awaiting a sessionId.
+  RefPtr<MediaKeySession> session(mKeys->GetPendingSession(Token()));
+  MOZ_ASSERT(session == this, "Session should be awaiting id on its own token");
+
+  // Associate with the known sessionId.
+  SetSessionId(aSessionId);
+
+  PromiseId pid = mKeys->StorePromise(promise);
+  mKeys->GetCDMProxy()->LoadSession(pid, mSessionType, aSessionId);
+
+  EME_LOG("MediaKeySession[%p,'%s'] Load() sent to CDM, promiseId=%d", this,
+          NS_ConvertUTF16toUTF8(mSessionId).get(), pid);
+
+  return promise.forget();
+}
+
+already_AddRefed<Promise> MediaKeySession::Update(
+    const ArrayBufferViewOrArrayBuffer& aResponse, ErrorResult& aRv) {
+  RefPtr<DetailedPromise> promise(
+      MakePromise(aRv, "MediaKeySession.update"_ns));
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  if (!IsCallable()) {
+    // If this object's callable value is false, return a promise rejected
+    // with a new DOMException whose name is InvalidStateError.
+    EME_LOG(
+        "MediaKeySession[%p,''] Update() called before sessionId set by CDM",
+        this);
+    promise->MaybeRejectWithInvalidStateError(
+        "MediaKeySession.Update() called before sessionId set by CDM");
+    return promise.forget();
+  }
+
+  nsTArray<uint8_t> data;
+  if (IsClosed() || !mKeys->GetCDMProxy()) {
+    promise->MaybeRejectWithInvalidStateError(
+        "Session is closed or was not properly initialized");
+    EME_LOG(
+        "MediaKeySession[%p,'%s'] Update() failed, session is closed or was "
+        "not properly initialised.",
+        this, NS_ConvertUTF16toUTF8(mSessionId).get());
+    return promise.forget();
+  }
+  CopyArrayBufferViewOrArrayBufferData(aResponse, data);
+  if (data.IsEmpty()) {
+    promise->MaybeRejectWithTypeError(
+        "Empty response buffer passed to MediaKeySession.update()");
+    EME_LOG("MediaKeySession[%p,'%s'] Update() failed, empty response buffer",
+            this, NS_ConvertUTF16toUTF8(mSessionId).get());
+    return promise.forget();
+  }
+
+  // Convert response to hex for easier logging.
+  // Note: UpdateSession() std::move()s the data out of the array, so we have
+  // to copy it here.
+  nsAutoCString hexResponse(ToHexString(data));
+
+  PromiseId pid = mKeys->StorePromise(promise);
+  mKeys->GetCDMProxy()->UpdateSession(mSessionId, pid, data);
+
+  EME_LOG(
+      "MediaKeySession[%p,'%s'] Update() sent to CDM, "
+      "promiseId=%d Response='%s'",
+      this, NS_ConvertUTF16toUTF8(mSessionId).get(), pid, hexResponse.get());
+
+  return promise.forget();
+}
+
+already_AddRefed<Promise> MediaKeySession::Close(ErrorResult& aRv) {
+  RefPtr<DetailedPromise> promise(MakePromise(aRv, "MediaKeySession.close"_ns));
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+  // 1. Let session be the associated MediaKeySession object.
+  // 2. If session is closed, return a resolved promise.
+  if (IsClosed()) {
+    EME_LOG("MediaKeySession[%p,'%s'] Close() already closed", this,
+            NS_ConvertUTF16toUTF8(mSessionId).get());
+    promise->MaybeResolveWithUndefined();
+    return promise.forget();
+  }
+  // 3. If session's callable value is false, return a promise rejected
+  // with an InvalidStateError.
+  if (!IsCallable()) {
+    EME_LOG("MediaKeySession[%p,''] Close() called before sessionId set by CDM",
+            this);
+    promise->MaybeRejectWithInvalidStateError(
+        "MediaKeySession.Close() called before sessionId set by CDM");
+    return promise.forget();
+  }
+  if (!mKeys->GetCDMProxy()) {
+    EME_LOG("MediaKeySession[%p,'%s'] Close() null CDMProxy", this,
+            NS_ConvertUTF16toUTF8(mSessionId).get());
+    promise->MaybeRejectWithInvalidStateError(
+        "MediaKeySession.Close() lost reference to CDM");
+    return promise.forget();
+  }
+  // 4. Let promise be a new promise.
+  PromiseId pid = mKeys->StorePromise(promise);
+  // 5. Run the following steps in parallel:
+  // 5.1 Let cdm be the CDM instance represented by session's cdm instance
+  // value. 5.2 Use cdm to close the session associated with session.
+  mKeys->GetCDMProxy()->CloseSession(mSessionId, pid);
+
+  EME_LOG("MediaKeySession[%p,'%s'] Close() sent to CDM, promiseId=%d", this,
+          NS_ConvertUTF16toUTF8(mSessionId).get(), pid);
+
+  // Session Closed algorithm is run when CDM causes us to run
+  // OnSessionClosed().
+
+  // 6. Return promise.
+  return promise.forget();
+}
+
+void MediaKeySession::OnClosed() {
+  if (IsClosed()) {
+    return;
+  }
+  EME_LOG("MediaKeySession[%p,'%s'] session close operation complete.", this,
+          NS_ConvertUTF16toUTF8(mSessionId).get());
+  mIsClosed = true;
+  mKeys->OnSessionClosed(this);
+  mKeys = nullptr;
+  mClosed->MaybeResolveWithUndefined();
+}
+
+bool MediaKeySession::IsClosed() const { return mIsClosed; }
+
+already_AddRefed<Promise> MediaKeySession::Remove(ErrorResult& aRv) {
+  RefPtr<DetailedPromise> promise(
+      MakePromise(aRv, "MediaKeySession.remove"_ns));
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+  if (!IsCallable()) {
+    // If this object's callable value is false, return a promise rejected
+    // with a new DOMException whose name is InvalidStateError.
+    EME_LOG(
+        "MediaKeySession[%p,''] Remove() called before sessionId set by CDM",
+        this);
+    promise->MaybeRejectWithInvalidStateError(
+        "MediaKeySession.Remove() called before sessionId set by CDM");
+    return promise.forget();
+  }
+  if (mSessionType != MediaKeySessionType::Persistent_license) {
+    promise->MaybeRejectWithInvalidAccessError(
+        "Calling MediaKeySession.remove() on non-persistent session");
+    // "The operation is not supported on session type sessions."
+    EME_LOG("MediaKeySession[%p,'%s'] Remove() failed, sesion not persisrtent.",
+            this, NS_ConvertUTF16toUTF8(mSessionId).get());
+    return promise.forget();
+  }
+  if (IsClosed() || !mKeys->GetCDMProxy()) {
+    promise->MaybeRejectWithInvalidStateError(
+        "MediaKeySession.remove() called but session is not active");
+    // "The session is closed."
+    EME_LOG("MediaKeySession[%p,'%s'] Remove() failed, already session closed.",
+            this, NS_ConvertUTF16toUTF8(mSessionId).get());
+    return promise.forget();
+  }
+  PromiseId pid = mKeys->StorePromise(promise);
+  mKeys->GetCDMProxy()->RemoveSession(mSessionId, pid);
+  EME_LOG("MediaKeySession[%p,'%s'] Remove() sent to CDM, promiseId=%d.", this,
+          NS_ConvertUTF16toUTF8(mSessionId).get(), pid);
+
+  return promise.forget();
+}
+
+void MediaKeySession::DispatchKeyMessage(MediaKeyMessageType aMessageType,
+                                         const nsTArray<uint8_t>& aMessage) {
+  if (EME_LOG_ENABLED()) {
+    EME_LOG(
+        "MediaKeySession[%p,'%s'] DispatchKeyMessage() type=%s message='%s'",
+        this, NS_ConvertUTF16toUTF8(mSessionId).get(),
+        nsCString(MediaKeyMessageTypeValues::GetString(aMessageType)).get(),
+        ToHexString(aMessage).get());
+  }
+
+  RefPtr<MediaKeyMessageEvent> event(
+      MediaKeyMessageEvent::Constructor(this, aMessageType, aMessage));
+  RefPtr<AsyncEventDispatcher> asyncDispatcher =
+      new AsyncEventDispatcher(this, event);
+  asyncDispatcher->PostDOMEvent();
+}
+
+void MediaKeySession::DispatchKeyError(uint32_t aSystemCode) {
+  EME_LOG("MediaKeySession[%p,'%s'] DispatchKeyError() systemCode=%u.", this,
+          NS_ConvertUTF16toUTF8(mSessionId).get(), aSystemCode);
+
+  RefPtr<MediaKeyError> event(new MediaKeyError(this, aSystemCode));
+  RefPtr<AsyncEventDispatcher> asyncDispatcher =
+      new AsyncEventDispatcher(this, event);
+  asyncDispatcher->PostDOMEvent();
+}
+
+void MediaKeySession::DispatchKeyStatusesChange() {
+  if (IsClosed()) {
+    return;
+  }
+
+  UpdateKeyStatusMap();
+
+  RefPtr<AsyncEventDispatcher> asyncDispatcher =
+      new AsyncEventDispatcher(this, u"keystatuseschange"_ns, CanBubble::eNo);
+  asyncDispatcher->PostDOMEvent();
+}
+
+uint32_t MediaKeySession::Token() const { return mToken; }
+
+already_AddRefed<DetailedPromise> MediaKeySession::MakePromise(
+    ErrorResult& aRv, const nsACString& aName) {
+  nsCOMPtr<nsIGlobalObject> global = GetParentObject();
+  if (!global) {
+    NS_WARNING("Passed non-global to MediaKeys ctor!");
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+  return DetailedPromise::Create(global, aRv, aName);
+}
+
+void MediaKeySession::SetExpiration(double aExpiration) {
+  EME_LOG("MediaKeySession[%p,'%s'] SetExpiry(%.12lf) (%.2lf hours from now)",
+          this, NS_ConvertUTF16toUTF8(mSessionId).get(), aExpiration,
+          (aExpiration - 1000.0 * double(time(0))) / (1000.0 * 60 * 60));
+  mExpiration = aExpiration;
+}
+
+EventHandlerNonNull* MediaKeySession::GetOnkeystatuseschange() {
+  return GetEventHandler(nsGkAtoms::onkeystatuseschange);
+}
+
+void MediaKeySession::SetOnkeystatuseschange(EventHandlerNonNull* aCallback) {
+  SetEventHandler(nsGkAtoms::onkeystatuseschange, aCallback);
+}
+
+EventHandlerNonNull* MediaKeySession::GetOnmessage() {
+  return GetEventHandler(nsGkAtoms::onmessage);
+}
+
+void MediaKeySession::SetOnmessage(EventHandlerNonNull* aCallback) {
+  SetEventHandler(nsGkAtoms::onmessage, aCallback);
+}
+
+nsCString ToCString(MediaKeySessionType aType) {
+  return nsCString(MediaKeySessionTypeValues::GetString(aType));
+}
+
+nsString ToString(MediaKeySessionType aType) {
+  return NS_ConvertUTF8toUTF16(ToCString(aType));
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/media/eme/MediaKeySession.h b/dom/media/eme/MediaKeySession.h
new file mode 100644
index 0000000000..e19488c311
--- /dev/null
+++ b/dom/media/eme/MediaKeySession.h
@@ -0,0 +1,142 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef mozilla_dom_MediaKeySession_h
+#define mozilla_dom_MediaKeySession_h
+
+#include "DecoderDoctorLogger.h"
+#include "mozilla/Attributes.h"
+#include "nsCycleCollectionParticipant.h"
+#include "mozilla/DOMEventTargetHelper.h"
+#include "nsCOMPtr.h"
+#include "mozilla/dom/TypedArray.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/DetailedPromise.h"
+#include "mozilla/dom/MediaKeySessionBinding.h"
+#include "mozilla/dom/MediaKeysBinding.h"
+#include "mozilla/dom/MediaKeyMessageEventBinding.h"
+
+struct JSContext;
+
+namespace mozilla {
+class ErrorResult;
+
+namespace dom {
+class MediaKeySession;
+}  // namespace dom
+DDLoggedTypeName(dom::MediaKeySession);
+
+namespace dom {
+
+class ArrayBufferViewOrArrayBuffer;
+class MediaKeyError;
+class MediaKeyStatusMap;
+
+nsCString ToCString(MediaKeySessionType aType);
+
+nsString ToString(MediaKeySessionType aType);
+
+class MediaKeySession final : public DOMEventTargetHelper,
+                              public DecoderDoctorLifeLogger<MediaKeySession> {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(MediaKeySession,
+                                           DOMEventTargetHelper)
+ public:
+  MediaKeySession(nsPIDOMWindowInner* aParent, MediaKeys* aKeys,
+                  const nsAString& aKeySystem, MediaKeySessionType aSessionType,
+                  ErrorResult& aRv);
+
+  void SetSessionId(const nsAString& aSessionId);
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+
+  // Mark this as resultNotAddRefed to return raw pointers
+  MediaKeyError* GetError() const;
+
+  MediaKeyStatusMap* KeyStatuses() const;
+
+  void GetSessionId(nsString& aRetval) const;
+
+  const nsString& GetSessionId() const;
+
+  // Number of ms since epoch at which expiration occurs, or NaN if unknown.
+  // TODO: The type of this attribute is still under contention.
+  // https://www.w3.org/Bugs/Public/show_bug.cgi?id=25902
+  double Expiration() const;
+
+  Promise* Closed() const;
+
+  already_AddRefed<Promise> GenerateRequest(
+      const nsAString& aInitDataType,
+      const ArrayBufferViewOrArrayBuffer& aInitData, ErrorResult& aRv);
+
+  already_AddRefed<Promise> Load(const nsAString& aSessionId, ErrorResult& aRv);
+
+  already_AddRefed<Promise> Update(const ArrayBufferViewOrArrayBuffer& response,
+                                   ErrorResult& aRv);
+
+  already_AddRefed<Promise> Close(ErrorResult& aRv);
+
+  already_AddRefed<Promise> Remove(ErrorResult& aRv);
+
+  void DispatchKeyMessage(MediaKeyMessageType aMessageType,
+                          const nsTArray<uint8_t>& aMessage);
+
+  void DispatchKeyError(uint32_t system_code);
+
+  void DispatchKeyStatusesChange();
+
+  void OnClosed();
+
+  bool IsClosed() const;
+
+  void SetExpiration(double aExpiry);
+
+  mozilla::dom::EventHandlerNonNull* GetOnkeystatuseschange();
+  void SetOnkeystatuseschange(mozilla::dom::EventHandlerNonNull* aCallback);
+
+  mozilla::dom::EventHandlerNonNull* GetOnmessage();
+  void SetOnmessage(mozilla::dom::EventHandlerNonNull* aCallback);
+
+  // Process-unique identifier.
+  uint32_t Token() const;
+
+ private:
+  ~MediaKeySession();
+
+  void UpdateKeyStatusMap();
+
+  bool IsCallable() const {
+    // The EME spec sets the "callable value" to true whenever the CDM sets
+    // the sessionId. When the session is initialized, sessionId is empty and
+    // callable is thus false.
+    return !mSessionId.IsEmpty();
+  }
+
+  already_AddRefed<DetailedPromise> MakePromise(ErrorResult& aRv,
+                                                const nsACString& aName);
+
+  RefPtr<DetailedPromise> mClosed;
+
+  RefPtr<MediaKeyError> mMediaKeyError;
+  RefPtr<MediaKeys> mKeys;
+  const nsString mKeySystem;
+  nsString mSessionId;
+  const MediaKeySessionType mSessionType;
+  const uint32_t mToken;
+  bool mIsClosed;
+  bool mUninitialized;
+  RefPtr<MediaKeyStatusMap> mKeyStatusMap;
+  double mExpiration;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif
diff --git a/dom/media/eme/MediaKeyStatusMap.cpp b/dom/media/eme/MediaKeyStatusMap.cpp
new file mode 100644
index 0000000000..c53f516423
--- /dev/null
+++ b/dom/media/eme/MediaKeyStatusMap.cpp
@@ -0,0 +1,99 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/MediaKeyStatusMap.h"
+#include "nsPIDOMWindow.h"
+#include "mozilla/dom/UnionTypes.h"
+#include "mozilla/dom/ToJSValue.h"
+#include "mozilla/EMEUtils.h"
+#include "GMPUtils.h"
+
+namespace mozilla::dom {
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(MediaKeyStatusMap)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(MediaKeyStatusMap)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MediaKeyStatusMap)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(MediaKeyStatusMap, mParent)
+
+MediaKeyStatusMap::MediaKeyStatusMap(nsPIDOMWindowInner* aParent)
+    : mParent(aParent) {}
+
+MediaKeyStatusMap::~MediaKeyStatusMap() = default;
+
+JSObject* MediaKeyStatusMap::WrapObject(JSContext* aCx,
+                                        JS::Handle<JSObject*> aGivenProto) {
+  return MediaKeyStatusMap_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+nsPIDOMWindowInner* MediaKeyStatusMap::GetParentObject() const {
+  return mParent;
+}
+
+void MediaKeyStatusMap::Get(const ArrayBufferViewOrArrayBuffer& aKey,
+                            OwningMediaKeyStatusOrUndefined& aOutValue,
+                            ErrorResult& aOutRv) const {
+  ArrayData keyId = GetArrayBufferViewOrArrayBufferData(aKey);
+  if (!keyId.IsValid()) {
+    aOutValue.SetUndefined();
+    return;
+  }
+  for (const KeyStatus& status : mStatuses) {
+    if (keyId == status.mKeyId) {
+      aOutValue.SetAsMediaKeyStatus() = status.mStatus;
+      return;
+    }
+  }
+  aOutValue.SetUndefined();
+}
+
+bool MediaKeyStatusMap::Has(const ArrayBufferViewOrArrayBuffer& aKey) const {
+  ArrayData keyId = GetArrayBufferViewOrArrayBufferData(aKey);
+  if (!keyId.IsValid()) {
+    return false;
+  }
+
+  for (const KeyStatus& status : mStatuses) {
+    if (keyId == status.mKeyId) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+uint32_t MediaKeyStatusMap::GetIterableLength() const {
+  return mStatuses.Length();
+}
+
+TypedArrayCreator<ArrayBuffer> MediaKeyStatusMap::GetKeyAtIndex(
+    uint32_t aIndex) const {
+  MOZ_ASSERT(aIndex < GetIterableLength());
+  return TypedArrayCreator<ArrayBuffer>(mStatuses[aIndex].mKeyId);
+}
+
+nsString MediaKeyStatusMap::GetKeyIDAsHexString(uint32_t aIndex) const {
+  MOZ_ASSERT(aIndex < GetIterableLength());
+  return NS_ConvertUTF8toUTF16(ToHexString(mStatuses[aIndex].mKeyId));
+}
+
+MediaKeyStatus MediaKeyStatusMap::GetValueAtIndex(uint32_t aIndex) const {
+  MOZ_ASSERT(aIndex < GetIterableLength());
+  return mStatuses[aIndex].mStatus;
+}
+
+uint32_t MediaKeyStatusMap::Size() const { return mStatuses.Length(); }
+
+void MediaKeyStatusMap::Update(const nsTArray<CDMCaps::KeyStatus>& aKeys) {
+  mStatuses.Clear();
+  for (const auto& key : aKeys) {
+    mStatuses.InsertElementSorted(KeyStatus(key.mId, key.mStatus));
+  }
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/media/eme/MediaKeyStatusMap.h b/dom/media/eme/MediaKeyStatusMap.h
new file mode 100644
index 0000000000..35027b25e2
--- /dev/null
+++ b/dom/media/eme/MediaKeyStatusMap.h
@@ -0,0 +1,92 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef mozilla_dom_MediaKeyStatuses_h
+#define mozilla_dom_MediaKeyStatuses_h
+
+#include "mozilla/Attributes.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsWrapperCache.h"
+
+#include "mozilla/dom/TypedArray.h"
+#include "mozilla/dom/MediaKeyStatusMapBinding.h"
+#include "mozilla/CDMCaps.h"
+
+class nsPIDOMWindowInner;
+
+namespace mozilla {
+class ErrorResult;
+
+namespace dom {
+
+class ArrayBufferViewOrArrayBuffer;
+
+// The MediaKeyStatusMap WebIDL interface; maps a keyId to its status.
+// Note that the underlying "map" is stored in an array, since we assume
+// that a MediaKeySession won't have many key statuses to report.
+class MediaKeyStatusMap final : public nsISupports, public nsWrapperCache {
+ public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(MediaKeyStatusMap)
+
+ public:
+  explicit MediaKeyStatusMap(nsPIDOMWindowInner* aParent);
+
+ protected:
+  ~MediaKeyStatusMap();
+
+ public:
+  nsPIDOMWindowInner* GetParentObject() const;
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+
+  void Get(const ArrayBufferViewOrArrayBuffer& aKey,
+           OwningMediaKeyStatusOrUndefined& aOutValue,
+           ErrorResult& aOutRv) const;
+  bool Has(const ArrayBufferViewOrArrayBuffer& aKey) const;
+  uint32_t Size() const;
+
+  uint32_t GetIterableLength() const;
+  TypedArrayCreator<ArrayBuffer> GetKeyAtIndex(uint32_t aIndex) const;
+  nsString GetKeyIDAsHexString(uint32_t aIndex) const;
+  MediaKeyStatus GetValueAtIndex(uint32_t aIndex) const;
+
+  void Update(const nsTArray<CDMCaps::KeyStatus>& keys);
+
+ private:
+  nsCOMPtr<nsPIDOMWindowInner> mParent;
+
+  struct KeyStatus {
+    KeyStatus(const nsTArray<uint8_t>& aKeyId, MediaKeyStatus aStatus)
+        : mKeyId(aKeyId.Clone()), mStatus(aStatus) {}
+    bool operator==(const KeyStatus& aOther) const {
+      return aOther.mKeyId == mKeyId;
+    }
+    bool operator<(const KeyStatus& aOther) const {
+      // Copy chromium and compare keys' bytes.
+      // Update once https://github.com/w3c/encrypted-media/issues/69
+      // is resolved.
+      const nsTArray<uint8_t>& other = aOther.mKeyId;
+      const nsTArray<uint8_t>& self = mKeyId;
+      size_t length = std::min<size_t>(other.Length(), self.Length());
+      int cmp = memcmp(self.Elements(), other.Elements(), length);
+      if (cmp != 0) {
+        return cmp < 0;
+      }
+      return self.Length() <= other.Length();
+    }
+    nsTArray<uint8_t> mKeyId;
+    MediaKeyStatus mStatus;
+  };
+
+  nsTArray<KeyStatus> mStatuses;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif
diff --git a/dom/media/eme/MediaKeySystemAccess.cpp b/dom/media/eme/MediaKeySystemAccess.cpp
new file mode 100644
index 0000000000..0d61226eb5
--- /dev/null
+++ b/dom/media/eme/MediaKeySystemAccess.cpp
@@ -0,0 +1,1086 @@
+/* -*- 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 "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
+
+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 MediaKeySystemStatus EnsureCDMInstalled(const nsAString& aKeySystem,
+                                               nsACString& aOutMessage) {
+  if (!KeySystemConfig::Supports(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
+    }
+  }
+
+#ifdef MOZ_WMF_CDM
+  if (IsPlayReadyKeySystemAndSupported(aKeySystem) &&
+      KeySystemConfig::Supports(aKeySystem)) {
+    return MediaKeySystemStatus::Available;
+  }
+#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;
+  }
+  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),
+#endif
+  };
+  for (const auto& name : keySystemNames) {
+    KeySystemConfig config;
+    if (KeySystemConfig::GetConfig(name, config)) {
+      if (IsClearkeyKeySystem(name) &&
+          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{config};
+        clearkeyWithProtectionQuery.mKeySystem.AssignLiteral(
+            kClearKeyWithProtectionQueryKeySystemName);
+        keySystemConfigs.AppendElement(std::move(clearkeyWithProtectionQuery));
+      }
+      keySystemConfigs.AppendElement(std::move(config));
+    }
+  }
+
+  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 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)) {
+    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 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(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 = 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 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) {
+  // 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) {
+  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
diff --git a/dom/media/eme/MediaKeySystemAccess.h b/dom/media/eme/MediaKeySystemAccess.h
new file mode 100644
index 0000000000..b7ad9086b1
--- /dev/null
+++ b/dom/media/eme/MediaKeySystemAccess.h
@@ -0,0 +1,81 @@
+/* -*- 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/. */
+
+#ifndef mozilla_dom_MediaKeySystemAccess_h
+#define mozilla_dom_MediaKeySystemAccess_h
+
+#include "mozilla/Attributes.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsWrapperCache.h"
+
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/MediaKeySystemAccessBinding.h"
+#include "mozilla/dom/MediaKeysRequestStatusBinding.h"
+
+#include "js/TypeDecls.h"
+
+namespace mozilla {
+
+class DecoderDoctorDiagnostics;
+class ErrorResult;
+
+namespace dom {
+
+class MediaKeySystemAccess final : public nsISupports, public nsWrapperCache {
+ public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(MediaKeySystemAccess)
+
+ public:
+  explicit MediaKeySystemAccess(nsPIDOMWindowInner* aParent,
+                                const nsAString& aKeySystem,
+                                const MediaKeySystemConfiguration& aConfig);
+
+ protected:
+  ~MediaKeySystemAccess();
+
+ public:
+  nsPIDOMWindowInner* GetParentObject() const;
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+
+  void GetKeySystem(nsString& aRetVal) const;
+
+  void GetConfiguration(MediaKeySystemConfiguration& aConfig);
+
+  already_AddRefed<Promise> CreateMediaKeys(ErrorResult& aRv);
+
+  static MediaKeySystemStatus GetKeySystemStatus(
+      const nsAString& aKeySystem, nsACString& aOutExceptionMessage);
+
+  static void NotifyObservers(nsPIDOMWindowInner* aWindow,
+                              const nsAString& aKeySystem,
+                              MediaKeySystemStatus aStatus);
+
+  static bool GetSupportedConfig(
+      const nsAString& aKeySystem,
+      const Sequence<MediaKeySystemConfiguration>& aConfigs,
+      MediaKeySystemConfiguration& aOutConfig,
+      DecoderDoctorDiagnostics* aDiagnostics, bool aIsPrivateBrowsing,
+      const std::function<void(const char*)>& aDeprecationLogFn);
+
+  static bool KeySystemSupportsInitDataType(const nsAString& aKeySystem,
+                                            const nsAString& aInitDataType);
+
+  static nsCString ToCString(
+      const Sequence<MediaKeySystemConfiguration>& aConfig);
+
+ private:
+  nsCOMPtr<nsPIDOMWindowInner> mParent;
+  const nsString mKeySystem;
+  const MediaKeySystemConfiguration mConfig;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_MediaKeySystemAccess_h
diff --git a/dom/media/eme/MediaKeySystemAccessManager.cpp b/dom/media/eme/MediaKeySystemAccessManager.cpp
new file mode 100644
index 0000000000..e6febfef54
--- /dev/null
+++ b/dom/media/eme/MediaKeySystemAccessManager.cpp
@@ -0,0 +1,684 @@
+/* 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 "MediaKeySystemAccessManager.h"
+
+#include "DecoderDoctorDiagnostics.h"
+#include "MediaKeySystemAccessPermissionRequest.h"
+#include "VideoUtils.h"
+#include "mozilla/dom/BrowserChild.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/DetailedPromise.h"
+#include "mozilla/EMEUtils.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/Services.h"
+#include "mozilla/StaticPrefs_media.h"
+#include "mozilla/Unused.h"
+#ifdef XP_WIN
+#  include "mozilla/WindowsVersion.h"
+#endif
+#ifdef XP_MACOSX
+#  include "nsCocoaFeatures.h"
+#endif
+#include "nsComponentManagerUtils.h"
+#include "nsContentUtils.h"
+#include "nsTHashMap.h"
+#include "nsIObserverService.h"
+#include "nsIScriptError.h"
+#include "nsPrintfCString.h"
+#include "nsServiceManagerUtils.h"
+
+namespace mozilla::dom {
+
+MediaKeySystemAccessManager::PendingRequest::PendingRequest(
+    DetailedPromise* aPromise, const nsAString& aKeySystem,
+    const Sequence<MediaKeySystemConfiguration>& aConfigs)
+    : mPromise(aPromise), mKeySystem(aKeySystem), mConfigs(aConfigs) {
+  MOZ_COUNT_CTOR(MediaKeySystemAccessManager::PendingRequest);
+}
+
+MediaKeySystemAccessManager::PendingRequest::~PendingRequest() {
+  MOZ_COUNT_DTOR(MediaKeySystemAccessManager::PendingRequest);
+}
+
+void MediaKeySystemAccessManager::PendingRequest::CancelTimer() {
+  if (mTimer) {
+    mTimer->Cancel();
+    mTimer = nullptr;
+  }
+}
+
+void MediaKeySystemAccessManager::PendingRequest::
+    RejectPromiseWithInvalidAccessError(const nsACString& aReason) {
+  if (mPromise) {
+    mPromise->MaybeRejectWithInvalidAccessError(aReason);
+  }
+}
+
+void MediaKeySystemAccessManager::PendingRequest::
+    RejectPromiseWithNotSupportedError(const nsACString& aReason) {
+  if (mPromise) {
+    mPromise->MaybeRejectWithNotSupportedError(aReason);
+  }
+}
+
+void MediaKeySystemAccessManager::PendingRequest::RejectPromiseWithTypeError(
+    const nsACString& aReason) {
+  if (mPromise) {
+    mPromise->MaybeRejectWithTypeError(aReason);
+  }
+}
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MediaKeySystemAccessManager)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIObserver)
+  NS_INTERFACE_MAP_ENTRY(nsIObserver)
+  NS_INTERFACE_MAP_ENTRY(nsINamed)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(MediaKeySystemAccessManager)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(MediaKeySystemAccessManager)
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(MediaKeySystemAccessManager)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(MediaKeySystemAccessManager)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mWindow)
+  for (size_t i = 0; i < tmp->mPendingInstallRequests.Length(); i++) {
+    tmp->mPendingInstallRequests[i]->CancelTimer();
+    tmp->mPendingInstallRequests[i]->RejectPromiseWithInvalidAccessError(
+        nsLiteralCString(
+            "Promise still outstanding at MediaKeySystemAccessManager GC"));
+    NS_IMPL_CYCLE_COLLECTION_UNLINK(mPendingInstallRequests[i]->mPromise)
+  }
+  tmp->mPendingInstallRequests.Clear();
+  for (size_t i = 0; i < tmp->mPendingAppApprovalRequests.Length(); i++) {
+    tmp->mPendingAppApprovalRequests[i]->RejectPromiseWithInvalidAccessError(
+        nsLiteralCString(
+            "Promise still outstanding at MediaKeySystemAccessManager GC"));
+    NS_IMPL_CYCLE_COLLECTION_UNLINK(mPendingAppApprovalRequests[i]->mPromise)
+  }
+  tmp->mPendingAppApprovalRequests.Clear();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(MediaKeySystemAccessManager)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mWindow)
+  for (size_t i = 0; i < tmp->mPendingInstallRequests.Length(); i++) {
+    NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPendingInstallRequests[i]->mPromise)
+  }
+  for (size_t i = 0; i < tmp->mPendingAppApprovalRequests.Length(); i++) {
+    NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPendingAppApprovalRequests[i]->mPromise)
+  }
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+#define MKSAM_LOG_DEBUG(msg, ...) \
+  EME_LOG("MediaKeySystemAccessManager::%s " msg, __func__, ##__VA_ARGS__)
+
+MediaKeySystemAccessManager::MediaKeySystemAccessManager(
+    nsPIDOMWindowInner* aWindow)
+    : mWindow(aWindow) {
+  MOZ_ASSERT(NS_IsMainThread());
+}
+
+MediaKeySystemAccessManager::~MediaKeySystemAccessManager() {
+  MOZ_ASSERT(NS_IsMainThread());
+  Shutdown();
+}
+
+void MediaKeySystemAccessManager::Request(
+    DetailedPromise* aPromise, const nsAString& aKeySystem,
+    const Sequence<MediaKeySystemConfiguration>& aConfigs) {
+  MOZ_ASSERT(NS_IsMainThread());
+  CheckDoesWindowSupportProtectedMedia(
+      MakeUnique<PendingRequest>(aPromise, aKeySystem, aConfigs));
+}
+
+void MediaKeySystemAccessManager::CheckDoesWindowSupportProtectedMedia(
+    UniquePtr<PendingRequest> aRequest) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aRequest);
+  MKSAM_LOG_DEBUG("aRequest->mKeySystem=%s",
+                  NS_ConvertUTF16toUTF8(aRequest->mKeySystem).get());
+
+  // In Windows OS, some Firefox windows that host content cannot support
+  // protected content, so check the status of support for this window.
+  // On other platforms windows should always support protected media.
+#ifdef XP_WIN
+  RefPtr<BrowserChild> browser(BrowserChild::GetFrom(mWindow));
+  if (!browser) {
+    if (!XRE_IsParentProcess() || XRE_IsE10sParentProcess()) {
+      // In this case, there is no browser because the Navigator object has
+      // been disconnected from its window. Thus, reject the promise.
+      aRequest->mPromise->MaybeRejectWithTypeError(
+          "Browsing context is no longer available");
+    } else {
+      // In this case, there is no browser because e10s is off. Proceed with
+      // the request with support since this scenario is always supported.
+      MKSAM_LOG_DEBUG("Allowing protected media on Windows with e10s off.");
+
+      OnDoesWindowSupportProtectedMedia(true, std::move(aRequest));
+    }
+
+    return;
+  }
+
+  RefPtr<MediaKeySystemAccessManager> self(this);
+
+  MKSAM_LOG_DEBUG(
+      "Checking with browser if this window supports protected media.");
+  browser->DoesWindowSupportProtectedMedia()->Then(
+      GetCurrentSerialEventTarget(), __func__,
+      [self, request = std::move(aRequest)](
+          const BrowserChild::IsWindowSupportingProtectedMediaPromise::
+              ResolveOrRejectValue& value) mutable {
+        if (value.IsResolve()) {
+          self->OnDoesWindowSupportProtectedMedia(value.ResolveValue(),
+                                                  std::move(request));
+        } else {
+          EME_LOG(
+              "MediaKeySystemAccessManager::DoesWindowSupportProtectedMedia-"
+              "ResolveOrRejectLambda Failed to make IPC call to "
+              "IsWindowSupportingProtectedMedia: "
+              "reason=%d",
+              static_cast<int>(value.RejectValue()));
+          // Treat as failure.
+          self->OnDoesWindowSupportProtectedMedia(false, std::move(request));
+        }
+      });
+
+#else
+  // Non-Windows OS windows always support protected media.
+  MKSAM_LOG_DEBUG(
+      "Allowing protected media because all non-Windows OS windows support "
+      "protected media.");
+  OnDoesWindowSupportProtectedMedia(true, std::move(aRequest));
+#endif
+}
+
+void MediaKeySystemAccessManager::OnDoesWindowSupportProtectedMedia(
+    bool aIsSupportedInWindow, UniquePtr<PendingRequest> aRequest) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aRequest);
+  MKSAM_LOG_DEBUG("aIsSupportedInWindow=%s aRequest->mKeySystem=%s",
+                  aIsSupportedInWindow ? "true" : "false",
+                  NS_ConvertUTF16toUTF8(aRequest->mKeySystem).get());
+
+  if (!aIsSupportedInWindow) {
+    aRequest->RejectPromiseWithNotSupportedError(
+        "EME is not supported in this window"_ns);
+    return;
+  }
+
+  RequestMediaKeySystemAccess(std::move(aRequest));
+}
+
+void MediaKeySystemAccessManager::CheckDoesAppAllowProtectedMedia(
+    UniquePtr<PendingRequest> aRequest) {
+  // At time of writing, only GeckoView is expected to leverage the need to
+  // approve EME requests from the application. However, this functionality
+  // can be tested on all platforms by manipulating the
+  // media.eme.require-app-approval + test prefs associated with
+  // MediaKeySystemPermissionRequest.
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aRequest);
+  MKSAM_LOG_DEBUG("aRequest->mKeySystem=%s",
+                  NS_ConvertUTF16toUTF8(aRequest->mKeySystem).get());
+
+  if (!StaticPrefs::media_eme_require_app_approval()) {
+    MKSAM_LOG_DEBUG(
+        "media.eme.require-app-approval is false, allowing request.");
+    // We don't require app approval as the pref is not set. Treat as app
+    // approving by passing true to the handler.
+    OnDoesAppAllowProtectedMedia(true, std::move(aRequest));
+    return;
+  }
+
+  if (mAppAllowsProtectedMediaPromiseRequest.Exists()) {
+    // We already have a pending permission request, we don't need to fire
+    // another. Just wait for the existing permission request to be handled
+    // and the result from that will be used to handle the current request.
+    MKSAM_LOG_DEBUG(
+        "mAppAllowsProtectedMediaPromiseRequest already exists. aRequest "
+        "addded to queue and will be handled when exising permission request "
+        "is serviced.");
+    mPendingAppApprovalRequests.AppendElement(std::move(aRequest));
+    return;
+  }
+
+  RefPtr<MediaKeySystemAccessPermissionRequest> appApprovalRequest =
+      MediaKeySystemAccessPermissionRequest::Create(mWindow);
+  if (!appApprovalRequest) {
+    MKSAM_LOG_DEBUG(
+        "Failed to create app approval request! Blocking eme request as "
+        "fallback.");
+    aRequest->RejectPromiseWithInvalidAccessError(nsLiteralCString(
+        "Failed to create approval request to send to app embedding Gecko."));
+    return;
+  }
+
+  // If we're not using testing prefs (which take precedence over cached
+  // values) and have a cached value, handle based on the cached value.
+  if (appApprovalRequest->CheckPromptPrefs() ==
+          MediaKeySystemAccessPermissionRequest::PromptResult::Pending &&
+      mAppAllowsProtectedMedia) {
+    MKSAM_LOG_DEBUG(
+        "Short circuiting based on mAppAllowsProtectedMedia cached value");
+    OnDoesAppAllowProtectedMedia(*mAppAllowsProtectedMedia,
+                                 std::move(aRequest));
+    return;
+  }
+
+  // Store the approval request, it will be handled when we get a response
+  // from the app.
+  mPendingAppApprovalRequests.AppendElement(std::move(aRequest));
+
+  RefPtr<MediaKeySystemAccessPermissionRequest::RequestPromise> p =
+      appApprovalRequest->GetPromise();
+  p->Then(
+       GetCurrentSerialEventTarget(), __func__,
+       // Allow callback
+       [this,
+        self = RefPtr<MediaKeySystemAccessManager>(this)](bool aRequestResult) {
+         MOZ_ASSERT(NS_IsMainThread());
+         MOZ_ASSERT(aRequestResult, "Result should be true on allow callback!");
+         mAppAllowsProtectedMediaPromiseRequest.Complete();
+         // Cache result.
+         mAppAllowsProtectedMedia = Some(aRequestResult);
+         // For each pending request, handle it based on the app's response.
+         for (UniquePtr<PendingRequest>& approvalRequest :
+              mPendingAppApprovalRequests) {
+           OnDoesAppAllowProtectedMedia(*mAppAllowsProtectedMedia,
+                                        std::move(approvalRequest));
+         }
+         self->mPendingAppApprovalRequests.Clear();
+       },
+       // Cancel callback
+       [this,
+        self = RefPtr<MediaKeySystemAccessManager>(this)](bool aRequestResult) {
+         MOZ_ASSERT(NS_IsMainThread());
+         MOZ_ASSERT(!aRequestResult,
+                    "Result should be false on cancel callback!");
+         mAppAllowsProtectedMediaPromiseRequest.Complete();
+         // Cache result.
+         mAppAllowsProtectedMedia = Some(aRequestResult);
+         // For each pending request, handle it based on the app's response.
+         for (UniquePtr<PendingRequest>& approvalRequest :
+              mPendingAppApprovalRequests) {
+           OnDoesAppAllowProtectedMedia(*mAppAllowsProtectedMedia,
+                                        std::move(approvalRequest));
+         }
+         self->mPendingAppApprovalRequests.Clear();
+       })
+      ->Track(mAppAllowsProtectedMediaPromiseRequest);
+
+  // Prefs not causing short circuit, no cached value, go ahead and request
+  // permission.
+  MKSAM_LOG_DEBUG("Dispatching async request for app approval");
+  if (NS_FAILED(appApprovalRequest->Start())) {
+    // This shouldn't happen unless we're shutting down or similar edge cases.
+    // If this is regularly being hit then something is wrong and should be
+    // investigated.
+    MKSAM_LOG_DEBUG(
+        "Failed to start app approval request! Eme approval will be left in "
+        "limbo!");
+  }
+}
+
+void MediaKeySystemAccessManager::OnDoesAppAllowProtectedMedia(
+    bool aIsAllowed, UniquePtr<PendingRequest> aRequest) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aRequest);
+  MKSAM_LOG_DEBUG("aIsAllowed=%s aRequest->mKeySystem=%s",
+                  aIsAllowed ? "true" : "false",
+                  NS_ConvertUTF16toUTF8(aRequest->mKeySystem).get());
+  if (!aIsAllowed) {
+    aRequest->RejectPromiseWithNotSupportedError(
+        nsLiteralCString("The application embedding this user agent has "
+                         "blocked MediaKeySystemAccess"));
+    return;
+  }
+
+  ProvideAccess(std::move(aRequest));
+}
+
+void MediaKeySystemAccessManager::RequestMediaKeySystemAccess(
+    UniquePtr<PendingRequest> aRequest) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aRequest);
+  MKSAM_LOG_DEBUG("aIsSupportedInWindow=%s",
+                  NS_ConvertUTF16toUTF8(aRequest->mKeySystem).get());
+
+  // 1. If keySystem is the empty string, return a promise rejected with a newly
+  // created TypeError.
+  if (aRequest->mKeySystem.IsEmpty()) {
+    aRequest->mPromise->MaybeRejectWithTypeError("Key system string is empty");
+    // Don't notify DecoderDoctor, as there's nothing we or the user can
+    // do to fix this situation; the site is using the API wrong.
+    return;
+  }
+  // 2. If supportedConfigurations is empty, return a promise rejected with a
+  // newly created TypeError.
+  if (aRequest->mConfigs.IsEmpty()) {
+    aRequest->mPromise->MaybeRejectWithTypeError(
+        "Candidate MediaKeySystemConfigs is empty");
+    // Don't notify DecoderDoctor, as there's nothing we or the user can
+    // do to fix this situation; the site is using the API wrong.
+    return;
+  }
+
+  // 3. Let document be the calling context's Document.
+  // 4. Let origin be the origin of document.
+  // 5. Let promise be a new promise.
+  // 6. Run the following steps in parallel:
+
+  DecoderDoctorDiagnostics diagnostics;
+
+  //   1. If keySystem is not one of the Key Systems supported by the user
+  //   agent, reject promise with a NotSupportedError. String comparison is
+  //   case-sensitive.
+  if (!IsWidevineKeySystem(aRequest->mKeySystem) &&
+#ifdef MOZ_WMF_CDM
+      !IsPlayReadyKeySystemAndSupported(aRequest->mKeySystem) &&
+#endif
+      !IsClearkeyKeySystem(aRequest->mKeySystem)) {
+    // Not to inform user, because nothing to do if the keySystem is not
+    // supported.
+    aRequest->RejectPromiseWithNotSupportedError(
+        "Key system is unsupported"_ns);
+    diagnostics.StoreMediaKeySystemAccess(
+        mWindow->GetExtantDoc(), aRequest->mKeySystem, false, __func__);
+    return;
+  }
+
+  if (!StaticPrefs::media_eme_enabled() &&
+      !IsClearkeyKeySystem(aRequest->mKeySystem)) {
+    // EME disabled by user, send notification to chrome so UI can inform user.
+    // Clearkey is allowed even when EME is disabled because we want the pref
+    // "media.eme.enabled" only taking effect on proprietary DRMs.
+    // We don't show the notification if the pref is locked.
+    if (!Preferences::IsLocked("media.eme.enabled")) {
+      MediaKeySystemAccess::NotifyObservers(mWindow, aRequest->mKeySystem,
+                                            MediaKeySystemStatus::Api_disabled);
+    }
+    aRequest->RejectPromiseWithNotSupportedError("EME has been preffed off"_ns);
+    diagnostics.StoreMediaKeySystemAccess(
+        mWindow->GetExtantDoc(), aRequest->mKeySystem, false, __func__);
+    return;
+  }
+
+  nsAutoCString message;
+  MediaKeySystemStatus status =
+      MediaKeySystemAccess::GetKeySystemStatus(aRequest->mKeySystem, message);
+
+  nsPrintfCString msg(
+      "MediaKeySystemAccess::GetKeySystemStatus(%s) "
+      "result=%s msg='%s'",
+      NS_ConvertUTF16toUTF8(aRequest->mKeySystem).get(),
+      nsCString(MediaKeySystemStatusValues::GetString(status)).get(),
+      message.get());
+  LogToBrowserConsole(NS_ConvertUTF8toUTF16(msg));
+
+  // We may need to install the CDM to continue.
+  if (status == MediaKeySystemStatus::Cdm_not_installed &&
+      IsWidevineKeySystem(aRequest->mKeySystem)) {
+    // These are cases which could be resolved by downloading a new(er) CDM.
+    // When we send the status to chrome, chrome's GMPProvider will attempt to
+    // download or update the CDM. In AwaitInstall() we add listeners to wait
+    // for the update to complete, and we'll call this function again with
+    // aType==Subsequent once the download has completed and the GMPService
+    // has had a new plugin added. AwaitInstall() sets a timer to fail if the
+    // update/download takes too long or fails.
+
+    if (aRequest->mRequestType != PendingRequest::RequestType::Initial) {
+      MOZ_ASSERT(aRequest->mRequestType ==
+                 PendingRequest::RequestType::Subsequent);
+      // CDM is not installed, but this is a subsequent request. We've waited,
+      // but can't service this request! Give up. Chrome will still be showing a
+      // "I can't play, updating" notification.
+      aRequest->RejectPromiseWithNotSupportedError(
+          "Timed out while waiting for a CDM update"_ns);
+      diagnostics.StoreMediaKeySystemAccess(
+          mWindow->GetExtantDoc(), aRequest->mKeySystem, false, __func__);
+      return;
+    }
+
+    const nsString keySystem = aRequest->mKeySystem;
+    if (AwaitInstall(std::move(aRequest))) {
+      // Notify chrome that we're going to wait for the CDM to download/update.
+      MediaKeySystemAccess::NotifyObservers(mWindow, keySystem, status);
+    } else {
+      // Failed to await the install. Log failure and give up trying to service
+      // this request.
+      diagnostics.StoreMediaKeySystemAccess(mWindow->GetExtantDoc(), keySystem,
+                                            false, __func__);
+    }
+    return;
+  }
+  if (status != MediaKeySystemStatus::Available) {
+    // Failed due to user disabling something, send a notification to
+    // chrome, so we can show some UI to explain how the user can rectify
+    // the situation.
+    MediaKeySystemAccess::NotifyObservers(mWindow, aRequest->mKeySystem,
+                                          status);
+    aRequest->RejectPromiseWithNotSupportedError(message);
+    return;
+  }
+
+  nsCOMPtr<Document> doc = mWindow->GetExtantDoc();
+  nsTHashMap<nsCharPtrHashKey, bool> warnings;
+  std::function<void(const char*)> deprecationWarningLogFn =
+      [&](const char* aMsgName) {
+        EME_LOG(
+            "MediaKeySystemAccessManager::DeprecationWarningLambda Logging "
+            "deprecation warning '%s' to WebConsole.",
+            aMsgName);
+        warnings.InsertOrUpdate(aMsgName, true);
+        AutoTArray<nsString, 1> params;
+        nsString& uri = *params.AppendElement();
+        if (doc) {
+          Unused << doc->GetDocumentURI(uri);
+        }
+        nsContentUtils::ReportToConsole(nsIScriptError::warningFlag, "Media"_ns,
+                                        doc, nsContentUtils::eDOM_PROPERTIES,
+                                        aMsgName, params);
+      };
+
+  bool isPrivateBrowsing =
+      mWindow->GetExtantDoc() &&
+      mWindow->GetExtantDoc()->NodePrincipal()->GetPrivateBrowsingId() > 0;
+  //   2. Let implementation be the implementation of keySystem.
+  //   3. For each value in supportedConfigurations:
+  //     1. Let candidate configuration be the value.
+  //     2. Let supported configuration be the result of executing the Get
+  //     Supported Configuration algorithm on implementation, candidate
+  //     configuration, and origin.
+  //     3. If supported configuration is not NotSupported, run the following
+  //     steps:
+  //       1. Let access be a new MediaKeySystemAccess object, and initialize it
+  //       as follows:
+  //         1. Set the keySystem attribute to keySystem.
+  //         2. Let the configuration value be supported configuration.
+  //         3. Let the cdm implementation value be implementation.
+  //      2. Resolve promise with access and abort the parallel steps of this
+  //      algorithm.
+  MediaKeySystemConfiguration config;
+  if (MediaKeySystemAccess::GetSupportedConfig(
+          aRequest->mKeySystem, aRequest->mConfigs, config, &diagnostics,
+          isPrivateBrowsing, deprecationWarningLogFn)) {
+    aRequest->mSupportedConfig = Some(config);
+    // The app gets the final say on if we provide access or not.
+    CheckDoesAppAllowProtectedMedia(std::move(aRequest));
+    return;
+  }
+  // 4. Reject promise with a NotSupportedError.
+
+  // Not to inform user, because nothing to do if the corresponding keySystem
+  // configuration is not supported.
+  aRequest->RejectPromiseWithNotSupportedError(
+      "Key system configuration is not supported"_ns);
+  diagnostics.StoreMediaKeySystemAccess(mWindow->GetExtantDoc(),
+                                        aRequest->mKeySystem, false, __func__);
+}
+
+void MediaKeySystemAccessManager::ProvideAccess(
+    UniquePtr<PendingRequest> aRequest) {
+  MOZ_ASSERT(aRequest);
+  MOZ_ASSERT(
+      aRequest->mSupportedConfig,
+      "The request needs a supported config if we're going to provide access!");
+  MKSAM_LOG_DEBUG("aRequest->mKeySystem=%s",
+                  NS_ConvertUTF16toUTF8(aRequest->mKeySystem).get());
+
+  DecoderDoctorDiagnostics diagnostics;
+
+  RefPtr<MediaKeySystemAccess> access(new MediaKeySystemAccess(
+      mWindow, aRequest->mKeySystem, aRequest->mSupportedConfig.ref()));
+  aRequest->mPromise->MaybeResolve(access);
+  diagnostics.StoreMediaKeySystemAccess(mWindow->GetExtantDoc(),
+                                        aRequest->mKeySystem, true, __func__);
+}
+
+bool MediaKeySystemAccessManager::AwaitInstall(
+    UniquePtr<PendingRequest> aRequest) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aRequest);
+  MKSAM_LOG_DEBUG("aRequest->mKeySystem=%s",
+                  NS_ConvertUTF16toUTF8(aRequest->mKeySystem).get());
+
+  if (!EnsureObserversAdded()) {
+    NS_WARNING("Failed to add pref observer");
+    aRequest->RejectPromiseWithNotSupportedError(nsLiteralCString(
+        "Failed trying to setup CDM update: failed adding observers"));
+    return false;
+  }
+
+  nsCOMPtr<nsITimer> timer;
+  NS_NewTimerWithObserver(getter_AddRefs(timer), this, 60 * 1000,
+                          nsITimer::TYPE_ONE_SHOT);
+  if (!timer) {
+    NS_WARNING("Failed to create timer to await CDM install.");
+    aRequest->RejectPromiseWithNotSupportedError(nsLiteralCString(
+        "Failed trying to setup CDM update: failed timer creation"));
+    return false;
+  }
+
+  MOZ_DIAGNOSTIC_ASSERT(
+      aRequest->mTimer == nullptr,
+      "Timer should not already be set on a request we're about to await");
+  aRequest->mTimer = timer;
+
+  mPendingInstallRequests.AppendElement(std::move(aRequest));
+  return true;
+}
+
+void MediaKeySystemAccessManager::RetryRequest(
+    UniquePtr<PendingRequest> aRequest) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aRequest);
+  MKSAM_LOG_DEBUG("aRequest->mKeySystem=%s",
+                  NS_ConvertUTF16toUTF8(aRequest->mKeySystem).get());
+  // Cancel and null timer if it exists.
+  aRequest->CancelTimer();
+  // Indicate that this is a request that's being retried.
+  aRequest->mRequestType = PendingRequest::RequestType::Subsequent;
+  RequestMediaKeySystemAccess(std::move(aRequest));
+}
+
+nsresult MediaKeySystemAccessManager::Observe(nsISupports* aSubject,
+                                              const char* aTopic,
+                                              const char16_t* aData) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MKSAM_LOG_DEBUG("%s", aTopic);
+
+  if (!strcmp(aTopic, "gmp-changed")) {
+    // Filter out the requests where the CDM's install-status is no longer
+    // "unavailable". This will be the CDMs which have downloaded since the
+    // initial request.
+    // Note: We don't have a way to communicate from chrome that the CDM has
+    // failed to download, so we'll just let the timeout fail us in that case.
+    nsTArray<UniquePtr<PendingRequest>> requests;
+    for (size_t i = mPendingInstallRequests.Length(); i-- > 0;) {
+      nsAutoCString message;
+      MediaKeySystemStatus status = MediaKeySystemAccess::GetKeySystemStatus(
+          mPendingInstallRequests[i]->mKeySystem, message);
+      if (status == MediaKeySystemStatus::Cdm_not_installed) {
+        // Not yet installed, don't retry. Keep waiting until timeout.
+        continue;
+      }
+      // Status has changed, retry request.
+      requests.AppendElement(std::move(mPendingInstallRequests[i]));
+      mPendingInstallRequests.RemoveElementAt(i);
+    }
+    // Retry all pending requests, but this time fail if the CDM is not
+    // installed.
+    for (size_t i = requests.Length(); i-- > 0;) {
+      RetryRequest(std::move(requests[i]));
+    }
+  } else if (!strcmp(aTopic, "timer-callback")) {
+    // Find the timer that expired and re-run the request for it.
+    nsCOMPtr<nsITimer> timer(do_QueryInterface(aSubject));
+    for (size_t i = 0; i < mPendingInstallRequests.Length(); i++) {
+      if (mPendingInstallRequests[i]->mTimer == timer) {
+        EME_LOG("MediaKeySystemAccessManager::AwaitInstall resuming request");
+        UniquePtr<PendingRequest> request =
+            std::move(mPendingInstallRequests[i]);
+        mPendingInstallRequests.RemoveElementAt(i);
+        RetryRequest(std::move(request));
+        break;
+      }
+    }
+  }
+  return NS_OK;
+}
+
+nsresult MediaKeySystemAccessManager::GetName(nsACString& aName) {
+  aName.AssignLiteral("MediaKeySystemAccessManager");
+  return NS_OK;
+}
+
+bool MediaKeySystemAccessManager::EnsureObserversAdded() {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mAddedObservers) {
+    return true;
+  }
+
+  nsCOMPtr<nsIObserverService> obsService =
+      mozilla::services::GetObserverService();
+  if (NS_WARN_IF(!obsService)) {
+    return false;
+  }
+  mAddedObservers =
+      NS_SUCCEEDED(obsService->AddObserver(this, "gmp-changed", false));
+  return mAddedObservers;
+}
+
+void MediaKeySystemAccessManager::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MKSAM_LOG_DEBUG("");
+  for (const UniquePtr<PendingRequest>& installRequest :
+       mPendingInstallRequests) {
+    // Cancel all requests; we're shutting down.
+    installRequest->CancelTimer();
+    installRequest->RejectPromiseWithInvalidAccessError(nsLiteralCString(
+        "Promise still outstanding at MediaKeySystemAccessManager shutdown"));
+  }
+  mPendingInstallRequests.Clear();
+  for (const UniquePtr<PendingRequest>& approvalRequest :
+       mPendingAppApprovalRequests) {
+    approvalRequest->RejectPromiseWithInvalidAccessError(nsLiteralCString(
+        "Promise still outstanding at MediaKeySystemAccessManager shutdown"));
+  }
+  mPendingAppApprovalRequests.Clear();
+  mAppAllowsProtectedMediaPromiseRequest.DisconnectIfExists();
+  if (mAddedObservers) {
+    nsCOMPtr<nsIObserverService> obsService =
+        mozilla::services::GetObserverService();
+    if (obsService) {
+      obsService->RemoveObserver(this, "gmp-changed");
+      mAddedObservers = false;
+    }
+  }
+}
+
+}  // namespace mozilla::dom
+
+#undef MKSAM_LOG_DEBUG
diff --git a/dom/media/eme/MediaKeySystemAccessManager.h b/dom/media/eme/MediaKeySystemAccessManager.h
new file mode 100644
index 0000000000..992de2a9e7
--- /dev/null
+++ b/dom/media/eme/MediaKeySystemAccessManager.h
@@ -0,0 +1,229 @@
+/* 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/. */
+
+#ifndef DOM_MEDIA_MEDIAKEYSYSTEMACCESSMANAGER_H_
+#define DOM_MEDIA_MEDIAKEYSYSTEMACCESSMANAGER_H_
+
+#include "mozilla/dom/MediaKeySystemAccess.h"
+#include "mozilla/MozPromise.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsIObserver.h"
+#include "nsISupportsImpl.h"
+#include "nsITimer.h"
+
+namespace mozilla::dom {
+
+class DetailedPromise;
+class TestGMPVideoDecoder;
+
+/**
+ * MediaKeySystemAccessManager implements the functionality for
+ * Navigator.requestMediaKeySystemAccess(). The navigator may perform its own
+ * logic before passing the request to this class, but the majority of
+ * processing happens the MediaKeySystemAccessManager. The manager is expected
+ * to be run entirely on the main thread of the content process for whichever
+ * window it is associated with.
+ *
+ * As well as implementing the Navigator.requestMediaKeySystemAccess()
+ * algorithm, the manager performs Gecko specific logic. For example, the EME
+ * specification does not specify a process to check if a CDM is installed as
+ * part of requesting access, but that is an important part of obtaining access
+ * for Gecko, and is handled by the manager.
+ *
+ * A request made to the manager can be thought of as entering a pipeline.
+ * In this pipeline the request must pass through various stages that can
+ * reject the request and remove it from the pipeline. If a request is not
+ * rejected by the end of the pipeline it is approved/resolved.
+ *
+ * The pipeline is structured in such a way that each step should be executed
+ * even if it will quickly be exited. For example, the step that checks if a
+ * window supports protected media is an instant approve on non-Windows OSes,
+ * but we want to execute the function representing that step to ensure a
+ * deterministic execution and logging path. The hope is this reduces
+ * complexity for when we need to debug or change the code.
+ *
+ * While the pipeline metaphor generally holds, the implementation details of
+ * the manager mean that processing is not always linear: a request may be
+ * re-injected earlier into the pipeline for reprocessing. This can happen
+ * if the request was pending some other operation, e.g. CDM install, after
+ * which we wish to reprocess that request. However, we strive to keep it
+ * as linear as possible.
+ *
+ * A high level version of the happy path pipeline is depicted below. If a
+ * request were to fail any of the steps below it would be rejected and ejected
+ * from the pipeline.
+ *
+ *       Request arrives from navigator
+ *                   +
+ *                   |
+ *                   v
+ *  Check if window supports protected media
+ *                   +
+ *                   +<-------------------+
+ *                   v                    |
+ *       Check request args are sane      |
+ *                   +                    |
+ *                   |           Wait for CDM and retry
+ *                   v                    |
+ *        Check if CDM is installed       |
+ *                   +                    |
+ *                   |                    |
+ *                   +--------------------+
+ *                   |
+ *                   v
+ *       Check if CDM supports args
+ *                   +
+ *                   |
+ *                   v
+ *    Check if app allows protected media
+ *           (used by GeckoView)
+ *                   +
+ *                   |
+ *                   v
+ *            Provide access
+ *
+ */
+
+class MediaKeySystemAccessManager final : public nsIObserver, public nsINamed {
+ public:
+  explicit MediaKeySystemAccessManager(nsPIDOMWindowInner* aWindow);
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(MediaKeySystemAccessManager,
+                                           nsIObserver)
+  NS_DECL_NSIOBSERVER
+  NS_DECL_NSINAMED
+
+  // Entry point for the navigator to call into the manager.
+  void Request(DetailedPromise* aPromise, const nsAString& aKeySystem,
+               const Sequence<MediaKeySystemConfiguration>& aConfig);
+
+  void Shutdown();
+
+ private:
+  // Encapsulates the information for a Navigator.requestMediaKeySystemAccess()
+  // request that is being processed.
+  struct PendingRequest {
+    enum class RequestType { Initial, Subsequent };
+
+    PendingRequest(DetailedPromise* aPromise, const nsAString& aKeySystem,
+                   const Sequence<MediaKeySystemConfiguration>& aConfigs);
+    ~PendingRequest();
+
+    // The JS promise associated with this request.
+    RefPtr<DetailedPromise> mPromise;
+    // The KeySystem passed for this request.
+    const nsString mKeySystem;
+    // The config(s) passed for this request.
+    const Sequence<MediaKeySystemConfiguration> mConfigs;
+
+    // If the request is
+    // - A first attempt request from JS: RequestType::Initial.
+    // - A request we're reprocessing due to a GMP being installed:
+    //   RequestType::Subsequent.
+    RequestType mRequestType = RequestType::Initial;
+
+    // If we find a supported config for this request during processing it
+    // should be stored here. Only if we have a supported config should a
+    // request have access provided.
+    Maybe<MediaKeySystemConfiguration> mSupportedConfig;
+
+    // Will be set to trigger a timeout and re-processing of the request if the
+    // request is pending on some potentially time consuming operation, e.g.
+    // CDM install.
+    nsCOMPtr<nsITimer> mTimer = nullptr;
+
+    // Convenience methods to reject the wrapped promise.
+    void RejectPromiseWithInvalidAccessError(const nsACString& aReason);
+    void RejectPromiseWithNotSupportedError(const nsACString& aReason);
+    void RejectPromiseWithTypeError(const nsACString& aReason);
+
+    void CancelTimer();
+  };
+
+  // Check if the application (e.g. a GeckoView app) allows protected media in
+  // this window.
+  //
+  // This function is always expected to be executed as part of the pipeline of
+  // processing a request, but its behavior differs depending on prefs set.
+  //
+  // If the `media_eme_require_app_approval` pref is false, then the function
+  // assumes app approval and early returns. Otherwise the function will
+  // create a permission request to be approved by the embedding app. If the
+  // test prefs detailed in MediaKeySystemAccessPermissionRequest.h are set
+  // then they will control handling, otherwise it is up to the embedding
+  // app to handle the request.
+  //
+  // At the time of writing, only GeckoView based apps are expected to pref
+  // on this behavior.
+  //
+  // This function is expected to run late/last in the pipeline so that if we
+  // ask the app for permission we don't fail after the app okays the request.
+  // This is to avoid cases where a user may be prompted by the app to approve
+  // eme, this check then passes, but we fail later in the pipeline, leaving
+  // the user wondering why their approval didn't work.
+  void CheckDoesAppAllowProtectedMedia(UniquePtr<PendingRequest> aRequest);
+
+  // Handles the result of the app allowing or disallowing protected media.
+  // If there are pending requests in mPendingAppApprovalRequests then this
+  // needs to be called on each.
+  void OnDoesAppAllowProtectedMedia(bool aIsAllowed,
+                                    UniquePtr<PendingRequest> aRequest);
+
+  // Checks if the Window associated with this manager supports protected media
+  // and calls into OnDoesWindowSupportEncryptedMedia with the result.
+  void CheckDoesWindowSupportProtectedMedia(UniquePtr<PendingRequest> aRequest);
+
+  // Handle the result of checking if the window associated with this manager
+  // supports protected media. If the window doesn't support protected media
+  // this will reject the request, otherwise the request will continue to be
+  // processed.
+  void OnDoesWindowSupportProtectedMedia(bool aIsSupportedInWindow,
+                                         UniquePtr<PendingRequest> aRequest);
+
+  // Performs the 'requestMediaKeySystemAccess' algorithm detailed in the EME
+  // specification. Gecko may need to install a CDM to satisfy this check. If
+  // CDM install is needed this function may be called again for the same
+  // request once the CDM is installed or a timeout is reached.
+  void RequestMediaKeySystemAccess(UniquePtr<PendingRequest> aRequest);
+
+  // Approves aRequest and provides MediaKeySystemAccess by resolving the
+  // promise associated with the request.
+  void ProvideAccess(UniquePtr<PendingRequest> aRequest);
+
+  ~MediaKeySystemAccessManager();
+
+  bool EnsureObserversAdded();
+
+  bool AwaitInstall(UniquePtr<PendingRequest> aRequest);
+
+  void RetryRequest(UniquePtr<PendingRequest> aRequest);
+
+  // Requests waiting on approval from the application to be processed.
+  nsTArray<UniquePtr<PendingRequest>> mPendingAppApprovalRequests;
+
+  // Requests waiting on CDM installation to be processed.
+  nsTArray<UniquePtr<PendingRequest>> mPendingInstallRequests;
+
+  nsCOMPtr<nsPIDOMWindowInner> mWindow;
+  bool mAddedObservers = false;
+
+  // Has the app approved protected media playback? If it has we cache the
+  // value so we don't need to check again.
+  Maybe<bool> mAppAllowsProtectedMedia;
+
+  // If we're waiting for permission from the app to enable EME this holder
+  // should contain the request.
+  //
+  // Note the type in the holder should match
+  // MediaKeySystemAccessPermissionRequest::RequestPromise, but we can't
+  // include MediaKeySystemAccessPermissionRequest's header here without
+  // breaking the build, so we do this hack.
+  MozPromiseRequestHolder<MozPromise<bool, bool, true>>
+      mAppAllowsProtectedMediaPromiseRequest;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // DOM_MEDIA_MEDIAKEYSYSTEMACCESSMANAGER_H_
diff --git a/dom/media/eme/MediaKeySystemAccessPermissionRequest.cpp b/dom/media/eme/MediaKeySystemAccessPermissionRequest.cpp
new file mode 100644
index 0000000000..063bf93f7e
--- /dev/null
+++ b/dom/media/eme/MediaKeySystemAccessPermissionRequest.cpp
@@ -0,0 +1,91 @@
+/* -*- 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 "MediaKeySystemAccessPermissionRequest.h"
+
+#include "nsGlobalWindowInner.h"
+
+namespace mozilla::dom {
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(MediaKeySystemAccessPermissionRequest,
+                                   ContentPermissionRequestBase)
+
+NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED_0(
+    MediaKeySystemAccessPermissionRequest, ContentPermissionRequestBase)
+
+/* static */
+already_AddRefed<MediaKeySystemAccessPermissionRequest>
+MediaKeySystemAccessPermissionRequest::Create(nsPIDOMWindowInner* aWindow) {
+  // Could conceivably be created off main thread then used on main thread
+  // later. If we really need to do that at some point we could relax this
+  // assert.
+  AssertIsOnMainThread();
+  if (!aWindow) {
+    return nullptr;
+  }
+
+  nsGlobalWindowInner* innerWindow = nsGlobalWindowInner::Cast(aWindow);
+  if (!innerWindow->GetPrincipal()) {
+    return nullptr;
+  }
+
+  RefPtr<MediaKeySystemAccessPermissionRequest> request =
+      new MediaKeySystemAccessPermissionRequest(innerWindow);
+  return request.forget();
+}
+
+MediaKeySystemAccessPermissionRequest::MediaKeySystemAccessPermissionRequest(
+    nsGlobalWindowInner* aWindow)
+    : ContentPermissionRequestBase(aWindow->GetPrincipal(), aWindow,
+                                   "media.eme.require-app-approval"_ns,
+                                   "media-key-system-access"_ns) {}
+
+MediaKeySystemAccessPermissionRequest::
+    ~MediaKeySystemAccessPermissionRequest() {
+  AssertIsOnMainThread();
+  // If a request has not been serviced by the time it is destroyed, treat it
+  // as if the request was denied.
+  Cancel();
+}
+
+already_AddRefed<MediaKeySystemAccessPermissionRequest::RequestPromise>
+MediaKeySystemAccessPermissionRequest::GetPromise() {
+  return mPromiseHolder.Ensure(__func__);
+}
+
+nsresult MediaKeySystemAccessPermissionRequest::Start() {
+  // Check test prefs to see if we should short circuit. We want to do this
+  // before checking the cached value so we can have pref changes take effect
+  // without refreshing the page.
+  MediaKeySystemAccessPermissionRequest::PromptResult promptResult =
+      CheckPromptPrefs();
+  if (promptResult ==
+      MediaKeySystemAccessPermissionRequest::PromptResult::Granted) {
+    return Allow(JS::UndefinedHandleValue);
+  }
+  if (promptResult ==
+      MediaKeySystemAccessPermissionRequest::PromptResult::Denied) {
+    return Cancel();
+  }
+
+  return nsContentPermissionUtils::AskPermission(this, mWindow);
+}
+
+NS_IMETHODIMP
+MediaKeySystemAccessPermissionRequest::Allow(JS::Handle<JS::Value> aChoices) {
+  AssertIsOnMainThread();
+  mPromiseHolder.ResolveIfExists(true, __func__);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+MediaKeySystemAccessPermissionRequest::Cancel() {
+  AssertIsOnMainThread();
+  mPromiseHolder.RejectIfExists(false, __func__);
+  return NS_OK;
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/media/eme/MediaKeySystemAccessPermissionRequest.h b/dom/media/eme/MediaKeySystemAccessPermissionRequest.h
new file mode 100644
index 0000000000..088cf50ab6
--- /dev/null
+++ b/dom/media/eme/MediaKeySystemAccessPermissionRequest.h
@@ -0,0 +1,74 @@
+/* -*- 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/. */
+
+#ifndef DOM_MEDIA_EME_MEDIAKEYSYSTEMACCESSPERMISSIONREQUEST_H_
+#define DOM_MEDIA_EME_MEDIAKEYSYSTEMACCESSPERMISSIONREQUEST_H_
+
+#include "mozilla/MozPromise.h"
+#include "nsContentPermissionHelper.h"
+
+class nsGlobalWindowInner;
+
+namespace mozilla::dom {
+
+/**
+ * This class encapsulates a permission request to allow media key system
+ * access. The intention is not for this class to be used in all cases of EME,
+ * but only when we need to seek explicit approval from an application using
+ * Gecko, such as an application embedding via GeckoView.
+ *
+ * media.eme.require-app-approval should be used to gate this functionality in
+ * gecko code, and is also used as the testing pref for
+ * ContentPermissionRequestBase. I.e. CheckPromptPrefs() will respond to having
+ * `media.eme.require-app-approval.prompt.testing` and
+ * `media.eme.require-app-approval.prompt.testing.allow` being set to true or
+ * false and will return an appropriate value to allow for test code to short
+ * circuit showing a prompt. Note that the code using this class needs to call
+ * CheckPromptPrefs and implement test specific logic, it is *not* handled by
+ * this class or ContentPermissionRequestBase.
+ *
+ * Expects to be used on main thread as ContentPermissionRequestBase uses
+ * PContentPermissionRequest which is managed by PContent which is main thread
+ * to main thread communication.
+ */
+class MediaKeySystemAccessPermissionRequest
+    : public ContentPermissionRequestBase {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(
+      MediaKeySystemAccessPermissionRequest, ContentPermissionRequestBase)
+
+  using RequestPromise = MozPromise<bool, bool, true /* IsExclusive*/>;
+
+  // Create a MediaKeySystemAccessPermissionRequest.
+  // @param aWindow The window associated with this request.
+  static already_AddRefed<MediaKeySystemAccessPermissionRequest> Create(
+      nsPIDOMWindowInner* aWindow);
+
+  // Returns a promise that will be resolved if this request is allowed or
+  // rejected in the case the request is denied. If allowed the promise
+  // will resolve with true, otherwise it will resolve with false.
+  already_AddRefed<RequestPromise> GetPromise();
+
+  // Helper function that triggers the request. This function will check
+  // prefs and cancel or allow the request if the appropriate prefs are set,
+  // otherwise it will fire the request to the associated window.
+  nsresult Start();
+
+  // nsIContentPermissionRequest methods
+  NS_IMETHOD Cancel(void) override;
+  NS_IMETHOD Allow(JS::Handle<JS::Value> choices) override;
+
+ private:
+  explicit MediaKeySystemAccessPermissionRequest(nsGlobalWindowInner* aWindow);
+  ~MediaKeySystemAccessPermissionRequest();
+
+  MozPromiseHolder<RequestPromise> mPromiseHolder;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // DOM_MEDIA_EME_MEDIAKEYSYSTEMACCESSPERMISSIONREQUEST_H_
diff --git a/dom/media/eme/MediaKeys.cpp b/dom/media/eme/MediaKeys.cpp
new file mode 100644
index 0000000000..0b256650a2
--- /dev/null
+++ b/dom/media/eme/MediaKeys.cpp
@@ -0,0 +1,844 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/MediaKeys.h"
+
+#include "ChromiumCDMProxy.h"
+#include "GMPCrashHelper.h"
+#include "mozilla/EMEUtils.h"
+#include "mozilla/JSONStringWriteFuncs.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/dom/DOMException.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/HTMLMediaElement.h"
+#include "mozilla/dom/MediaKeyError.h"
+#include "mozilla/dom/MediaKeyMessageEvent.h"
+#include "mozilla/dom/MediaKeySession.h"
+#include "mozilla/dom/MediaKeyStatusMap.h"
+#include "mozilla/dom/MediaKeySystemAccess.h"
+#include "mozilla/dom/MediaKeysBinding.h"
+#include "mozilla/dom/UnionTypes.h"
+#include "mozilla/dom/WindowContext.h"
+#include "mozilla/dom/WindowGlobalChild.h"
+#include "nsContentCID.h"
+#include "nsContentTypeParser.h"
+#include "nsContentUtils.h"
+#include "nsIScriptObjectPrincipal.h"
+#include "nsPrintfCString.h"
+#include "nsServiceManagerUtils.h"
+
+#ifdef MOZ_WIDGET_ANDROID
+#  include "mozilla/MediaDrmCDMProxy.h"
+#endif
+#ifdef XP_WIN
+#  include "mozilla/WindowsVersion.h"
+#endif
+#ifdef MOZ_WMF_CDM
+#  include "mozilla/WMFCDMProxy.h"
+#endif
+
+namespace mozilla::dom {
+
+// We don't use NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE because we need to
+// disconnect our MediaKeys instances from the inner window (mparent) before
+// we unlink it.
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(MediaKeys)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(MediaKeys)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mElement)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mParent)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mKeySessions)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPromises)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPendingSessions)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(MediaKeys)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mElement)
+  tmp->DisconnectInnerWindow();
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mParent)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mKeySessions)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mPromises)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mPendingSessions)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_WEAK_PTR
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(MediaKeys)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(MediaKeys)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MediaKeys)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+  NS_INTERFACE_MAP_ENTRY(nsIObserver)
+NS_INTERFACE_MAP_END
+
+MediaKeys::MediaKeys(nsPIDOMWindowInner* aParent, const nsAString& aKeySystem,
+                     const MediaKeySystemConfiguration& aConfig)
+    : mParent(aParent),
+      mKeySystem(aKeySystem),
+      mCreatePromiseId(0),
+      mConfig(aConfig) {
+  EME_LOG("MediaKeys[%p] constructed keySystem=%s", this,
+          NS_ConvertUTF16toUTF8(mKeySystem).get());
+}
+
+MediaKeys::~MediaKeys() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  DisconnectInnerWindow();
+  Shutdown();
+  EME_LOG("MediaKeys[%p] destroyed", this);
+}
+
+NS_IMETHODIMP MediaKeys::Observe(nsISupports* aSubject, const char* aTopic,
+                                 const char16_t* aData) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!strcmp(aTopic, kMediaKeysResponseTopic),
+             "Should only listen for responses to MediaKey requests");
+  EME_LOG("MediaKeys[%p] observing message with aTopic=%s aData=%s", this,
+          aTopic, NS_ConvertUTF16toUTF8(aData).get());
+  if (!strcmp(aTopic, kMediaKeysResponseTopic)) {
+    if (!mProxy) {
+      // This may happen if we're notified during shutdown or startup. If this
+      // is happening outside of those scenarios there's a bug.
+      EME_LOG(
+          "MediaKeys[%p] can't notify CDM of observed message as mProxy is "
+          "unset",
+          this);
+      return NS_OK;
+    }
+
+    if (u"capture-possible"_ns.Equals(aData)) {
+      mProxy->NotifyOutputProtectionStatus(
+          CDMProxy::OutputProtectionCheckStatus::CheckSuccessful,
+          CDMProxy::OutputProtectionCaptureStatus::CapturePossilbe);
+    } else if (u"capture-not-possible"_ns.Equals(aData)) {
+      mProxy->NotifyOutputProtectionStatus(
+          CDMProxy::OutputProtectionCheckStatus::CheckSuccessful,
+          CDMProxy::OutputProtectionCaptureStatus::CaptureNotPossible);
+    } else {
+      MOZ_ASSERT_UNREACHABLE("No code paths should lead to the failure case");
+      // This should be unreachable, but gracefully handle in case.
+      mProxy->NotifyOutputProtectionStatus(
+          CDMProxy::OutputProtectionCheckStatus::CheckFailed,
+          CDMProxy::OutputProtectionCaptureStatus::Unused);
+    }
+  }
+  return NS_OK;
+}
+
+void MediaKeys::ConnectInnerWindow() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  nsCOMPtr<nsPIDOMWindowInner> innerWindowParent = GetParentObject();
+  MOZ_ASSERT(innerWindowParent,
+             "We should only be connecting when we have an inner window!");
+  innerWindowParent->AddMediaKeysInstance(this);
+}
+
+void MediaKeys::DisconnectInnerWindow() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!GetParentObject()) {
+    // We don't have a parent. We've been cycle collected, or the window
+    // already notified us of its destruction and we cleared the ref.
+    return;
+  }
+
+  GetParentObject()->RemoveMediaKeysInstance(this);
+}
+
+void MediaKeys::OnInnerWindowDestroy() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  EME_LOG("MediaKeys[%p] OnInnerWindowDestroy()", this);
+
+  // The InnerWindow should clear its reference to this object after this call,
+  // so we don't need to explicitly call DisconnectInnerWindow before nulling.
+  mParent = nullptr;
+
+  // Don't call shutdown directly because (at time of writing) mProxy can
+  // spin the event loop when it's shutdown. This can change the world state
+  // in the middle of window destruction, which we do not want.
+  GetMainThreadSerialEventTarget()->Dispatch(
+      NewRunnableMethod("MediaKeys::Shutdown", this, &MediaKeys::Shutdown));
+}
+
+void MediaKeys::Terminated() {
+  EME_LOG("MediaKeys[%p] CDM crashed unexpectedly", this);
+
+  KeySessionHashMap keySessions;
+  // Remove entries during iteration will screw it. Make a copy first.
+  for (const RefPtr<MediaKeySession>& session : mKeySessions.Values()) {
+    // XXX Could the RefPtr still be moved here?
+    keySessions.InsertOrUpdate(session->GetSessionId(), RefPtr{session});
+  }
+  for (const RefPtr<MediaKeySession>& session : keySessions.Values()) {
+    session->OnClosed();
+  }
+  keySessions.Clear();
+  MOZ_ASSERT(mKeySessions.Count() == 0);
+
+  // Notify the element about that CDM has terminated.
+  if (mElement) {
+    mElement->DecodeError(NS_ERROR_DOM_MEDIA_CDM_ERR);
+  }
+
+  Shutdown();
+}
+
+void MediaKeys::Shutdown() {
+  EME_LOG("MediaKeys[%p]::Shutdown()", this);
+  if (mProxy) {
+    mProxy->Shutdown();
+    mProxy = nullptr;
+  }
+
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (observerService && mObserverAdded) {
+    observerService->RemoveObserver(this, kMediaKeysResponseTopic);
+  }
+
+  // Hold a self reference to keep us alive after we clear the self reference
+  // for each promise. This ensures we stay alive until we're done shutting
+  // down.
+  RefPtr<MediaKeys> selfReference = this;
+
+  for (const RefPtr<dom::DetailedPromise>& promise : mPromises.Values()) {
+    promise->MaybeRejectWithInvalidStateError(
+        "Promise still outstanding at MediaKeys shutdown");
+    Release();
+  }
+  mPromises.Clear();
+}
+
+nsPIDOMWindowInner* MediaKeys::GetParentObject() const { return mParent; }
+
+JSObject* MediaKeys::WrapObject(JSContext* aCx,
+                                JS::Handle<JSObject*> aGivenProto) {
+  return MediaKeys_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+void MediaKeys::GetKeySystem(nsString& aOutKeySystem) const {
+  aOutKeySystem.Assign(mKeySystem);
+}
+
+already_AddRefed<DetailedPromise> MediaKeys::SetServerCertificate(
+    const ArrayBufferViewOrArrayBuffer& aCert, ErrorResult& aRv) {
+  RefPtr<DetailedPromise> promise(
+      MakePromise(aRv, "MediaKeys.setServerCertificate"_ns));
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  if (!mProxy) {
+    NS_WARNING("Tried to use a MediaKeys without a CDM");
+    promise->MaybeRejectWithInvalidStateError(
+        "Null CDM in MediaKeys.setServerCertificate()");
+    return promise.forget();
+  }
+
+  nsTArray<uint8_t> data;
+  CopyArrayBufferViewOrArrayBufferData(aCert, data);
+  if (data.IsEmpty()) {
+    promise->MaybeRejectWithTypeError(
+        "Empty certificate passed to MediaKeys.setServerCertificate()");
+    return promise.forget();
+  }
+
+  mProxy->SetServerCertificate(StorePromise(promise), data);
+  return promise.forget();
+}
+
+already_AddRefed<DetailedPromise> MediaKeys::MakePromise(
+    ErrorResult& aRv, const nsACString& aName) {
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(GetParentObject());
+  if (!global) {
+    NS_WARNING("Passed non-global to MediaKeys ctor!");
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+  return DetailedPromise::Create(global, aRv, aName);
+}
+
+PromiseId MediaKeys::StorePromise(DetailedPromise* aPromise) {
+  static uint32_t sEMEPromiseCount = 1;
+  MOZ_ASSERT(aPromise);
+  uint32_t id = sEMEPromiseCount++;
+
+  EME_LOG("MediaKeys[%p]::StorePromise() id=%" PRIu32, this, id);
+
+  // Keep MediaKeys alive for the lifetime of its promises. Any still-pending
+  // promises are rejected in Shutdown().
+  EME_LOG("MediaKeys[%p]::StorePromise() calling AddRef()", this);
+  AddRef();
+
+#ifdef DEBUG
+  // We should not have already stored this promise!
+  for (const RefPtr<dom::DetailedPromise>& promise : mPromises.Values()) {
+    MOZ_ASSERT(promise != aPromise);
+  }
+#endif
+
+  mPromises.InsertOrUpdate(id, RefPtr{aPromise});
+  return id;
+}
+
+void MediaKeys::ConnectPendingPromiseIdWithToken(PromiseId aId,
+                                                 uint32_t aToken) {
+  // Should only be called from MediaKeySession::GenerateRequest.
+  mPromiseIdToken.InsertOrUpdate(aId, aToken);
+  EME_LOG(
+      "MediaKeys[%p]::ConnectPendingPromiseIdWithToken() id=%u => token(%u)",
+      this, aId, aToken);
+}
+
+already_AddRefed<DetailedPromise> MediaKeys::RetrievePromise(PromiseId aId) {
+  EME_LOG("MediaKeys[%p]::RetrievePromise(aId=%" PRIu32 ")", this, aId);
+  if (!mPromises.Contains(aId)) {
+    EME_LOG("MediaKeys[%p]::RetrievePromise(aId=%" PRIu32
+            ") tried to retrieve non-existent promise!",
+            this, aId);
+    NS_WARNING(nsPrintfCString(
+                   "Tried to retrieve a non-existent promise id=%" PRIu32, aId)
+                   .get());
+    return nullptr;
+  }
+  RefPtr<DetailedPromise> promise;
+  mPromises.Remove(aId, getter_AddRefs(promise));
+  EME_LOG("MediaKeys[%p]::RetrievePromise(aId=%" PRIu32 ") calling Release()",
+          this, aId);
+  Release();
+  return promise.forget();
+}
+
+void MediaKeys::RejectPromise(PromiseId aId, ErrorResult&& aException,
+                              const nsCString& aReason) {
+  uint32_t errorCodeAsInt = aException.ErrorCodeAsInt();
+  EME_LOG("MediaKeys[%p]::RejectPromise(%" PRIu32 ", 0x%" PRIx32 ")", this, aId,
+          errorCodeAsInt);
+
+  RefPtr<DetailedPromise> promise(RetrievePromise(aId));
+  if (!promise) {
+    EME_LOG("MediaKeys[%p]::RejectPromise(%" PRIu32 ", 0x%" PRIx32
+            ") couldn't retrieve promise! Bailing!",
+            this, aId, errorCodeAsInt);
+    return;
+  }
+
+  // This promise could be a createSession or loadSession promise,
+  // so we might have a pending session waiting to be resolved into
+  // the promise on success. We've been directed to reject to promise,
+  // so we can throw away the corresponding session object.
+  uint32_t token = 0;
+  if (mPromiseIdToken.Get(aId, &token)) {
+    MOZ_ASSERT(mPendingSessions.Contains(token));
+    mPendingSessions.Remove(token);
+    mPromiseIdToken.Remove(aId);
+  }
+
+  MOZ_ASSERT(aException.Failed());
+  promise->MaybeReject(std::move(aException), aReason);
+
+  if (mCreatePromiseId == aId) {
+    // Note: This will probably destroy the MediaKeys object!
+    EME_LOG("MediaKeys[%p]::RejectPromise(%" PRIu32 ", 0x%" PRIx32
+            ") calling Release()",
+            this, aId, errorCodeAsInt);
+    Release();
+  }
+}
+
+void MediaKeys::OnSessionIdReady(MediaKeySession* aSession) {
+  if (!aSession) {
+    NS_WARNING("Invalid MediaKeySession passed to OnSessionIdReady()");
+    return;
+  }
+  if (mKeySessions.Contains(aSession->GetSessionId())) {
+    NS_WARNING("MediaKeySession's made ready multiple times!");
+    return;
+  }
+  if (mPendingSessions.Contains(aSession->Token())) {
+    NS_WARNING(
+        "MediaKeySession made ready when it wasn't waiting to be ready!");
+    return;
+  }
+  if (aSession->GetSessionId().IsEmpty()) {
+    NS_WARNING(
+        "MediaKeySession with invalid sessionId passed to OnSessionIdReady()");
+    return;
+  }
+  mKeySessions.InsertOrUpdate(aSession->GetSessionId(), RefPtr{aSession});
+}
+
+void MediaKeys::ResolvePromise(PromiseId aId) {
+  EME_LOG("MediaKeys[%p]::ResolvePromise(%" PRIu32 ")", this, aId);
+
+  RefPtr<DetailedPromise> promise(RetrievePromise(aId));
+  MOZ_ASSERT(!mPromises.Contains(aId));
+  if (!promise) {
+    return;
+  }
+
+  uint32_t token = 0;
+  if (!mPromiseIdToken.Get(aId, &token)) {
+    promise->MaybeResolveWithUndefined();
+    return;
+  } else if (!mPendingSessions.Contains(token)) {
+    // Pending session for CreateSession() should be removed when sessionId
+    // is ready.
+    promise->MaybeResolveWithUndefined();
+    mPromiseIdToken.Remove(aId);
+    return;
+  }
+  mPromiseIdToken.Remove(aId);
+
+  // We should only resolve LoadSession calls via this path,
+  // not CreateSession() promises.
+  RefPtr<MediaKeySession> session;
+  mPendingSessions.Remove(token, getter_AddRefs(session));
+  if (!session || session->GetSessionId().IsEmpty()) {
+    NS_WARNING("Received activation for non-existent session!");
+    promise->MaybeRejectWithInvalidAccessError(
+        "CDM LoadSession() returned a different session ID than requested");
+    return;
+  }
+  mKeySessions.InsertOrUpdate(session->GetSessionId(), RefPtr{session});
+  promise->MaybeResolve(session);
+}
+
+class MediaKeysGMPCrashHelper : public GMPCrashHelper {
+ public:
+  explicit MediaKeysGMPCrashHelper(MediaKeys* aMediaKeys)
+      : mMediaKeys(aMediaKeys) {
+    MOZ_ASSERT(NS_IsMainThread());  // WeakPtr isn't thread safe.
+  }
+  already_AddRefed<nsPIDOMWindowInner> GetPluginCrashedEventTarget() override {
+    MOZ_ASSERT(NS_IsMainThread());  // WeakPtr isn't thread safe.
+    EME_LOG("MediaKeysGMPCrashHelper::GetPluginCrashedEventTarget()");
+    return (mMediaKeys && mMediaKeys->GetParentObject())
+               ? do_AddRef(mMediaKeys->GetParentObject())
+               : nullptr;
+  }
+
+ private:
+  WeakPtr<MediaKeys> mMediaKeys;
+};
+
+already_AddRefed<CDMProxy> MediaKeys::CreateCDMProxy() {
+  EME_LOG("MediaKeys[%p]::CreateCDMProxy()", this);
+  RefPtr<CDMProxy> proxy;
+#ifdef MOZ_WIDGET_ANDROID
+  if (IsWidevineKeySystem(mKeySystem)) {
+    proxy = new MediaDrmCDMProxy(
+        this, mKeySystem,
+        mConfig.mDistinctiveIdentifier == MediaKeysRequirement::Required,
+        mConfig.mPersistentState == MediaKeysRequirement::Required);
+  } else
+#endif
+#ifdef MOZ_WMF_CDM
+      if (IsPlayReadyKeySystemAndSupported(mKeySystem)) {
+    proxy = new WMFCDMProxy(this, mKeySystem, mConfig);
+  } else
+#endif
+  {
+    proxy = new ChromiumCDMProxy(
+        this, mKeySystem, new MediaKeysGMPCrashHelper(this),
+        mConfig.mDistinctiveIdentifier == MediaKeysRequirement::Required,
+        mConfig.mPersistentState == MediaKeysRequirement::Required);
+  }
+  return proxy.forget();
+}
+
+already_AddRefed<DetailedPromise> MediaKeys::Init(ErrorResult& aRv) {
+  EME_LOG("MediaKeys[%p]::Init()", this);
+  RefPtr<DetailedPromise> promise(MakePromise(aRv, "MediaKeys::Init()"_ns));
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // Determine principal (at creation time) of the MediaKeys object.
+  nsCOMPtr<nsIScriptObjectPrincipal> sop = do_QueryInterface(GetParentObject());
+  if (!sop) {
+    promise->MaybeRejectWithInvalidStateError(
+        "Couldn't get script principal in MediaKeys::Init");
+    return promise.forget();
+  }
+  mPrincipal = sop->GetPrincipal();
+
+  // Begin figuring out the top level principal.
+  nsCOMPtr<nsPIDOMWindowInner> window = GetParentObject();
+
+  // If we're in a top level document, getting the top level principal is easy.
+  // However, we're not in a top level doc this becomes more complicated. If
+  // we're not top level we need to get the top level principal, this can be
+  // done by reading the principal of the load info, which we can get of a
+  // document's channel.
+  //
+  // There is an edge case we need to watch out for here where this code can be
+  // run in an about:blank document before it has done its async load. In this
+  // case the document will not yet have a load info. We address this below by
+  // walking up a level in the window context chain. See
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=1675360
+  // for more info.
+  Document* document = window->GetExtantDoc();
+  if (!document) {
+    NS_WARNING("Failed to get document when creating MediaKeys");
+    promise->MaybeRejectWithInvalidStateError(
+        "Couldn't get document in MediaKeys::Init");
+    return promise.forget();
+  }
+
+  WindowGlobalChild* windowGlobalChild = window->GetWindowGlobalChild();
+  if (!windowGlobalChild) {
+    NS_WARNING("Failed to get window global child when creating MediaKeys");
+    promise->MaybeRejectWithInvalidStateError(
+        "Couldn't get window global child in MediaKeys::Init");
+    return promise.forget();
+  }
+
+  if (windowGlobalChild->SameOriginWithTop()) {
+    // We're in the same origin as the top window context, so our principal
+    // is also the top principal.
+    mTopLevelPrincipal = mPrincipal;
+  } else {
+    // We have a different origin than the top doc, try and find the top level
+    // principal by looking it up via load info, which we read off a channel.
+    nsIChannel* channel = document->GetChannel();
+
+    WindowContext* windowContext = document->GetWindowContext();
+    if (!windowContext) {
+      NS_WARNING("Failed to get window context when creating MediaKeys");
+      promise->MaybeRejectWithInvalidStateError(
+          "Couldn't get window context in MediaKeys::Init");
+      return promise.forget();
+    }
+    while (!channel) {
+      // We don't have a channel, this can happen if we're in an about:blank
+      // page that hasn't yet had its async load performed. Try and get
+      // the channel from our parent doc. We should be able to do this because
+      // an about:blank is considered the same origin as its parent. We do this
+      // recursively to cover pages do silly things like nesting blank iframes
+      // and not waiting for loads.
+
+      // Move our window context up a level.
+      windowContext = windowContext->GetParentWindowContext();
+      if (!windowContext || !windowContext->GetExtantDoc()) {
+        NS_WARNING(
+            "Failed to get parent window context's document when creating "
+            "MediaKeys");
+        promise->MaybeRejectWithInvalidStateError(
+            "Couldn't get parent window context's document in "
+            "MediaKeys::Init (likely due to an nested about about:blank frame "
+            "that hasn't loaded yet)");
+        return promise.forget();
+      }
+
+      Document* parentDoc = windowContext->GetExtantDoc();
+      channel = parentDoc->GetChannel();
+    }
+
+    MOZ_RELEASE_ASSERT(
+        channel, "Should either have a channel or should have returned by now");
+
+    nsCOMPtr<nsILoadInfo> loadInfo = channel->LoadInfo();
+    MOZ_RELEASE_ASSERT(loadInfo, "Channels should always have LoadInfo");
+    mTopLevelPrincipal = loadInfo->GetTopLevelPrincipal();
+    if (!mTopLevelPrincipal) {
+      NS_WARNING("Failed to get top level principal when creating MediaKeys");
+      promise->MaybeRejectWithInvalidStateError(
+          "Couldn't get top level principal in MediaKeys::Init");
+      return promise.forget();
+    }
+  }
+
+  // We should have figured out our top level principal.
+  if (!mPrincipal || !mTopLevelPrincipal) {
+    NS_WARNING("Failed to get principals when creating MediaKeys");
+    promise->MaybeRejectWithInvalidStateError(
+        "Couldn't get principal(s) in MediaKeys::Init");
+    return promise.forget();
+  }
+
+  nsAutoCString origin;
+  nsresult rv = mPrincipal->GetOrigin(origin);
+  if (NS_FAILED(rv)) {
+    promise->MaybeRejectWithInvalidStateError(
+        "Couldn't get principal origin string in MediaKeys::Init");
+    return promise.forget();
+  }
+  nsAutoCString topLevelOrigin;
+  rv = mTopLevelPrincipal->GetOrigin(topLevelOrigin);
+  if (NS_FAILED(rv)) {
+    promise->MaybeRejectWithInvalidStateError(
+        "Couldn't get top-level principal origin string in MediaKeys::Init");
+    return promise.forget();
+  }
+
+  EME_LOG("MediaKeys[%p]::Create() (%s, %s)", this, origin.get(),
+          topLevelOrigin.get());
+
+  mProxy = CreateCDMProxy();
+
+  // The CDMProxy's initialization is asynchronous. The MediaKeys is
+  // refcounted, and its instance is returned to JS by promise once
+  // it's been initialized. No external refs exist to the MediaKeys while
+  // we're waiting for the promise to be resolved, so we must hold a
+  // reference to the new MediaKeys object until it's been created,
+  // or its creation has failed. Store the id of the promise returned
+  // here, and hold a self-reference until that promise is resolved or
+  // rejected.
+  MOZ_ASSERT(!mCreatePromiseId, "Should only be created once!");
+  mCreatePromiseId = StorePromise(promise);
+  EME_LOG("MediaKeys[%p]::Init() calling AddRef()", this);
+  AddRef();
+  mProxy->Init(mCreatePromiseId, NS_ConvertUTF8toUTF16(origin),
+               NS_ConvertUTF8toUTF16(topLevelOrigin),
+               KeySystemToProxyName(mKeySystem));
+
+  ConnectInnerWindow();
+
+  return promise.forget();
+}
+
+void MediaKeys::OnCDMCreated(PromiseId aId, const uint32_t aPluginId) {
+  EME_LOG("MediaKeys[%p]::OnCDMCreated(aId=%" PRIu32 ", aPluginId=%" PRIu32 ")",
+          this, aId, aPluginId);
+  RefPtr<DetailedPromise> promise(RetrievePromise(aId));
+  if (!promise) {
+    return;
+  }
+  RefPtr<MediaKeys> keys(this);
+
+  promise->MaybeResolve(keys);
+  if (mCreatePromiseId == aId) {
+    EME_LOG("MediaKeys[%p]::OnCDMCreated(aId=%" PRIu32 ", aPluginId=%" PRIu32
+            ") calling Release()",
+            this, aId, aPluginId);
+    Release();
+  }
+
+  MediaKeySystemAccess::NotifyObservers(mParent, mKeySystem,
+                                        MediaKeySystemStatus::Cdm_created);
+}
+
+static bool IsSessionTypeSupported(const MediaKeySessionType aSessionType,
+                                   const MediaKeySystemConfiguration& aConfig) {
+  if (aSessionType == MediaKeySessionType::Temporary) {
+    // Temporary is always supported.
+    return true;
+  }
+  if (!aConfig.mSessionTypes.WasPassed()) {
+    // No other session types supported.
+    return false;
+  }
+  return aConfig.mSessionTypes.Value().Contains(ToString(aSessionType));
+}
+
+already_AddRefed<MediaKeySession> MediaKeys::CreateSession(
+    MediaKeySessionType aSessionType, ErrorResult& aRv) {
+  EME_LOG("MediaKeys[%p]::CreateSession(aSessionType=%" PRIu8 ")", this,
+          static_cast<uint8_t>(aSessionType));
+  if (!IsSessionTypeSupported(aSessionType, mConfig)) {
+    EME_LOG("MediaKeys[%p]::CreateSession() failed, unsupported session type",
+            this);
+    aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
+    return nullptr;
+  }
+
+  if (!mProxy) {
+    NS_WARNING("Tried to use a MediaKeys which lost its CDM");
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return nullptr;
+  }
+
+  EME_LOG("MediaKeys[%p] Creating session", this);
+
+  RefPtr<MediaKeySession> session = new MediaKeySession(
+      GetParentObject(), this, mKeySystem, aSessionType, aRv);
+
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+  DDLINKCHILD("session", session.get());
+
+  // Add session to the set of sessions awaiting their sessionId being ready.
+  EME_LOG("MediaKeys[%p]::CreateSession(aSessionType=%" PRIu8
+          ") putting session with token=%" PRIu32 " into mPendingSessions",
+          this, static_cast<uint8_t>(aSessionType), session->Token());
+  mPendingSessions.InsertOrUpdate(session->Token(), RefPtr{session});
+
+  return session.forget();
+}
+
+void MediaKeys::OnSessionLoaded(PromiseId aId, bool aSuccess) {
+  EME_LOG("MediaKeys[%p]::OnSessionLoaded() resolve promise id=%" PRIu32, this,
+          aId);
+
+  ResolvePromiseWithResult(aId, aSuccess);
+}
+
+void MediaKeys::OnSessionClosed(MediaKeySession* aSession) {
+  nsAutoString id;
+  aSession->GetSessionId(id);
+  mKeySessions.Remove(id);
+}
+
+already_AddRefed<MediaKeySession> MediaKeys::GetSession(
+    const nsAString& aSessionId) {
+  RefPtr<MediaKeySession> session;
+  mKeySessions.Get(aSessionId, getter_AddRefs(session));
+  return session.forget();
+}
+
+already_AddRefed<MediaKeySession> MediaKeys::GetPendingSession(
+    uint32_t aToken) {
+  EME_LOG("MediaKeys[%p]::GetPendingSession(aToken=%" PRIu32 ")", this, aToken);
+  RefPtr<MediaKeySession> session;
+  mPendingSessions.Get(aToken, getter_AddRefs(session));
+  mPendingSessions.Remove(aToken);
+  return session.forget();
+}
+
+bool MediaKeys::IsBoundToMediaElement() const {
+  MOZ_ASSERT(NS_IsMainThread());
+  return mElement != nullptr;
+}
+
+nsresult MediaKeys::Bind(HTMLMediaElement* aElement) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (IsBoundToMediaElement()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mElement = aElement;
+
+  return NS_OK;
+}
+
+void MediaKeys::Unbind() {
+  MOZ_ASSERT(NS_IsMainThread());
+  mElement = nullptr;
+}
+
+void MediaKeys::CheckIsElementCapturePossible() {
+  MOZ_ASSERT(NS_IsMainThread());
+  EME_LOG("MediaKeys[%p]::IsElementCapturePossible()", this);
+  // Note, HTMLMediaElement prevents capture of its content via Capture APIs
+  // on the element if it has a media keys attached (see bug 1071482). So we
+  // don't need to check those cases here (they are covered by tests).
+
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+
+  if (!observerService) {
+    // This can happen if we're in shutdown which means we may be going away
+    // soon anyway, but respond saying capture is possible since we can't
+    // forward the check further.
+    if (mProxy) {
+      mProxy->NotifyOutputProtectionStatus(
+          CDMProxy::OutputProtectionCheckStatus::CheckFailed,
+          CDMProxy::OutputProtectionCaptureStatus::Unused);
+    }
+    return;
+  }
+  if (!mObserverAdded) {
+    nsresult rv =
+        observerService->AddObserver(this, kMediaKeysResponseTopic, false);
+    if (NS_FAILED(rv)) {
+      if (mProxy) {
+        mProxy->NotifyOutputProtectionStatus(
+            CDMProxy::OutputProtectionCheckStatus::CheckFailed,
+            CDMProxy::OutputProtectionCaptureStatus::Unused);
+      }
+      return;
+    }
+    mObserverAdded = true;
+  }
+
+  if (mCaptureCheckRequestJson.IsEmpty()) {
+    // Lazily populate the JSON the first time we need it.
+    JSONStringWriteFunc<nsAutoCString> json;
+    JSONWriter jw{json};
+    jw.Start();
+    jw.StringProperty("status", "is-capture-possible");
+    jw.StringProperty("keySystem", NS_ConvertUTF16toUTF8(mKeySystem));
+    jw.End();
+    mCaptureCheckRequestJson = NS_ConvertUTF8toUTF16(json.StringCRef());
+  }
+
+  MOZ_DIAGNOSTIC_ASSERT(!mCaptureCheckRequestJson.IsEmpty());
+  observerService->NotifyObservers(mParent.get(), kMediaKeysRequestTopic,
+                                   mCaptureCheckRequestJson.get());
+}
+
+void MediaKeys::GetSessionsInfo(nsString& sessionsInfo) {
+  for (const auto& keySession : mKeySessions.Values()) {
+    nsString sessionID;
+    keySession->GetSessionId(sessionID);
+    sessionsInfo.AppendLiteral("(sid=");
+    sessionsInfo.Append(sessionID);
+    MediaKeyStatusMap* keyStatusMap = keySession->KeyStatuses();
+    for (uint32_t i = 0; i < keyStatusMap->GetIterableLength(); i++) {
+      nsString keyID = keyStatusMap->GetKeyIDAsHexString(i);
+      sessionsInfo.AppendLiteral("(kid=");
+      sessionsInfo.Append(keyID);
+      sessionsInfo.AppendLiteral(" status=");
+      sessionsInfo.AppendASCII(
+          MediaKeyStatusValues::GetString(keyStatusMap->GetValueAtIndex(i)));
+      sessionsInfo.AppendLiteral(")");
+    }
+    sessionsInfo.AppendLiteral(")");
+  }
+}
+
+already_AddRefed<Promise> MediaKeys::GetStatusForPolicy(
+    const MediaKeysPolicy& aPolicy, ErrorResult& aRv) {
+  RefPtr<DetailedPromise> promise(
+      MakePromise(aRv, "MediaKeys::GetStatusForPolicy()"_ns));
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // Currently, only widevine CDM supports for this API.
+  if (!IsWidevineKeySystem(mKeySystem)) {
+    EME_LOG(
+        "MediaKeys[%p]::GetStatusForPolicy() HDCP policy check on unsupported "
+        "keysystem ",
+        this);
+    NS_WARNING("Tried to query without a CDM");
+    promise->MaybeRejectWithNotSupportedError(
+        "HDCP policy check on unsupported keysystem");
+    return promise.forget();
+  }
+
+  if (!mProxy) {
+    NS_WARNING("Tried to use a MediaKeys without a CDM");
+    promise->MaybeRejectWithInvalidStateError(
+        "Null CDM in MediaKeys.GetStatusForPolicy()");
+    return promise.forget();
+  }
+
+  EME_LOG("GetStatusForPolicy minHdcpVersion = %s.",
+          NS_ConvertUTF16toUTF8(aPolicy.mMinHdcpVersion).get());
+  mProxy->GetStatusForPolicy(StorePromise(promise), aPolicy.mMinHdcpVersion);
+  return promise.forget();
+}
+
+void MediaKeys::ResolvePromiseWithKeyStatus(PromiseId aId,
+                                            MediaKeyStatus aMediaKeyStatus) {
+  RefPtr<DetailedPromise> promise(RetrievePromise(aId));
+  if (!promise) {
+    return;
+  }
+  RefPtr<MediaKeys> keys(this);
+  EME_LOG(
+      "MediaKeys[%p]::ResolvePromiseWithKeyStatus() resolve promise id=%" PRIu32
+      ", keystatus=%" PRIu8,
+      this, aId, static_cast<uint8_t>(aMediaKeyStatus));
+  promise->MaybeResolve(aMediaKeyStatus);
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/media/eme/MediaKeys.h b/dom/media/eme/MediaKeys.h
new file mode 100644
index 0000000000..5a44b3c227
--- /dev/null
+++ b/dom/media/eme/MediaKeys.h
@@ -0,0 +1,236 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef mozilla_dom_mediakeys_h__
+#define mozilla_dom_mediakeys_h__
+
+#include "DecoderDoctorLogger.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/DetailedPromise.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/WeakPtr.h"
+#include "mozilla/dom/MediaKeyStatusMapBinding.h"  // For MediaKeyStatus
+#include "mozilla/dom/MediaKeySystemAccessBinding.h"
+#include "mozilla/dom/MediaKeysBinding.h"
+#include "mozilla/dom/Promise.h"
+#include "nsCOMPtr.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsIObserver.h"
+#include "nsRefPtrHashtable.h"
+#include "nsTHashMap.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+
+class CDMProxy;
+
+namespace dom {
+class MediaKeys;
+}  // namespace dom
+DDLoggedTypeName(dom::MediaKeys);
+
+namespace dom {
+
+class ArrayBufferViewOrArrayBuffer;
+class MediaKeySession;
+struct MediaKeysPolicy;
+class HTMLMediaElement;
+
+typedef nsRefPtrHashtable<nsStringHashKey, MediaKeySession> KeySessionHashMap;
+typedef nsRefPtrHashtable<nsUint32HashKey, dom::DetailedPromise> PromiseHashMap;
+typedef nsRefPtrHashtable<nsUint32HashKey, MediaKeySession>
+    PendingKeySessionsHashMap;
+typedef nsTHashMap<nsUint32HashKey, uint32_t> PendingPromiseIdTokenHashMap;
+typedef uint32_t PromiseId;
+
+// This class is used on the main thread only.
+// Note: its addref/release is not (and can't be) thread safe!
+class MediaKeys final : public nsIObserver,
+                        public nsWrapperCache,
+                        public SupportsWeakPtr,
+                        public DecoderDoctorLifeLogger<MediaKeys> {
+  ~MediaKeys();
+
+ public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(MediaKeys)
+
+  NS_DECL_NSIOBSERVER
+
+  MediaKeys(nsPIDOMWindowInner* aParentWindow, const nsAString& aKeySystem,
+            const MediaKeySystemConfiguration& aConfig);
+
+  already_AddRefed<DetailedPromise> Init(ErrorResult& aRv);
+
+  nsPIDOMWindowInner* GetParentObject() const;
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+
+  nsresult Bind(HTMLMediaElement* aElement);
+  void Unbind();
+
+  // Checks if there's any activity happening that could capture the media
+  // the keys are associated with and then expose that media outside of the
+  // origin it is in.
+  //
+  // This method does not return the results of the check, but the MediaKeys
+  // will notify mProxy of the results using `NotifyOutputProtectionStatus`.
+  void CheckIsElementCapturePossible();
+
+  // Javascript: readonly attribute DOMString keySystem;
+  void GetKeySystem(nsString& retval) const;
+
+  // JavaScript: MediaKeys.createSession()
+  already_AddRefed<MediaKeySession> CreateSession(
+      MediaKeySessionType aSessionType, ErrorResult& aRv);
+
+  // JavaScript: MediaKeys.SetServerCertificate()
+  already_AddRefed<DetailedPromise> SetServerCertificate(
+      const ArrayBufferViewOrArrayBuffer& aServerCertificate, ErrorResult& aRv);
+
+  already_AddRefed<MediaKeySession> GetSession(const nsAString& aSessionId);
+
+  // Removes and returns MediaKeySession from the set of sessions awaiting
+  // their sessionId to be assigned.
+  already_AddRefed<MediaKeySession> GetPendingSession(uint32_t aToken);
+
+  // Called once a Init() operation succeeds.
+  void OnCDMCreated(PromiseId aId, const uint32_t aPluginId);
+
+  // Called once the CDM generates a sessionId while servicing a
+  // MediaKeySession.generateRequest() or MediaKeySession.load() call,
+  // once the sessionId of a MediaKeySession is known.
+  void OnSessionIdReady(MediaKeySession* aSession);
+
+  // Called once a LoadSession succeeds.
+  void OnSessionLoaded(PromiseId aId, bool aSuccess);
+
+  // Called once a session has closed.
+  void OnSessionClosed(MediaKeySession* aSession);
+
+  CDMProxy* GetCDMProxy() { return mProxy; }
+
+  // Makes a new promise, or nullptr on failure.
+  already_AddRefed<DetailedPromise> MakePromise(ErrorResult& aRv,
+                                                const nsACString& aName);
+  // Stores promise in mPromises, returning an ID that can be used to retrieve
+  // it later. The ID is passed to the CDM, so that it can signal specific
+  // promises to be resolved.
+  PromiseId StorePromise(DetailedPromise* aPromise);
+
+  // Stores a map from promise id to pending session token. Using this
+  // mapping, when a promise is rejected via its ID, we can check if the
+  // promise corresponds to a pending session and retrieve that session
+  // via the mapped-to token, and remove the pending session from the
+  // list of sessions awaiting a session id.
+  void ConnectPendingPromiseIdWithToken(PromiseId aId, uint32_t aToken);
+
+  // Reject promise with the given exception.
+  void RejectPromise(PromiseId aId, ErrorResult&& aException,
+                     const nsCString& aReason);
+  // Resolves promise with "undefined".
+  void ResolvePromise(PromiseId aId);
+
+  void Shutdown();
+
+  // Called by CDMProxy when CDM crashes or shuts down. It is different from
+  // Shutdown which is called from the script/dom side.
+  void Terminated();
+
+  // Returns true if this MediaKeys has been bound to a media element.
+  bool IsBoundToMediaElement() const;
+
+  // Indicates to a MediaKeys instance that the inner window parent of that
+  // instance is being destroyed, this should prompt the keys to shutdown.
+  void OnInnerWindowDestroy();
+
+  void GetSessionsInfo(nsString& sessionsInfo);
+
+  // JavaScript: MediaKeys.GetStatusForPolicy()
+  already_AddRefed<Promise> GetStatusForPolicy(const MediaKeysPolicy& aPolicy,
+                                               ErrorResult& aR);
+  // Called by CDMProxy when CDM successfully GetStatusForPolicy.
+  void ResolvePromiseWithKeyStatus(PromiseId aId,
+                                   dom::MediaKeyStatus aMediaKeyStatus);
+
+  template <typename T>
+  void ResolvePromiseWithResult(PromiseId aId, const T& aResult) {
+    RefPtr<DetailedPromise> promise(RetrievePromise(aId));
+    if (!promise) {
+      return;
+    }
+    promise->MaybeResolve(aResult);
+  }
+
+  // The topic used for requests related to mediakeys -- observe this to be
+  // notified of such requests.
+  constexpr static const char* kMediaKeysRequestTopic = "mediakeys-request";
+
+ private:
+  // Instantiate CDMProxy instance.
+  // It could be MediaDrmCDMProxy (Widevine on Fennec) or ChromiumCDMProxy (the
+  // rest).
+  already_AddRefed<CDMProxy> CreateCDMProxy();
+
+  // Removes promise from mPromises, and returns it.
+  already_AddRefed<DetailedPromise> RetrievePromise(PromiseId aId);
+
+  // Helpers to connect and disconnect to the parent inner window. An inner
+  // window should track (via weak ptr) MediaKeys created within it so we can
+  // ensure MediaKeys are shutdown if that window is destroyed.
+  void ConnectInnerWindow();
+  void DisconnectInnerWindow();
+
+  // Owning ref to proxy. The proxy has a weak reference back to the MediaKeys,
+  // and the MediaKeys destructor clears the proxy's reference to the MediaKeys.
+  RefPtr<CDMProxy> mProxy;
+
+  // The HTMLMediaElement the MediaKeys are associated with. Note that a
+  // MediaKeys instance may not be associated with any HTMLMediaElement so
+  // this can be null (we also cannot rely on a media element to drive shutdown
+  // for this reason).
+  RefPtr<HTMLMediaElement> mElement;
+
+  // The  inner window associated with an instance of MediaKeys. We will
+  // shutdown the media keys when this Window is destroyed. We do this from the
+  // window rather than a document to address the case where media keys can be
+  // created in an about:blank document that then performs an async load -- this
+  // recreates the document, but the inner window is preserved in such a case.
+  // See https://bugzilla.mozilla.org/show_bug.cgi?id=1675360 for more info.
+  nsCOMPtr<nsPIDOMWindowInner> mParent;
+  const nsString mKeySystem;
+  KeySessionHashMap mKeySessions;
+  PromiseHashMap mPromises;
+  PendingKeySessionsHashMap mPendingSessions;
+  PromiseId mCreatePromiseId;
+
+  // The principal of the relevant settings object.
+  RefPtr<nsIPrincipal> mPrincipal;
+  // The principal of the top level page. This can differ from mPrincipal if
+  // we're in an iframe.
+  RefPtr<nsIPrincipal> mTopLevelPrincipal;
+
+  const MediaKeySystemConfiguration mConfig;
+
+  PendingPromiseIdTokenHashMap mPromiseIdToken;
+
+  // The topic a MediaKeys instance will observe to receive updates from
+  // EncryptedMediaChild.
+  constexpr static const char* kMediaKeysResponseTopic = "mediakeys-response";
+  // Tracks if we've added an observer for responses from the associated
+  // EncryptedMediaChild. When true an observer is already in place, otherwise
+  // the observer has not yet been added.
+  bool mObserverAdded = false;
+  // Stores the json request we will send to EncryptedMediaChild when querying
+  // output protection. Lazily populated upon first use.
+  nsString mCaptureCheckRequestJson;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_mediakeys_h__
diff --git a/dom/media/eme/mediadrm/MediaDrmCDMCallbackProxy.cpp b/dom/media/eme/mediadrm/MediaDrmCDMCallbackProxy.cpp
new file mode 100644
index 0000000000..e5431f50fd
--- /dev/null
+++ b/dom/media/eme/mediadrm/MediaDrmCDMCallbackProxy.cpp
@@ -0,0 +1,115 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 "MediaDrmCDMCallbackProxy.h"
+#include "MediaDrmCDMProxy.h"
+#include "nsString.h"
+#include "mozilla/dom/MediaKeys.h"
+#include "mozilla/dom/MediaKeySession.h"
+#include "nsContentCID.h"
+#include "nsServiceManagerUtils.h"
+#include "MainThreadUtils.h"
+#include "mozilla/EMEUtils.h"
+
+namespace mozilla {
+
+MediaDrmCDMCallbackProxy::MediaDrmCDMCallbackProxy(MediaDrmCDMProxy* aProxy)
+    : mProxy(aProxy) {}
+
+MediaDrmCDMCallbackProxy::~MediaDrmCDMCallbackProxy() = default;
+
+void MediaDrmCDMCallbackProxy::SetSessionId(uint32_t aToken,
+                                            const nsCString& aSessionId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mProxy->OnSetSessionId(aToken, NS_ConvertUTF8toUTF16(aSessionId));
+}
+
+void MediaDrmCDMCallbackProxy::ResolveLoadSessionPromise(uint32_t aPromiseId,
+                                                         bool aSuccess) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mProxy->OnResolveLoadSessionPromise(aPromiseId, aSuccess);
+}
+
+void MediaDrmCDMCallbackProxy::ResolvePromise(uint32_t aPromiseId) {
+  // Note: CDMProxy proxies this from non-main threads to main thread.
+  mProxy->ResolvePromise(aPromiseId);
+}
+
+void MediaDrmCDMCallbackProxy::RejectPromise(uint32_t aPromiseId,
+                                             ErrorResult&& aException,
+                                             const nsCString& aMessage) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mProxy->OnRejectPromise(aPromiseId, std::move(aException), aMessage);
+}
+
+void MediaDrmCDMCallbackProxy::SessionMessage(
+    const nsCString& aSessionId, dom::MediaKeyMessageType aMessageType,
+    const nsTArray<uint8_t>& aMessage) {
+  MOZ_ASSERT(NS_IsMainThread());
+  // For removing constness
+  nsTArray<uint8_t> message(aMessage.Clone());
+  mProxy->OnSessionMessage(NS_ConvertUTF8toUTF16(aSessionId), aMessageType,
+                           message);
+}
+
+void MediaDrmCDMCallbackProxy::ExpirationChange(const nsCString& aSessionId,
+                                                UnixTime aExpiryTime) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mProxy->OnExpirationChange(NS_ConvertUTF8toUTF16(aSessionId), aExpiryTime);
+}
+
+void MediaDrmCDMCallbackProxy::SessionClosed(const nsCString& aSessionId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  bool keyStatusesChange = false;
+  {
+    auto caps = mProxy->Capabilites().Lock();
+    keyStatusesChange =
+        caps->RemoveKeysForSession(NS_ConvertUTF8toUTF16(aSessionId));
+  }
+  if (keyStatusesChange) {
+    mProxy->OnKeyStatusesChange(NS_ConvertUTF8toUTF16(aSessionId));
+  }
+  mProxy->OnSessionClosed(NS_ConvertUTF8toUTF16(aSessionId));
+}
+
+void MediaDrmCDMCallbackProxy::SessionError(const nsCString& aSessionId,
+                                            nsresult aException,
+                                            uint32_t aSystemCode,
+                                            const nsCString& aMessage) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mProxy->OnSessionError(NS_ConvertUTF8toUTF16(aSessionId), aException,
+                         aSystemCode, NS_ConvertUTF8toUTF16(aMessage));
+}
+
+void MediaDrmCDMCallbackProxy::BatchedKeyStatusChanged(
+    const nsCString& aSessionId, const nsTArray<CDMKeyInfo>& aKeyInfos) {
+  MOZ_ASSERT(NS_IsMainThread());
+  BatchedKeyStatusChangedInternal(aSessionId, aKeyInfos);
+}
+
+void MediaDrmCDMCallbackProxy::BatchedKeyStatusChangedInternal(
+    const nsCString& aSessionId, const nsTArray<CDMKeyInfo>& aKeyInfos) {
+  bool keyStatusesChange = false;
+  {
+    auto caps = mProxy->Capabilites().Lock();
+    for (size_t i = 0; i < aKeyInfos.Length(); i++) {
+      keyStatusesChange |= caps->SetKeyStatus(aKeyInfos[i].mKeyId,
+                                              NS_ConvertUTF8toUTF16(aSessionId),
+                                              aKeyInfos[i].mStatus);
+    }
+  }
+  if (keyStatusesChange) {
+    mProxy->OnKeyStatusesChange(NS_ConvertUTF8toUTF16(aSessionId));
+  }
+}
+
+void MediaDrmCDMCallbackProxy::Decrypted(
+    uint32_t aId, DecryptStatus aResult,
+    const nsTArray<uint8_t>& aDecryptedData) {
+  MOZ_ASSERT_UNREACHABLE("Fennec could not handle decrypted event");
+}
+
+}  // namespace mozilla
diff --git a/dom/media/eme/mediadrm/MediaDrmCDMCallbackProxy.h b/dom/media/eme/mediadrm/MediaDrmCDMCallbackProxy.h
new file mode 100644
index 0000000000..e963e21e11
--- /dev/null
+++ b/dom/media/eme/mediadrm/MediaDrmCDMCallbackProxy.h
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef MediaDrmCDMCallbackProxy_h_
+#define MediaDrmCDMCallbackProxy_h_
+
+#include "mozilla/CDMProxy.h"
+#include "mozilla/DecryptorProxyCallback.h"
+
+namespace mozilla {
+class CDMProxy;
+class ErrorResult;
+class MediaDrmCDMProxy;
+
+// Proxies call backs from the MediaDrmProxy -> MediaDrmProxySupport back to the
+// MediaKeys object on the main thread. We used annotation calledFrom = "gecko"
+// to ensure running on main thread.
+class MediaDrmCDMCallbackProxy final : public DecryptorProxyCallback {
+ public:
+  void SetSessionId(uint32_t aCreateSessionToken,
+                    const nsCString& aSessionId) override;
+
+  void ResolveLoadSessionPromise(uint32_t aPromiseId, bool aSuccess) override;
+
+  void ResolvePromise(uint32_t aPromiseId) override;
+
+  void RejectPromise(uint32_t aPromiseId, ErrorResult&& aException,
+                     const nsCString& aSessionId) override;
+
+  void SessionMessage(const nsCString& aSessionId,
+                      dom::MediaKeyMessageType aMessageType,
+                      const nsTArray<uint8_t>& aMessage) override;
+
+  void ExpirationChange(const nsCString& aSessionId,
+                        UnixTime aExpiryTime) override;
+
+  void SessionClosed(const nsCString& aSessionId) override;
+
+  void SessionError(const nsCString& aSessionId, nsresult aException,
+                    uint32_t aSystemCode, const nsCString& aMessage) override;
+
+  void Decrypted(uint32_t aId, DecryptStatus aResult,
+                 const nsTArray<uint8_t>& aDecryptedData) override;
+
+  void BatchedKeyStatusChanged(const nsCString& aSessionId,
+                               const nsTArray<CDMKeyInfo>& aKeyInfos) override;
+
+  ~MediaDrmCDMCallbackProxy();
+
+ private:
+  friend class MediaDrmCDMProxy;
+  explicit MediaDrmCDMCallbackProxy(MediaDrmCDMProxy* aProxy);
+
+  void BatchedKeyStatusChangedInternal(const nsCString& aSessionId,
+                                       const nsTArray<CDMKeyInfo>& aKeyInfos);
+  const RefPtr<MediaDrmCDMProxy> mProxy;
+};
+
+}  // namespace mozilla
+#endif
diff --git a/dom/media/eme/mediadrm/MediaDrmCDMProxy.cpp b/dom/media/eme/mediadrm/MediaDrmCDMProxy.cpp
new file mode 100644
index 0000000000..07b7bfe3a0
--- /dev/null
+++ b/dom/media/eme/mediadrm/MediaDrmCDMProxy.cpp
@@ -0,0 +1,453 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/MediaKeySession.h"
+#include "mozilla/MediaDrmCDMProxy.h"
+#include "MediaDrmCDMCallbackProxy.h"
+
+namespace mozilla {
+
+MediaDrmSessionType ToMediaDrmSessionType(
+    dom::MediaKeySessionType aSessionType) {
+  switch (aSessionType) {
+    case dom::MediaKeySessionType::Temporary:
+      return kKeyStreaming;
+    case dom::MediaKeySessionType::Persistent_license:
+      return kKeyOffline;
+    default:
+      return kKeyStreaming;
+  };
+}
+
+MediaDrmCDMProxy::MediaDrmCDMProxy(dom::MediaKeys* aKeys,
+                                   const nsAString& aKeySystem,
+                                   bool aDistinctiveIdentifierRequired,
+                                   bool aPersistentStateRequired)
+    : CDMProxy(aKeys, aKeySystem, aDistinctiveIdentifierRequired,
+               aPersistentStateRequired),
+      mCDM(nullptr),
+      mShutdownCalled(false) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_COUNT_CTOR(MediaDrmCDMProxy);
+}
+
+MediaDrmCDMProxy::~MediaDrmCDMProxy() { MOZ_COUNT_DTOR(MediaDrmCDMProxy); }
+
+void MediaDrmCDMProxy::Init(PromiseId aPromiseId, const nsAString& aOrigin,
+                            const nsAString& aTopLevelOrigin,
+                            const nsAString& aName) {
+  MOZ_ASSERT(NS_IsMainThread());
+  NS_ENSURE_TRUE_VOID(!mKeys.IsNull());
+
+  EME_LOG("MediaDrmCDMProxy::Init (%s, %s) %s",
+          NS_ConvertUTF16toUTF8(aOrigin).get(),
+          NS_ConvertUTF16toUTF8(aTopLevelOrigin).get(),
+          NS_ConvertUTF16toUTF8(aName).get());
+
+  // Create a thread to work with cdm.
+  if (!mOwnerThread) {
+    nsresult rv =
+        NS_NewNamedThread("MDCDMThread", getter_AddRefs(mOwnerThread));
+    if (NS_FAILED(rv)) {
+      RejectPromiseWithStateError(
+          aPromiseId, nsLiteralCString(
+                          "Couldn't create CDM thread MediaDrmCDMProxy::Init"));
+      return;
+    }
+  }
+
+  mCDM = mozilla::MakeUnique<MediaDrmProxySupport>(mKeySystem);
+  nsCOMPtr<nsIRunnable> task(
+      NewRunnableMethod<uint32_t>("MediaDrmCDMProxy::md_Init", this,
+                                  &MediaDrmCDMProxy::md_Init, aPromiseId));
+  mOwnerThread->Dispatch(task, NS_DISPATCH_NORMAL);
+}
+
+void MediaDrmCDMProxy::CreateSession(uint32_t aCreateSessionToken,
+                                     MediaKeySessionType aSessionType,
+                                     PromiseId aPromiseId,
+                                     const nsAString& aInitDataType,
+                                     nsTArray<uint8_t>& aInitData) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mOwnerThread);
+
+  UniquePtr<CreateSessionData> data(new CreateSessionData());
+  data->mSessionType = aSessionType;
+  data->mCreateSessionToken = aCreateSessionToken;
+  data->mPromiseId = aPromiseId;
+  data->mInitDataType = NS_ConvertUTF16toUTF8(aInitDataType);
+  data->mInitData = std::move(aInitData);
+
+  nsCOMPtr<nsIRunnable> task(NewRunnableMethod<UniquePtr<CreateSessionData>&&>(
+      "MediaDrmCDMProxy::md_CreateSession", this,
+      &MediaDrmCDMProxy::md_CreateSession, std::move(data)));
+  mOwnerThread->Dispatch(task, NS_DISPATCH_NORMAL);
+}
+
+void MediaDrmCDMProxy::LoadSession(PromiseId aPromiseId,
+                                   dom::MediaKeySessionType aSessionType,
+                                   const nsAString& aSessionId) {
+  // TODO: Implement LoadSession.
+  RejectPromiseWithStateError(
+      aPromiseId, "Currently Fennec does not support LoadSession"_ns);
+}
+
+void MediaDrmCDMProxy::SetServerCertificate(PromiseId aPromiseId,
+                                            nsTArray<uint8_t>& aCert) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mOwnerThread);
+
+  mOwnerThread->Dispatch(NewRunnableMethod<PromiseId, const nsTArray<uint8_t>>(
+                             "MediaDrmCDMProxy::md_SetServerCertificate", this,
+                             &MediaDrmCDMProxy::md_SetServerCertificate,
+                             aPromiseId, std::move(aCert)),
+                         NS_DISPATCH_NORMAL);
+}
+
+void MediaDrmCDMProxy::UpdateSession(const nsAString& aSessionId,
+                                     PromiseId aPromiseId,
+                                     nsTArray<uint8_t>& aResponse) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mOwnerThread);
+  NS_ENSURE_TRUE_VOID(!mKeys.IsNull());
+
+  UniquePtr<UpdateSessionData> data(new UpdateSessionData());
+  data->mPromiseId = aPromiseId;
+  data->mSessionId = NS_ConvertUTF16toUTF8(aSessionId);
+  data->mResponse = std::move(aResponse);
+
+  nsCOMPtr<nsIRunnable> task(NewRunnableMethod<UniquePtr<UpdateSessionData>&&>(
+      "MediaDrmCDMProxy::md_UpdateSession", this,
+      &MediaDrmCDMProxy::md_UpdateSession, std::move(data)));
+  mOwnerThread->Dispatch(task, NS_DISPATCH_NORMAL);
+}
+
+void MediaDrmCDMProxy::CloseSession(const nsAString& aSessionId,
+                                    PromiseId aPromiseId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mOwnerThread);
+  NS_ENSURE_TRUE_VOID(!mKeys.IsNull());
+
+  UniquePtr<SessionOpData> data(new SessionOpData());
+  data->mPromiseId = aPromiseId;
+  data->mSessionId = NS_ConvertUTF16toUTF8(aSessionId);
+
+  nsCOMPtr<nsIRunnable> task(NewRunnableMethod<UniquePtr<SessionOpData>&&>(
+      "MediaDrmCDMProxy::md_CloseSession", this,
+      &MediaDrmCDMProxy::md_CloseSession, std::move(data)));
+  mOwnerThread->Dispatch(task, NS_DISPATCH_NORMAL);
+}
+
+void MediaDrmCDMProxy::RemoveSession(const nsAString& aSessionId,
+                                     PromiseId aPromiseId) {
+  // TODO: Implement RemoveSession.
+  RejectPromiseWithStateError(
+      aPromiseId, "Currently Fennec does not support RemoveSession"_ns);
+}
+
+void MediaDrmCDMProxy::QueryOutputProtectionStatus() {
+  // TODO(bryce): determine if this is needed for Android and implement as
+  // needed. See also `NotifyOutputProtectionStatus`.
+}
+
+void MediaDrmCDMProxy::NotifyOutputProtectionStatus(
+    OutputProtectionCheckStatus aCheckStatus,
+    OutputProtectionCaptureStatus aCaptureStatus) {
+  // TODO(bryce): determine if this is needed for Android and implement as
+  // needed. See also `QueryOutputProtectionStatus`.
+}
+
+void MediaDrmCDMProxy::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mOwnerThread);
+  nsCOMPtr<nsIRunnable> task(NewRunnableMethod(
+      "MediaDrmCDMProxy::md_Shutdown", this, &MediaDrmCDMProxy::md_Shutdown));
+
+  mOwnerThread->Dispatch(task, NS_DISPATCH_NORMAL);
+  mOwnerThread->Shutdown();
+  mOwnerThread = nullptr;
+  mKeys.Clear();
+}
+
+void MediaDrmCDMProxy::Terminated() {
+  // TODO: Implement Terminated.
+  // Should find a way to handle the case when remote side MediaDrm crashed.
+}
+
+void MediaDrmCDMProxy::OnSetSessionId(uint32_t aCreateSessionToken,
+                                      const nsAString& aSessionId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mKeys.IsNull()) {
+    return;
+  }
+
+  RefPtr<dom::MediaKeySession> session(
+      mKeys->GetPendingSession(aCreateSessionToken));
+  if (session) {
+    session->SetSessionId(aSessionId);
+  }
+}
+
+void MediaDrmCDMProxy::OnResolveLoadSessionPromise(uint32_t aPromiseId,
+                                                   bool aSuccess) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mKeys.IsNull()) {
+    return;
+  }
+  mKeys->OnSessionLoaded(aPromiseId, aSuccess);
+}
+
+void MediaDrmCDMProxy::OnSessionMessage(const nsAString& aSessionId,
+                                        dom::MediaKeyMessageType aMessageType,
+                                        const nsTArray<uint8_t>& aMessage) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mKeys.IsNull()) {
+    return;
+  }
+  RefPtr<dom::MediaKeySession> session(mKeys->GetSession(aSessionId));
+  if (session) {
+    session->DispatchKeyMessage(aMessageType, aMessage);
+  }
+}
+
+void MediaDrmCDMProxy::OnExpirationChange(const nsAString& aSessionId,
+                                          UnixTime aExpiryTime) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mKeys.IsNull()) {
+    return;
+  }
+  RefPtr<dom::MediaKeySession> session(mKeys->GetSession(aSessionId));
+  if (session) {
+    session->SetExpiration(static_cast<double>(aExpiryTime));
+  }
+}
+
+void MediaDrmCDMProxy::OnSessionClosed(const nsAString& aSessionId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mKeys.IsNull()) {
+    return;
+  }
+  RefPtr<dom::MediaKeySession> session(mKeys->GetSession(aSessionId));
+  if (session) {
+    session->OnClosed();
+  }
+}
+
+void MediaDrmCDMProxy::OnSessionError(const nsAString& aSessionId,
+                                      nsresult aException, uint32_t aSystemCode,
+                                      const nsAString& aMsg) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mKeys.IsNull()) {
+    return;
+  }
+  RefPtr<dom::MediaKeySession> session(mKeys->GetSession(aSessionId));
+  if (session) {
+    session->DispatchKeyError(aSystemCode);
+  }
+}
+
+void MediaDrmCDMProxy::OnRejectPromise(uint32_t aPromiseId,
+                                       ErrorResult&& aException,
+                                       const nsCString& aMsg) {
+  MOZ_ASSERT(NS_IsMainThread());
+  RejectPromise(aPromiseId, std::move(aException), aMsg);
+}
+
+RefPtr<DecryptPromise> MediaDrmCDMProxy::Decrypt(MediaRawData* aSample) {
+  MOZ_ASSERT_UNREACHABLE("Fennec could not handle decrypting individually");
+  return nullptr;
+}
+
+void MediaDrmCDMProxy::OnDecrypted(uint32_t aId, DecryptStatus aResult,
+                                   const nsTArray<uint8_t>& aDecryptedData) {
+  MOZ_ASSERT_UNREACHABLE("Fennec could not handle decrypted event");
+}
+
+void MediaDrmCDMProxy::RejectPromise(PromiseId aId, ErrorResult&& aException,
+                                     const nsCString& aReason) {
+  if (NS_IsMainThread()) {
+    if (!mKeys.IsNull()) {
+      mKeys->RejectPromise(aId, std::move(aException), aReason);
+    }
+  } else {
+    nsCOMPtr<nsIRunnable> task(
+        new RejectPromiseTask(this, aId, std::move(aException), aReason));
+    mMainThread->Dispatch(task.forget(), NS_DISPATCH_NORMAL);
+  }
+}
+
+void MediaDrmCDMProxy::RejectPromiseWithStateError(PromiseId aId,
+                                                   const nsCString& aReason) {
+  ErrorResult rv;
+  rv.ThrowInvalidStateError(aReason);
+  RejectPromise(aId, std::move(rv), aReason);
+}
+
+void MediaDrmCDMProxy::ResolvePromise(PromiseId aId) {
+  if (NS_IsMainThread()) {
+    if (!mKeys.IsNull()) {
+      mKeys->ResolvePromise(aId);
+    } else {
+      NS_WARNING("MediaDrmCDMProxy unable to resolve promise!");
+    }
+  } else {
+    nsCOMPtr<nsIRunnable> task;
+    task =
+        NewRunnableMethod<PromiseId>("MediaDrmCDMProxy::ResolvePromise", this,
+                                     &MediaDrmCDMProxy::ResolvePromise, aId);
+    mMainThread->Dispatch(task.forget(), NS_DISPATCH_NORMAL);
+  }
+}
+
+template <typename T>
+void MediaDrmCDMProxy::ResolvePromiseWithResult(PromiseId aId,
+                                                const T& aResult) {
+  if (NS_IsMainThread()) {
+    if (!mKeys.IsNull()) {
+      mKeys->ResolvePromiseWithResult(aId, aResult);
+    } else {
+      NS_WARNING("MediaDrmCDMProxy unable to resolve promise!");
+    }
+    return;
+  }
+
+  nsCOMPtr<nsIRunnable> task;
+  task = NewRunnableMethod<PromiseId, T>(
+      "MediaDrmCDMProxy::ResolvePromiseWithResult", this,
+      &MediaDrmCDMProxy::ResolvePromiseWithResult<T>, aId, aResult);
+  mMainThread->Dispatch(task.forget(), NS_DISPATCH_NORMAL);
+}
+
+void MediaDrmCDMProxy::OnKeyStatusesChange(const nsAString& aSessionId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mKeys.IsNull()) {
+    return;
+  }
+  RefPtr<dom::MediaKeySession> session(mKeys->GetSession(aSessionId));
+  if (session) {
+    session->DispatchKeyStatusesChange();
+  }
+}
+
+void MediaDrmCDMProxy::GetStatusForPolicy(PromiseId aPromiseId,
+                                          const nsAString& aMinHdcpVersion) {
+  // TODO: Implement GetStatusForPolicy.
+  constexpr auto err =
+      "Currently Fennec does not support GetStatusForPolicy"_ns;
+
+  ErrorResult rv;
+  rv.ThrowNotSupportedError(err);
+  RejectPromise(aPromiseId, std::move(rv), err);
+}
+
+#ifdef DEBUG
+bool MediaDrmCDMProxy::IsOnOwnerThread() {
+  return NS_GetCurrentThread() == mOwnerThread;
+}
+#endif
+
+const nsString& MediaDrmCDMProxy::GetMediaDrmStubId() const {
+  MOZ_ASSERT(mCDM);
+  return mCDM->GetMediaDrmStubId();
+}
+
+void MediaDrmCDMProxy::OnCDMCreated(uint32_t aPromiseId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mKeys.IsNull()) {
+    return;
+  }
+
+  if (mCDM) {
+    mKeys->OnCDMCreated(aPromiseId, 0);
+    return;
+  }
+
+  // No CDM? Just reject the promise.
+  constexpr auto err = "Null CDM in OnCDMCreated()"_ns;
+  ErrorResult rv;
+  rv.ThrowInvalidStateError(err);
+  mKeys->RejectPromise(aPromiseId, std::move(rv), err);
+}
+
+void MediaDrmCDMProxy::md_Init(uint32_t aPromiseId) {
+  MOZ_ASSERT(IsOnOwnerThread());
+  MOZ_ASSERT(mCDM);
+
+  UniquePtr<MediaDrmCDMCallbackProxy> callback(
+      new MediaDrmCDMCallbackProxy(this));
+  mCDM->Init(std::move(callback));
+  nsCOMPtr<nsIRunnable> task(
+      NewRunnableMethod<uint32_t>("MediaDrmCDMProxy::OnCDMCreated", this,
+                                  &MediaDrmCDMProxy::OnCDMCreated, aPromiseId));
+  mMainThread->Dispatch(task.forget(), NS_DISPATCH_NORMAL);
+}
+
+void MediaDrmCDMProxy::md_CreateSession(UniquePtr<CreateSessionData>&& aData) {
+  MOZ_ASSERT(IsOnOwnerThread());
+
+  if (!mCDM) {
+    RejectPromiseWithStateError(aData->mPromiseId,
+                                "Null CDM in md_CreateSession"_ns);
+    return;
+  }
+
+  mCDM->CreateSession(aData->mCreateSessionToken, aData->mPromiseId,
+                      aData->mInitDataType, aData->mInitData,
+                      ToMediaDrmSessionType(aData->mSessionType));
+}
+
+void MediaDrmCDMProxy::md_SetServerCertificate(PromiseId aPromiseId,
+                                               const nsTArray<uint8_t>& aCert) {
+  MOZ_ASSERT(IsOnOwnerThread());
+
+  if (!mCDM) {
+    RejectPromiseWithStateError(aPromiseId,
+                                "Null CDM in md_SetServerCertificate"_ns);
+    return;
+  }
+
+  if (mCDM->SetServerCertificate(aCert)) {
+    ResolvePromiseWithResult(aPromiseId, true);
+  } else {
+    RejectPromiseWithStateError(
+        aPromiseId, "MediaDrmCDMProxy unable to set server certificate"_ns);
+  }
+}
+
+void MediaDrmCDMProxy::md_UpdateSession(UniquePtr<UpdateSessionData>&& aData) {
+  MOZ_ASSERT(IsOnOwnerThread());
+
+  if (!mCDM) {
+    RejectPromiseWithStateError(aData->mPromiseId,
+                                "Null CDM in md_UpdateSession"_ns);
+    return;
+  }
+  mCDM->UpdateSession(aData->mPromiseId, aData->mSessionId, aData->mResponse);
+}
+
+void MediaDrmCDMProxy::md_CloseSession(UniquePtr<SessionOpData>&& aData) {
+  MOZ_ASSERT(IsOnOwnerThread());
+
+  if (!mCDM) {
+    RejectPromiseWithStateError(aData->mPromiseId,
+                                "Null CDM in md_CloseSession"_ns);
+    return;
+  }
+  mCDM->CloseSession(aData->mPromiseId, aData->mSessionId);
+}
+
+void MediaDrmCDMProxy::md_Shutdown() {
+  MOZ_ASSERT(IsOnOwnerThread());
+  MOZ_ASSERT(mCDM);
+  if (mShutdownCalled) {
+    return;
+  }
+  mShutdownCalled = true;
+  mCDM->Shutdown();
+  mCDM = nullptr;
+}
+
+}  // namespace mozilla
diff --git a/dom/media/eme/mediadrm/MediaDrmCDMProxy.h b/dom/media/eme/mediadrm/MediaDrmCDMProxy.h
new file mode 100644
index 0000000000..60a541ece9
--- /dev/null
+++ b/dom/media/eme/mediadrm/MediaDrmCDMProxy.h
@@ -0,0 +1,186 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef MediaDrmCDMProxy_h_
+#define MediaDrmCDMProxy_h_
+
+#include <jni.h>
+#include "mozilla/jni/Types.h"
+#include "mozilla/CDMProxy.h"
+#include "mozilla/CDMCaps.h"
+#include "mozilla/dom/MediaKeys.h"
+#include "mozilla/dom/MediaKeySession.h"
+#include "mozilla/MediaDrmProxySupport.h"
+#include "mozilla/UniquePtr.h"
+
+#include "MediaCodec.h"
+#include "nsString.h"
+
+namespace mozilla {
+
+class MediaDrmCDMCallbackProxy;
+class MediaDrmCDMProxy final : public CDMProxy {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaDrmCDMProxy, override)
+
+  MediaDrmCDMProxy(dom::MediaKeys* aKeys, const nsAString& aKeySystem,
+                   bool aDistinctiveIdentifierRequired,
+                   bool aPersistentStateRequired);
+
+  void Init(PromiseId aPromiseId, const nsAString& aOrigin,
+            const nsAString& aTopLevelOrigin,
+            const nsAString& aGMPName) override;
+
+  void CreateSession(uint32_t aCreateSessionToken,
+                     MediaKeySessionType aSessionType, PromiseId aPromiseId,
+                     const nsAString& aInitDataType,
+                     nsTArray<uint8_t>& aInitData) override;
+
+  void LoadSession(PromiseId aPromiseId, dom::MediaKeySessionType aSessionType,
+                   const nsAString& aSessionId) override;
+
+  void SetServerCertificate(PromiseId aPromiseId,
+                            nsTArray<uint8_t>& aCert) override;
+
+  void UpdateSession(const nsAString& aSessionId, PromiseId aPromiseId,
+                     nsTArray<uint8_t>& aResponse) override;
+
+  void CloseSession(const nsAString& aSessionId, PromiseId aPromiseId) override;
+
+  void RemoveSession(const nsAString& aSessionId,
+                     PromiseId aPromiseId) override;
+
+  void QueryOutputProtectionStatus() override;
+
+  void NotifyOutputProtectionStatus(
+      OutputProtectionCheckStatus aCheckStatus,
+      OutputProtectionCaptureStatus aCaptureStatus) override;
+
+  void Shutdown() override;
+
+  void Terminated() override;
+
+  void OnSetSessionId(uint32_t aCreateSessionToken,
+                      const nsAString& aSessionId) override;
+
+  void OnResolveLoadSessionPromise(uint32_t aPromiseId, bool aSuccess) override;
+
+  void OnSessionMessage(const nsAString& aSessionId,
+                        dom::MediaKeyMessageType aMessageType,
+                        const nsTArray<uint8_t>& aMessage) override;
+
+  void OnExpirationChange(const nsAString& aSessionId,
+                          UnixTime aExpiryTime) override;
+
+  void OnSessionClosed(const nsAString& aSessionId) override;
+
+  void OnSessionError(const nsAString& aSessionId, nsresult aException,
+                      uint32_t aSystemCode, const nsAString& aMsg) override;
+
+  void OnRejectPromise(uint32_t aPromiseId, ErrorResult&& aException,
+                       const nsCString& aMsg) override;
+
+  RefPtr<DecryptPromise> Decrypt(MediaRawData* aSample) override;
+  void OnDecrypted(uint32_t aId, DecryptStatus aResult,
+                   const nsTArray<uint8_t>& aDecryptedData) override;
+
+  void RejectPromise(PromiseId aId, ErrorResult&& aException,
+                     const nsCString& aReason) override;
+  // Reject promise with an InvalidStateError and the given message.
+  void RejectPromiseWithStateError(PromiseId aId, const nsCString& aReason);
+
+  // Resolves promise with "undefined".
+  // Can be called from any thread.
+  void ResolvePromise(PromiseId aId) override;
+
+  void OnKeyStatusesChange(const nsAString& aSessionId) override;
+
+  void GetStatusForPolicy(PromiseId aPromiseId,
+                          const nsAString& aMinHdcpVersion) override;
+
+#ifdef DEBUG
+  bool IsOnOwnerThread() override;
+#endif
+
+  const nsString& GetMediaDrmStubId() const;
+
+ private:
+  virtual ~MediaDrmCDMProxy();
+
+  void OnCDMCreated(uint32_t aPromiseId);
+
+  template <typename T>
+  void ResolvePromiseWithResult(PromiseId aId, const T& aResult);
+
+  struct CreateSessionData {
+    MediaKeySessionType mSessionType;
+    uint32_t mCreateSessionToken;
+    PromiseId mPromiseId;
+    nsCString mInitDataType;
+    nsTArray<uint8_t> mInitData;
+  };
+
+  struct UpdateSessionData {
+    PromiseId mPromiseId;
+    nsCString mSessionId;
+    nsTArray<uint8_t> mResponse;
+  };
+
+  struct SessionOpData {
+    PromiseId mPromiseId;
+    nsCString mSessionId;
+  };
+
+  class RejectPromiseTask : public Runnable {
+   public:
+    RejectPromiseTask(MediaDrmCDMProxy* aProxy, PromiseId aId,
+                      ErrorResult&& aException, const nsCString& aReason)
+        : Runnable("RejectPromiseTask"),
+          mProxy(aProxy),
+          mId(aId),
+          mException(std::move(aException)),
+          mReason(aReason) {}
+    NS_IMETHOD Run() override {
+      // Moving into or out of a non-copyable ErrorResult will assert that both
+      // ErorResults are from our current thread.  Avoid the assertion by moving
+      // into a current-thread CopyableErrorResult first.  Note that this is
+      // safe, because CopyableErrorResult never holds state that can't move
+      // across threads.
+      CopyableErrorResult rv(std::move(mException));
+      mProxy->RejectPromise(mId, std::move(rv), mReason);
+      return NS_OK;
+    }
+
+   private:
+    RefPtr<MediaDrmCDMProxy> mProxy;
+    PromiseId mId;
+    // We use a CopyableErrorResult here, because we're going to dispatch to a
+    // different thread and normal ErrorResult doesn't support that.
+    // CopyableErrorResult ensures that it only stores values that are safe to
+    // move across threads.
+    CopyableErrorResult mException;
+    nsCString mReason;
+  };
+
+  nsCString mNodeId;
+  UniquePtr<MediaDrmProxySupport> mCDM;
+  bool mShutdownCalled;
+
+  // =====================================================================
+  // For MediaDrmProxySupport
+  void md_Init(uint32_t aPromiseId);
+  void md_CreateSession(UniquePtr<CreateSessionData>&& aData);
+  void md_SetServerCertificate(PromiseId aPromiseId,
+                               const nsTArray<uint8_t>& aCert);
+  void md_UpdateSession(UniquePtr<UpdateSessionData>&& aData);
+  void md_CloseSession(UniquePtr<SessionOpData>&& aData);
+  void md_Shutdown();
+  // =====================================================================
+};
+
+}  // namespace mozilla
+
+#endif  // MediaDrmCDMProxy_h_
diff --git a/dom/media/eme/mediadrm/MediaDrmProxySupport.cpp b/dom/media/eme/mediadrm/MediaDrmProxySupport.cpp
new file mode 100644
index 0000000000..717a57df35
--- /dev/null
+++ b/dom/media/eme/mediadrm/MediaDrmProxySupport.cpp
@@ -0,0 +1,272 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 "MediaDrmProxySupport.h"
+#include "MediaDrmCDMCallbackProxy.h"
+#include "mozilla/EMEUtils.h"
+#include "mozilla/java/MediaDrmProxyNatives.h"
+#include "mozilla/java/SessionKeyInfoWrappers.h"
+#include "MediaCodec.h"  // For MediaDrm::KeyStatus
+
+namespace mozilla {
+
+LogModule* GetMDRMNLog() {
+  static LazyLogModule log("MediaDrmProxySupport");
+  return log;
+}
+
+class MediaDrmJavaCallbacksSupport
+    : public java::MediaDrmProxy::NativeMediaDrmProxyCallbacks::Natives<
+          MediaDrmJavaCallbacksSupport> {
+ public:
+  typedef java::MediaDrmProxy::NativeMediaDrmProxyCallbacks::Natives<
+      MediaDrmJavaCallbacksSupport>
+      MediaDrmProxyNativeCallbacks;
+  using MediaDrmProxyNativeCallbacks::AttachNative;
+  using MediaDrmProxyNativeCallbacks::DisposeNative;
+
+  explicit MediaDrmJavaCallbacksSupport(
+      UniquePtr<MediaDrmCDMCallbackProxy>&& aDecryptorProxyCallback)
+      : mDecryptorProxyCallback(std::move(aDecryptorProxyCallback)) {
+    MOZ_ASSERT(mDecryptorProxyCallback);
+  }
+  /*
+   * Native implementation, called by Java.
+   */
+  void OnSessionCreated(int aCreateSessionToken, int aPromiseId,
+                        jni::ByteArray::Param aSessionId,
+                        jni::ByteArray::Param aRequest);
+
+  void OnSessionUpdated(int aPromiseId, jni::ByteArray::Param aSessionId);
+
+  void OnSessionClosed(int aPromiseId, jni::ByteArray::Param aSessionId);
+
+  void OnSessionMessage(
+      jni::ByteArray::Param aSessionId,
+      int /*mozilla::dom::MediaKeyMessageType*/ aSessionMessageType,
+      jni::ByteArray::Param aRequest);
+
+  void OnSessionError(jni::ByteArray::Param aSessionId,
+                      jni::String::Param aMessage);
+
+  void OnSessionBatchedKeyChanged(jni::ByteArray::Param,
+                                  jni::ObjectArray::Param);
+
+  void OnRejectPromise(int aPromiseId, jni::String::Param aMessage);
+
+ private:
+  UniquePtr<MediaDrmCDMCallbackProxy> mDecryptorProxyCallback;
+};  // MediaDrmJavaCallbacksSupport
+
+void MediaDrmJavaCallbacksSupport::OnSessionCreated(
+    int aCreateSessionToken, int aPromiseId, jni::ByteArray::Param aSessionId,
+    jni::ByteArray::Param aRequest) {
+  MOZ_ASSERT(NS_IsMainThread());
+  auto reqDataArray = aRequest->GetElements();
+  nsCString sessionId(
+      reinterpret_cast<char*>(aSessionId->GetElements().Elements()),
+      aSessionId->Length());
+  MDRMN_LOG("SessionId(%s) closed", sessionId.get());
+
+  mDecryptorProxyCallback->SetSessionId(aCreateSessionToken, sessionId);
+  mDecryptorProxyCallback->ResolvePromise(aPromiseId);
+}
+
+void MediaDrmJavaCallbacksSupport::OnSessionUpdated(
+    int aPromiseId, jni::ByteArray::Param aSessionId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MDRMN_LOG(
+      "SessionId(%s) closed",
+      nsCString(reinterpret_cast<char*>(aSessionId->GetElements().Elements()),
+                aSessionId->Length())
+          .get());
+  mDecryptorProxyCallback->ResolvePromise(aPromiseId);
+}
+
+void MediaDrmJavaCallbacksSupport::OnSessionClosed(
+    int aPromiseId, jni::ByteArray::Param aSessionId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  nsCString sessionId(
+      reinterpret_cast<char*>(aSessionId->GetElements().Elements()),
+      aSessionId->Length());
+  MDRMN_LOG("SessionId(%s) closed", sessionId.get());
+  mDecryptorProxyCallback->ResolvePromise(aPromiseId);
+  mDecryptorProxyCallback->SessionClosed(sessionId);
+}
+
+void MediaDrmJavaCallbacksSupport::OnSessionMessage(
+    jni::ByteArray::Param aSessionId,
+    int /*mozilla::dom::MediaKeyMessageType*/ aMessageType,
+    jni::ByteArray::Param aRequest) {
+  MOZ_ASSERT(NS_IsMainThread());
+  nsCString sessionId(
+      reinterpret_cast<char*>(aSessionId->GetElements().Elements()),
+      aSessionId->Length());
+  auto reqDataArray = aRequest->GetElements();
+
+  nsTArray<uint8_t> retRequest;
+  retRequest.AppendElements(reinterpret_cast<uint8_t*>(reqDataArray.Elements()),
+                            reqDataArray.Length());
+
+  mDecryptorProxyCallback->SessionMessage(
+      sessionId, static_cast<dom::MediaKeyMessageType>(aMessageType),
+      retRequest);
+}
+
+void MediaDrmJavaCallbacksSupport::OnSessionError(
+    jni::ByteArray::Param aSessionId, jni::String::Param aMessage) {
+  MOZ_ASSERT(NS_IsMainThread());
+  nsCString sessionId(
+      reinterpret_cast<char*>(aSessionId->GetElements().Elements()),
+      aSessionId->Length());
+  nsCString errorMessage = aMessage->ToCString();
+  MDRMN_LOG("SessionId(%s)", sessionId.get());
+  // TODO: We cannot get system error code from media drm API.
+  // Currently use -1 as an error code.
+  mDecryptorProxyCallback->SessionError(
+      sessionId, NS_ERROR_DOM_INVALID_STATE_ERR, -1, errorMessage);
+}
+
+// TODO: MediaDrm.KeyStatus defined the status code not included
+// dom::MediaKeyStatus::Released and dom::MediaKeyStatus::Output_downscaled.
+// Should keep tracking for this if it will be changed in the future.
+static dom::MediaKeyStatus MediaDrmKeyStatusToMediaKeyStatus(int aStatusCode) {
+  using mozilla::java::sdk::MediaDrm;
+  switch (aStatusCode) {
+    case MediaDrm::KeyStatus::STATUS_USABLE:
+      return dom::MediaKeyStatus::Usable;
+    case MediaDrm::KeyStatus::STATUS_EXPIRED:
+      return dom::MediaKeyStatus::Expired;
+    case MediaDrm::KeyStatus::STATUS_OUTPUT_NOT_ALLOWED:
+      return dom::MediaKeyStatus::Output_restricted;
+    case MediaDrm::KeyStatus::STATUS_INTERNAL_ERROR:
+      return dom::MediaKeyStatus::Internal_error;
+    case MediaDrm::KeyStatus::STATUS_PENDING:
+      return dom::MediaKeyStatus::Status_pending;
+    default:
+      return dom::MediaKeyStatus::Internal_error;
+  }
+}
+
+void MediaDrmJavaCallbacksSupport::OnSessionBatchedKeyChanged(
+    jni::ByteArray::Param aSessionId, jni::ObjectArray::Param aKeyInfos) {
+  MOZ_ASSERT(NS_IsMainThread());
+  nsCString sessionId(
+      reinterpret_cast<char*>(aSessionId->GetElements().Elements()),
+      aSessionId->Length());
+  nsTArray<jni::Object::LocalRef> keyInfosObjectArray(aKeyInfos->GetElements());
+
+  nsTArray<CDMKeyInfo> keyInfosArray;
+
+  for (auto&& keyInfoObject : keyInfosObjectArray) {
+    java::SessionKeyInfo::LocalRef keyInfo(std::move(keyInfoObject));
+    mozilla::jni::ByteArray::LocalRef keyIdByteArray = keyInfo->KeyId();
+    nsTArray<int8_t> keyIdInt8Array = keyIdByteArray->GetElements();
+    // Cast nsTArray<int8_t> to nsTArray<uint8_t>
+    nsTArray<uint8_t>* keyId =
+        reinterpret_cast<nsTArray<uint8_t>*>(&keyIdInt8Array);
+    auto keyStatus = keyInfo->Status();  // int32_t
+    keyInfosArray.AppendElement(
+        CDMKeyInfo(*keyId, dom::Optional<dom::MediaKeyStatus>(
+                               MediaDrmKeyStatusToMediaKeyStatus(keyStatus))));
+  }
+
+  mDecryptorProxyCallback->BatchedKeyStatusChanged(sessionId, keyInfosArray);
+}
+
+void MediaDrmJavaCallbacksSupport::OnRejectPromise(
+    int aPromiseId, jni::String::Param aMessage) {
+  MOZ_ASSERT(NS_IsMainThread());
+  nsCString reason = aMessage->ToCString();
+  MDRMN_LOG("OnRejectPromise aMessage(%s) ", reason.get());
+  // Current implementation assume all the reject from MediaDrm is due to
+  // invalid state. Other cases should be handled before calling into
+  // MediaDrmProxy API.
+  ErrorResult rv;
+  rv.ThrowInvalidStateError(reason);
+  mDecryptorProxyCallback->RejectPromise(aPromiseId, std::move(rv), reason);
+}
+
+MediaDrmProxySupport::MediaDrmProxySupport(const nsAString& aKeySystem)
+    : mKeySystem(aKeySystem), mDestroyed(false) {
+  mJavaCallbacks = java::MediaDrmProxy::NativeMediaDrmProxyCallbacks::New();
+
+  mBridgeProxy = java::MediaDrmProxy::Create(mKeySystem, mJavaCallbacks);
+
+  MOZ_ASSERT(mBridgeProxy, "mBridgeProxy should not be null");
+  mMediaDrmStubId = mBridgeProxy->GetStubId()->ToString();
+}
+
+MediaDrmProxySupport::~MediaDrmProxySupport() {
+  MOZ_ASSERT(mDestroyed, "Shutdown() should be called before !!");
+  MediaDrmJavaCallbacksSupport::DisposeNative(mJavaCallbacks);
+}
+
+nsresult MediaDrmProxySupport::Init(
+    UniquePtr<MediaDrmCDMCallbackProxy>&& aCallback) {
+  MOZ_ASSERT(mJavaCallbacks);
+
+  MediaDrmJavaCallbacksSupport::AttachNative(
+      mJavaCallbacks,
+      mozilla::MakeUnique<MediaDrmJavaCallbacksSupport>(std::move(aCallback)));
+  return mBridgeProxy != nullptr ? NS_OK : NS_ERROR_FAILURE;
+}
+
+void MediaDrmProxySupport::CreateSession(uint32_t aCreateSessionToken,
+                                         uint32_t aPromiseId,
+                                         const nsCString& aInitDataType,
+                                         const nsTArray<uint8_t>& aInitData,
+                                         MediaDrmSessionType aSessionType) {
+  MOZ_ASSERT(mBridgeProxy);
+
+  auto initDataBytes = mozilla::jni::ByteArray::New(
+      reinterpret_cast<const int8_t*>(&aInitData[0]), aInitData.Length());
+  // TODO: aSessionType is not used here.
+  // Refer to
+  // http://androidxref.com/5.1.1_r6/xref/external/chromium_org/media/base/android/java/src/org/chromium/media/MediaDrmBridge.java#420
+  // it is hard code to streaming type.
+  mBridgeProxy->CreateSession(aCreateSessionToken, aPromiseId,
+                              NS_ConvertUTF8toUTF16(aInitDataType),
+                              initDataBytes);
+}
+
+void MediaDrmProxySupport::UpdateSession(uint32_t aPromiseId,
+                                         const nsCString& aSessionId,
+                                         const nsTArray<uint8_t>& aResponse) {
+  MOZ_ASSERT(mBridgeProxy);
+
+  auto response = mozilla::jni::ByteArray::New(
+      reinterpret_cast<const int8_t*>(aResponse.Elements()),
+      aResponse.Length());
+  mBridgeProxy->UpdateSession(aPromiseId, NS_ConvertUTF8toUTF16(aSessionId),
+                              response);
+}
+
+void MediaDrmProxySupport::CloseSession(uint32_t aPromiseId,
+                                        const nsCString& aSessionId) {
+  MOZ_ASSERT(mBridgeProxy);
+
+  mBridgeProxy->CloseSession(aPromiseId, NS_ConvertUTF8toUTF16(aSessionId));
+}
+
+void MediaDrmProxySupport::Shutdown() {
+  MOZ_ASSERT(mBridgeProxy);
+
+  if (mDestroyed) {
+    return;
+  }
+  mBridgeProxy->Destroy();
+  mDestroyed = true;
+}
+
+bool MediaDrmProxySupport::SetServerCertificate(
+    const nsTArray<uint8_t>& aCert) {
+  jni::ByteArray::LocalRef cert = jni::ByteArray::New(
+      reinterpret_cast<const int8_t*>(aCert.Elements()), aCert.Length());
+  return mBridgeProxy->SetServerCertificate(cert);
+}
+
+}  // namespace mozilla
diff --git a/dom/media/eme/mediadrm/MediaDrmProxySupport.h b/dom/media/eme/mediadrm/MediaDrmProxySupport.h
new file mode 100644
index 0000000000..e994036f69
--- /dev/null
+++ b/dom/media/eme/mediadrm/MediaDrmProxySupport.h
@@ -0,0 +1,68 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef MediaDrmProxySupport_H
+#define MediaDrmProxySupport_H
+
+#include "mozilla/DecryptorProxyCallback.h"
+#include "mozilla/java/MediaDrmProxyWrappers.h"
+#include "mozilla/Logging.h"
+#include "mozilla/UniquePtr.h"
+#include "nsString.h"
+
+namespace mozilla {
+
+enum MediaDrmSessionType {
+  kKeyStreaming = 1,
+  kKeyOffline = 2,
+  kKeyRelease = 3,
+};
+
+#ifndef MDRMN_LOG
+LogModule* GetMDRMNLog();
+#  define MDRMN_LOG(x, ...)                          \
+    MOZ_LOG(GetMDRMNLog(), mozilla::LogLevel::Debug, \
+            ("[MediaDrmProxySupport][%s]" x, __FUNCTION__, ##__VA_ARGS__))
+#endif
+
+class MediaDrmCDMCallbackProxy;
+
+class MediaDrmProxySupport final {
+ public:
+  explicit MediaDrmProxySupport(const nsAString& aKeySystem);
+  ~MediaDrmProxySupport();
+
+  /*
+   * APIs to act as GMPDecryptorAPI, discarding unnecessary calls.
+   */
+  nsresult Init(UniquePtr<MediaDrmCDMCallbackProxy>&& aCallback);
+
+  void CreateSession(uint32_t aCreateSessionToken, uint32_t aPromiseId,
+                     const nsCString& aInitDataType,
+                     const nsTArray<uint8_t>& aInitData,
+                     MediaDrmSessionType aSessionType);
+
+  void UpdateSession(uint32_t aPromiseId, const nsCString& aSessionId,
+                     const nsTArray<uint8_t>& aResponse);
+
+  void CloseSession(uint32_t aPromiseId, const nsCString& aSessionId);
+
+  void Shutdown();
+
+  const nsString& GetMediaDrmStubId() const { return mMediaDrmStubId; }
+
+  bool SetServerCertificate(const nsTArray<uint8_t>& aCert);
+
+ private:
+  const nsString mKeySystem;
+  java::MediaDrmProxy::GlobalRef mBridgeProxy;
+  java::MediaDrmProxy::NativeMediaDrmProxyCallbacks::GlobalRef mJavaCallbacks;
+  bool mDestroyed;
+  nsString mMediaDrmStubId;
+};
+
+}  // namespace mozilla
+#endif  // MediaDrmProxySupport_H
diff --git a/dom/media/eme/mediadrm/moz.build b/dom/media/eme/mediadrm/moz.build
new file mode 100644
index 0000000000..c8f433f25f
--- /dev/null
+++ b/dom/media/eme/mediadrm/moz.build
@@ -0,0 +1,19 @@
+# -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+EXPORTS.mozilla += [
+    "MediaDrmCDMCallbackProxy.h",
+    "MediaDrmCDMProxy.h",
+    "MediaDrmProxySupport.h",
+]
+
+UNIFIED_SOURCES += [
+    "MediaDrmCDMCallbackProxy.cpp",
+    "MediaDrmCDMProxy.cpp",
+    "MediaDrmProxySupport.cpp",
+]
+
+FINAL_LIBRARY = "xul"
diff --git a/dom/media/eme/mediafoundation/WMFCDMImpl.cpp b/dom/media/eme/mediafoundation/WMFCDMImpl.cpp
new file mode 100644
index 0000000000..c2ca31bf15
--- /dev/null
+++ b/dom/media/eme/mediafoundation/WMFCDMImpl.cpp
@@ -0,0 +1,128 @@
+/* -*- 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 "WMFCDMImpl.h"
+
+#include "mozilla/dom/MediaKeySession.h"
+
+namespace mozilla {
+
+/* static */
+bool WMFCDMImpl::Supports(const nsAString& aKeySystem) {
+  static std::map<nsString, bool> supports;
+
+  nsString key(aKeySystem);
+  if (const auto& s = supports.find(key); s != supports.end()) {
+    return s->second;
+  }
+
+  RefPtr<WMFCDMImpl> cdm = MakeRefPtr<WMFCDMImpl>(aKeySystem);
+  KeySystemConfig c;
+  bool s = cdm->GetCapabilities(c);
+  supports[key] = s;
+
+  return s;
+}
+
+static void MFCDMCapabilitiesIPDLToKeySystemConfig(
+    const MFCDMCapabilitiesIPDL& aCDMConfig,
+    KeySystemConfig& aKeySystemConfig) {
+  aKeySystemConfig.mKeySystem = aCDMConfig.keySystem();
+
+  for (const auto& type : aCDMConfig.initDataTypes()) {
+    aKeySystemConfig.mInitDataTypes.AppendElement(type);
+  }
+
+  for (const auto& type : aCDMConfig.sessionTypes()) {
+    aKeySystemConfig.mSessionTypes.AppendElement(type);
+  }
+
+  for (const auto& c : aCDMConfig.videoCapabilities()) {
+    if (!c.robustness().IsEmpty() &&
+        !aKeySystemConfig.mVideoRobustness.Contains(c.robustness())) {
+      aKeySystemConfig.mVideoRobustness.AppendElement(c.robustness());
+    }
+    aKeySystemConfig.mMP4.SetCanDecryptAndDecode(
+        NS_ConvertUTF16toUTF8(c.contentType()));
+  }
+  for (const auto& c : aCDMConfig.audioCapabilities()) {
+    if (!c.robustness().IsEmpty() &&
+        !aKeySystemConfig.mAudioRobustness.Contains(c.robustness())) {
+      aKeySystemConfig.mAudioRobustness.AppendElement(c.robustness());
+    }
+    aKeySystemConfig.mMP4.SetCanDecryptAndDecode(
+        NS_ConvertUTF16toUTF8(c.contentType()));
+  }
+  aKeySystemConfig.mPersistentState = aCDMConfig.persistentState();
+  aKeySystemConfig.mDistinctiveIdentifier = aCDMConfig.distinctiveID();
+}
+
+static const char* EncryptionSchemeStr(const CryptoScheme aScheme) {
+  switch (aScheme) {
+    case CryptoScheme::None:
+      return "none";
+    case CryptoScheme::Cenc:
+      return "cenc";
+    case CryptoScheme::Cbcs:
+      return "cbcs";
+  }
+}
+
+bool WMFCDMImpl::GetCapabilities(KeySystemConfig& aConfig) {
+  nsCOMPtr<nsISerialEventTarget> backgroundTaskQueue;
+  NS_CreateBackgroundTaskQueue(__func__, getter_AddRefs(backgroundTaskQueue));
+
+  bool ok = false;
+  media::Await(
+      backgroundTaskQueue.forget(), mCDM->GetCapabilities(),
+      [&ok, &aConfig](const MFCDMCapabilitiesIPDL& capabilities) {
+        EME_LOG("capabilities: keySystem=%s",
+                NS_ConvertUTF16toUTF8(capabilities.keySystem()).get());
+        for (const auto& v : capabilities.videoCapabilities()) {
+          EME_LOG("capabilities: video=%s",
+                  NS_ConvertUTF16toUTF8(v.contentType()).get());
+        }
+        for (const auto& a : capabilities.audioCapabilities()) {
+          EME_LOG("capabilities: audio=%s",
+                  NS_ConvertUTF16toUTF8(a.contentType()).get());
+        }
+        for (const auto& v : capabilities.encryptionSchemes()) {
+          EME_LOG("capabilities: encryptionScheme=%s", EncryptionSchemeStr(v));
+        }
+        MFCDMCapabilitiesIPDLToKeySystemConfig(capabilities, aConfig);
+        ok = true;
+      },
+      [](nsresult rv) {
+        EME_LOG("Fail to get key system capabilities. rv=%x", rv);
+      });
+  return ok;
+}
+
+RefPtr<WMFCDMImpl::InitPromise> WMFCDMImpl::Init(
+    const WMFCDMImpl::InitParams& aParams) {
+  MOZ_ASSERT(mCDM);
+
+  RefPtr<WMFCDMImpl> self = this;
+  mCDM->Init(aParams.mOrigin, aParams.mInitDataTypes,
+             aParams.mPersistentStateRequired
+                 ? KeySystemConfig::Requirement::Required
+                 : KeySystemConfig::Requirement::Optional,
+             aParams.mDistinctiveIdentifierRequired
+                 ? KeySystemConfig::Requirement::Required
+                 : KeySystemConfig::Requirement::Optional,
+             aParams.mHWSecure, aParams.mProxyCallback)
+      ->Then(
+          mCDM->ManagerThread(), __func__,
+          [self, this](const MFCDMInitIPDL& init) {
+            mInitPromiseHolder.ResolveIfExists(true, __func__);
+          },
+          [self, this](const nsresult rv) {
+            mInitPromiseHolder.RejectIfExists(rv, __func__);
+          });
+  return mInitPromiseHolder.Ensure(__func__);
+}
+
+}  // namespace mozilla
diff --git a/dom/media/eme/mediafoundation/WMFCDMImpl.h b/dom/media/eme/mediafoundation/WMFCDMImpl.h
new file mode 100644
index 0000000000..fc4ef840d6
--- /dev/null
+++ b/dom/media/eme/mediafoundation/WMFCDMImpl.h
@@ -0,0 +1,100 @@
+/* -*- 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/. */
+
+#ifndef DOM_MEDIA_EME_MEDIAFOUNDATION_WMFCDMIMPL_H_
+#define DOM_MEDIA_EME_MEDIAFOUNDATION_WMFCDMIMPL_H_
+
+#include "MediaData.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/EMEUtils.h"
+#include "mozilla/KeySystemConfig.h"
+#include "mozilla/media/MediaUtils.h"
+#include "mozilla/MFCDMChild.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+
+class WMFCDMProxyCallback;
+
+/**
+ * WMFCDMImpl is a helper class for MFCDM protocol clients. It creates, manages,
+ * and calls MFCDMChild object in the content process on behalf of the client,
+ * and performs conversion between EME and MFCDM types and constants.
+ */
+class WMFCDMImpl final {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(WMFCDMImpl);
+
+  explicit WMFCDMImpl(const nsAString& aKeySystem)
+      : mCDM(MakeRefPtr<MFCDMChild>(aKeySystem)) {}
+
+  static bool Supports(const nsAString& aKeySystem);
+  // TODO: make this async?
+  bool GetCapabilities(KeySystemConfig& aConfig);
+
+  using InitPromise = GenericPromise;
+  struct InitParams {
+    nsString mOrigin;
+    CopyableTArray<nsString> mInitDataTypes;
+    bool mPersistentStateRequired;
+    bool mDistinctiveIdentifierRequired;
+    bool mHWSecure;
+    WMFCDMProxyCallback* mProxyCallback;
+  };
+
+  RefPtr<InitPromise> Init(const InitParams& aParams);
+
+  RefPtr<MFCDMChild::SessionPromise> CreateSession(
+      uint32_t aPromiseId, const KeySystemConfig::SessionType aSessionType,
+      const nsAString& aInitDataType, const nsTArray<uint8_t>& aInitData) {
+    return mCDM->CreateSessionAndGenerateRequest(aPromiseId, aSessionType,
+                                                 aInitDataType, aInitData);
+  }
+
+  RefPtr<GenericPromise> LoadSession(
+      uint32_t aPromiseId, const KeySystemConfig::SessionType aSessionType,
+      const nsAString& aSessionId) {
+    return mCDM->LoadSession(aPromiseId, aSessionType, aSessionId);
+  }
+
+  RefPtr<GenericPromise> UpdateSession(uint32_t aPromiseId,
+                                       const nsAString& aSessionId,
+                                       nsTArray<uint8_t>& aResponse) {
+    return mCDM->UpdateSession(aPromiseId, aSessionId, aResponse);
+  }
+
+  RefPtr<GenericPromise> CloseSession(uint32_t aPromiseId,
+                                      const nsAString& aSessionId) {
+    return mCDM->CloseSession(aPromiseId, aSessionId);
+  }
+
+  RefPtr<GenericPromise> RemoveSession(uint32_t aPromiseId,
+                                       const nsAString& aSessionId) {
+    return mCDM->RemoveSession(aPromiseId, aSessionId);
+  }
+
+  uint64_t Id() {
+    MOZ_ASSERT(mCDM->Id() != 0,
+               "Should be called only after Init() is resolved");
+    return mCDM->Id();
+  }
+
+ private:
+  ~WMFCDMImpl() {
+    if (mCDM) {
+      mCDM->Shutdown();
+    }
+  };
+
+  const RefPtr<MFCDMChild> mCDM;
+
+  MozPromiseHolder<InitPromise> mInitPromiseHolder;
+};
+
+}  // namespace mozilla
+
+#endif  // DOM_MEDIA_EME_MEDIAFOUNDATION_WMFCDMIMPL_H_
diff --git a/dom/media/eme/mediafoundation/WMFCDMProxy.cpp b/dom/media/eme/mediafoundation/WMFCDMProxy.cpp
new file mode 100644
index 0000000000..1d691168d8
--- /dev/null
+++ b/dom/media/eme/mediafoundation/WMFCDMProxy.cpp
@@ -0,0 +1,306 @@
+/* -*- 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 "WMFCDMProxy.h"
+
+#include "mozilla/dom/MediaKeySession.h"
+#include "mozilla/WMFCDMProxyCallback.h"
+#include "WMFCDMImpl.h"
+#include "WMFCDMProxyCallback.h"
+
+namespace mozilla {
+
+#define LOG(msg, ...) \
+  EME_LOG("WMFCDMProxy[%p]@%s: " msg, this, __func__, ##__VA_ARGS__)
+
+#define RETURN_IF_SHUTDOWN()       \
+  do {                             \
+    MOZ_ASSERT(NS_IsMainThread()); \
+    if (mIsShutdown) {             \
+      return;                      \
+    }                              \
+  } while (false)
+
+#define PERFORM_ON_CDM(operation, promiseId, ...)                             \
+  do {                                                                        \
+    mCDM->operation(promiseId, __VA_ARGS__)                                   \
+        ->Then(                                                               \
+            mMainThread, __func__,                                            \
+            [self = RefPtr{this}, this, promiseId]() {                        \
+              RETURN_IF_SHUTDOWN();                                           \
+              if (mKeys.IsNull()) {                                           \
+                EME_LOG("WMFCDMProxy(this=%p, pid=%" PRIu32                   \
+                        ") : abort the " #operation " due to empty key",      \
+                        this, promiseId);                                     \
+                return;                                                       \
+              }                                                               \
+              ResolvePromise(promiseId);                                      \
+            },                                                                \
+            [self = RefPtr{this}, this, promiseId]() {                        \
+              RETURN_IF_SHUTDOWN();                                           \
+              RejectPromiseWithStateError(                                    \
+                  promiseId, nsLiteralCString("WMFCDMProxy::" #operation ": " \
+                                              "failed to " #operation));      \
+            });                                                               \
+  } while (false)
+
+WMFCDMProxy::WMFCDMProxy(dom::MediaKeys* aKeys, const nsAString& aKeySystem,
+                         const dom::MediaKeySystemConfiguration& aConfig)
+    : CDMProxy(
+          aKeys, aKeySystem,
+          aConfig.mDistinctiveIdentifier == dom::MediaKeysRequirement::Required,
+          aConfig.mPersistentState == dom::MediaKeysRequirement::Required),
+      mConfig(aConfig) {
+  MOZ_ASSERT(NS_IsMainThread());
+}
+
+WMFCDMProxy::~WMFCDMProxy() {}
+
+void WMFCDMProxy::Init(PromiseId aPromiseId, const nsAString& aOrigin,
+                       const nsAString& aTopLevelOrigin,
+                       const nsAString& aName) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!aOrigin.IsEmpty());
+
+  MOZ_ASSERT(!mOwnerThread);
+  if (NS_FAILED(
+          NS_NewNamedThread("WMFCDMThread", getter_AddRefs(mOwnerThread)))) {
+    RejectPromiseWithStateError(
+        aPromiseId,
+        nsLiteralCString("WMFCDMProxy::Init: couldn't create CDM thread"));
+    return;
+  }
+
+  mCDM = MakeRefPtr<WMFCDMImpl>(mKeySystem);
+  mProxyCallback = new WMFCDMProxyCallback(this);
+  WMFCDMImpl::InitParams params{nsString(aOrigin),
+                                mConfig.mInitDataTypes,
+                                mPersistentStateRequired,
+                                mDistinctiveIdentifierRequired,
+                                false /* TODO : support HW secure */,
+                                mProxyCallback};
+  mCDM->Init(params)->Then(
+      mMainThread, __func__,
+      [self = RefPtr{this}, this, aPromiseId](const bool) {
+        MOZ_ASSERT(mCDM->Id() > 0);
+        mKeys->OnCDMCreated(aPromiseId, mCDM->Id());
+      },
+      [self = RefPtr{this}, this, aPromiseId](const nsresult rv) {
+        RejectPromiseWithStateError(
+            aPromiseId,
+            nsLiteralCString("WMFCDMProxy::Init: WMFCDM init error"));
+      });
+}
+
+void WMFCDMProxy::ResolvePromise(PromiseId aId) {
+  auto resolve = [self = RefPtr{this}, this, aId]() {
+    RETURN_IF_SHUTDOWN();
+    EME_LOG("WMFCDMProxy::ResolvePromise(this=%p, pid=%" PRIu32 ")", this, aId);
+    if (!mKeys.IsNull()) {
+      mKeys->ResolvePromise(aId);
+    } else {
+      NS_WARNING("WMFCDMProxy unable to resolve promise!");
+    }
+  };
+
+  if (NS_IsMainThread()) {
+    resolve();
+    return;
+  }
+  mMainThread->Dispatch(
+      NS_NewRunnableFunction("WMFCDMProxy::ResolvePromise", resolve));
+}
+
+void WMFCDMProxy::RejectPromise(PromiseId aId, ErrorResult&& aException,
+                                const nsCString& aReason) {
+  if (!NS_IsMainThread()) {
+    // Use CopyableErrorResult to store our exception in the runnable,
+    // because ErrorResult is not OK to move across threads.
+    mMainThread->Dispatch(
+        NewRunnableMethod<PromiseId, StoreCopyPassByRRef<CopyableErrorResult>,
+                          nsCString>("WMFCDMProxy::RejectPromise", this,
+                                     &WMFCDMProxy::RejectPromiseOnMainThread,
+                                     aId, std::move(aException), aReason),
+        NS_DISPATCH_NORMAL);
+    return;
+  }
+  EME_LOG("WMFCDMProxy::RejectPromise(this=%p, pid=%" PRIu32
+          ", code=0x%x, "
+          "reason='%s')",
+          this, aId, aException.ErrorCodeAsInt(), aReason.get());
+  if (!mKeys.IsNull()) {
+    mKeys->RejectPromise(aId, std::move(aException), aReason);
+  } else {
+    // We don't have a MediaKeys object to pass the exception to, so silence
+    // the exception to avoid it asserting due to being unused.
+    aException.SuppressException();
+  }
+}
+
+void WMFCDMProxy::RejectPromiseOnMainThread(PromiseId aId,
+                                            CopyableErrorResult&& aException,
+                                            const nsCString& aReason) {
+  RETURN_IF_SHUTDOWN();
+  // Moving into or out of a non-copyable ErrorResult will assert that both
+  // ErorResults are from our current thread.  Avoid the assertion by moving
+  // into a current-thread CopyableErrorResult first.  Note that this is safe,
+  // because CopyableErrorResult never holds state that can't move across
+  // threads.
+  CopyableErrorResult rv(std::move(aException));
+  RejectPromise(aId, std::move(rv), aReason);
+}
+
+void WMFCDMProxy::RejectPromiseWithStateError(PromiseId aId,
+                                              const nsCString& aReason) {
+  ErrorResult rv;
+  rv.ThrowInvalidStateError(aReason);
+  RejectPromise(aId, std::move(rv), aReason);
+}
+
+void WMFCDMProxy::CreateSession(uint32_t aCreateSessionToken,
+                                MediaKeySessionType aSessionType,
+                                PromiseId aPromiseId,
+                                const nsAString& aInitDataType,
+                                nsTArray<uint8_t>& aInitData) {
+  MOZ_ASSERT(NS_IsMainThread());
+  RETURN_IF_SHUTDOWN();
+  const auto sessionType = ConvertToKeySystemConfigSessionType(aSessionType);
+  EME_LOG("WMFCDMProxy::CreateSession(this=%p, pid=%" PRIu32
+          "), sessionType=%s",
+          this, aPromiseId, SessionTypeToStr(sessionType));
+  mCDM->CreateSession(aPromiseId, sessionType, aInitDataType, aInitData)
+      ->Then(
+          mMainThread, __func__,
+          [self = RefPtr{this}, this, aCreateSessionToken,
+           aPromiseId](nsString sessionID) {
+            RETURN_IF_SHUTDOWN();
+            if (mKeys.IsNull()) {
+              EME_LOG("WMFCDMProxy(this=%p, pid=%" PRIu32
+                      ") : abort the create session due to "
+                      "empty key",
+                      this, aPromiseId);
+              return;
+            }
+            if (RefPtr<dom::MediaKeySession> session =
+                    mKeys->GetPendingSession(aCreateSessionToken)) {
+              session->SetSessionId(std::move(sessionID));
+            }
+            ResolvePromise(aPromiseId);
+          },
+          [self = RefPtr{this}, this, aPromiseId]() {
+            RETURN_IF_SHUTDOWN();
+            RejectPromiseWithStateError(
+                aPromiseId,
+                nsLiteralCString(
+                    "WMFCDMProxy::CreateSession: cannot create session"));
+          });
+}
+
+void WMFCDMProxy::LoadSession(PromiseId aPromiseId,
+                              dom::MediaKeySessionType aSessionType,
+                              const nsAString& aSessionId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  RETURN_IF_SHUTDOWN();
+  const auto sessionType = ConvertToKeySystemConfigSessionType(aSessionType);
+  EME_LOG("WMFCDMProxy::LoadSession(this=%p, pid=%" PRIu32
+          "), sessionType=%s, sessionId=%s",
+          this, aPromiseId, SessionTypeToStr(sessionType),
+          NS_ConvertUTF16toUTF8(aSessionId).get());
+  PERFORM_ON_CDM(LoadSession, aPromiseId, sessionType, aSessionId);
+}
+
+void WMFCDMProxy::UpdateSession(const nsAString& aSessionId,
+                                PromiseId aPromiseId,
+                                nsTArray<uint8_t>& aResponse) {
+  MOZ_ASSERT(NS_IsMainThread());
+  RETURN_IF_SHUTDOWN();
+  EME_LOG("WMFCDMProxy::UpdateSession(this=%p, pid=%" PRIu32
+          "), sessionId=%s, responseLen=%zu",
+          this, aPromiseId, NS_ConvertUTF16toUTF8(aSessionId).get(),
+          aResponse.Length());
+  PERFORM_ON_CDM(UpdateSession, aPromiseId, aSessionId, aResponse);
+}
+
+void WMFCDMProxy::CloseSession(const nsAString& aSessionId,
+                               PromiseId aPromiseId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  RETURN_IF_SHUTDOWN();
+  EME_LOG("WMFCDMProxy::CloseSession(this=%p, pid=%" PRIu32 "), sessionId=%s",
+          this, aPromiseId, NS_ConvertUTF16toUTF8(aSessionId).get());
+  PERFORM_ON_CDM(CloseSession, aPromiseId, aSessionId);
+}
+
+void WMFCDMProxy::RemoveSession(const nsAString& aSessionId,
+                                PromiseId aPromiseId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  RETURN_IF_SHUTDOWN();
+  EME_LOG("WMFCDMProxy::RemoveSession(this=%p, pid=%" PRIu32 "), sessionId=%s",
+          this, aPromiseId, NS_ConvertUTF16toUTF8(aSessionId).get());
+  PERFORM_ON_CDM(RemoveSession, aPromiseId, aSessionId);
+}
+
+void WMFCDMProxy::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!mIsShutdown);
+  if (mProxyCallback) {
+    mProxyCallback->Shutdown();
+    mProxyCallback = nullptr;
+  }
+  mIsShutdown = true;
+}
+
+void WMFCDMProxy::OnSessionMessage(const nsAString& aSessionId,
+                                   dom::MediaKeyMessageType aMessageType,
+                                   const nsTArray<uint8_t>& aMessage) {
+  MOZ_ASSERT(NS_IsMainThread());
+  RETURN_IF_SHUTDOWN();
+  if (mKeys.IsNull()) {
+    return;
+  }
+  if (RefPtr<dom::MediaKeySession> session = mKeys->GetSession(aSessionId)) {
+    LOG("Notify key message for session Id=%s",
+        NS_ConvertUTF16toUTF8(aSessionId).get());
+    session->DispatchKeyMessage(aMessageType, aMessage);
+  }
+}
+
+void WMFCDMProxy::OnKeyStatusesChange(const nsAString& aSessionId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  RETURN_IF_SHUTDOWN();
+  if (mKeys.IsNull()) {
+    return;
+  }
+  if (RefPtr<dom::MediaKeySession> session = mKeys->GetSession(aSessionId)) {
+    LOG("Notify key statuses for session Id=%s",
+        NS_ConvertUTF16toUTF8(aSessionId).get());
+    session->DispatchKeyStatusesChange();
+  }
+}
+
+void WMFCDMProxy::OnExpirationChange(const nsAString& aSessionId,
+                                     UnixTime aExpiryTime) {
+  MOZ_ASSERT(NS_IsMainThread());
+  RETURN_IF_SHUTDOWN();
+  if (mKeys.IsNull()) {
+    return;
+  }
+  if (RefPtr<dom::MediaKeySession> session = mKeys->GetSession(aSessionId)) {
+    LOG("Notify expiration for session Id=%s",
+        NS_ConvertUTF16toUTF8(aSessionId).get());
+    session->SetExpiration(static_cast<double>(aExpiryTime));
+  }
+}
+
+uint64_t WMFCDMProxy::GetCDMProxyId() const {
+  MOZ_DIAGNOSTIC_ASSERT(mCDM);
+  return mCDM->Id();
+}
+
+#undef LOG
+#undef RETURN_IF_SHUTDOWN
+#undef PERFORM_ON_CDM
+
+}  // namespace mozilla
diff --git a/dom/media/eme/mediafoundation/WMFCDMProxy.h b/dom/media/eme/mediafoundation/WMFCDMProxy.h
new file mode 100644
index 0000000000..7766b73f21
--- /dev/null
+++ b/dom/media/eme/mediafoundation/WMFCDMProxy.h
@@ -0,0 +1,134 @@
+/* -*- 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/. */
+
+#ifndef DOM_MEDIA_EME_MEDIAFOUNDATION_WMFCDMPROXY_H_
+#define DOM_MEDIA_EME_MEDIAFOUNDATION_WMFCDMPROXY_H_
+
+#include "mozilla/CDMProxy.h"
+#include "mozilla/CDMCaps.h"
+#include "mozilla/MozPromise.h"
+#include "mozilla/dom/MediaKeys.h"
+#include "mozilla/dom/MediaKeySession.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/WMFCDMImpl.h"
+
+#include "nsString.h"
+
+namespace mozilla {
+
+class WMFCDMProxyCallback;
+
+class WMFCDMProxy : public CDMProxy {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(WMFCDMProxy, override)
+
+  WMFCDMProxy(dom::MediaKeys* aKeys, const nsAString& aKeySystem,
+              const dom::MediaKeySystemConfiguration& aConfig);
+
+  // CDMProxy interface
+  void Init(PromiseId aPromiseId, const nsAString& aOrigin,
+            const nsAString& aTopLevelOrigin, const nsAString& aName) override;
+
+  void CreateSession(uint32_t aCreateSessionToken,
+                     MediaKeySessionType aSessionType, PromiseId aPromiseId,
+                     const nsAString& aInitDataType,
+                     nsTArray<uint8_t>& aInitData) override;
+
+  void LoadSession(PromiseId aPromiseId, dom::MediaKeySessionType aSessionType,
+                   const nsAString& aSessionId) override;
+
+  void SetServerCertificate(PromiseId aPromiseId,
+                            nsTArray<uint8_t>& aCert) override {}
+
+  void UpdateSession(const nsAString& aSessionId, PromiseId aPromiseId,
+                     nsTArray<uint8_t>& aResponse) override;
+
+  void CloseSession(const nsAString& aSessionId, PromiseId aPromiseId) override;
+
+  void RemoveSession(const nsAString& aSessionId,
+                     PromiseId aPromiseId) override;
+
+  void QueryOutputProtectionStatus() override {}
+
+  void NotifyOutputProtectionStatus(
+      OutputProtectionCheckStatus aCheckStatus,
+      OutputProtectionCaptureStatus aCaptureStatus) override {}
+
+  void Shutdown() override;
+
+  void Terminated() override {}
+
+  void OnSetSessionId(uint32_t aCreateSessionToken,
+                      const nsAString& aSessionId) override {}
+
+  void OnResolveLoadSessionPromise(uint32_t aPromiseId,
+                                   bool aSuccess) override {}
+
+  void OnSessionMessage(const nsAString& aSessionId,
+                        dom::MediaKeyMessageType aMessageType,
+                        const nsTArray<uint8_t>& aMessage) override;
+
+  void OnExpirationChange(const nsAString& aSessionId,
+                          UnixTime aExpiryTime) override;
+
+  void OnSessionClosed(const nsAString& aSessionId) override {}
+
+  void OnSessionError(const nsAString& aSessionId, nsresult aException,
+                      uint32_t aSystemCode, const nsAString& aMsg) override {}
+
+  void OnRejectPromise(uint32_t aPromiseId, ErrorResult&& aException,
+                       const nsCString& aMsg) override {}
+
+  RefPtr<DecryptPromise> Decrypt(MediaRawData* aSample) override {
+    return nullptr;
+  }
+  void OnDecrypted(uint32_t aId, DecryptStatus aResult,
+                   const nsTArray<uint8_t>& aDecryptedData) override {}
+
+  void ResolvePromise(PromiseId aId) override;
+  void RejectPromise(PromiseId aId, ErrorResult&& aException,
+                     const nsCString& aReason) override;
+
+  void OnKeyStatusesChange(const nsAString& aSessionId) override;
+
+  void GetStatusForPolicy(PromiseId aPromiseId,
+                          const nsAString& aMinHdcpVersion) override {}
+
+#ifdef DEBUG
+  bool IsOnOwnerThread() override {
+    return NS_GetCurrentThread() == mOwnerThread;
+  }
+#endif
+
+  WMFCDMProxy* AsWMFCDMProxy() override { return this; }
+
+  // Can only be called after initialization succeeded.
+  uint64_t GetCDMProxyId() const;
+
+ private:
+  virtual ~WMFCDMProxy();
+
+  template <typename T>
+  void ResolvePromiseWithResult(PromiseId aId, const T& aResult) {}
+  void RejectPromiseOnMainThread(PromiseId aId,
+                                 CopyableErrorResult&& aException,
+                                 const nsCString& aReason);
+  // Reject promise with an InvalidStateError and the given message.
+  void RejectPromiseWithStateError(PromiseId aId, const nsCString& aReason);
+
+  RefPtr<WMFCDMImpl> mCDM;
+
+  const dom::MediaKeySystemConfiguration mConfig;
+
+  RefPtr<WMFCDMProxyCallback> mProxyCallback;
+
+  // It can only be used on the main thread.
+  bool mIsShutdown = false;
+};
+
+}  // namespace mozilla
+
+#endif  // DOM_MEDIA_EME_MEDIAFOUNDATION_WMFCDMPROXY_H_
diff --git a/dom/media/eme/mediafoundation/WMFCDMProxyCallback.cpp b/dom/media/eme/mediafoundation/WMFCDMProxyCallback.cpp
new file mode 100644
index 0000000000..6464cec4c7
--- /dev/null
+++ b/dom/media/eme/mediafoundation/WMFCDMProxyCallback.cpp
@@ -0,0 +1,72 @@
+/* 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 "WMFCDMProxyCallback.h"
+
+#include "mozilla/WMFCDMProxy.h"
+
+#define RETURN_IF_NULL(proxy) \
+  if (!proxy) {               \
+    return;                   \
+  }
+
+namespace mozilla {
+
+WMFCDMProxyCallback::WMFCDMProxyCallback(WMFCDMProxy* aProxy) : mProxy(aProxy) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mProxy);
+}
+
+WMFCDMProxyCallback::~WMFCDMProxyCallback() { MOZ_ASSERT(!mProxy); }
+
+void WMFCDMProxyCallback::OnSessionMessage(const MFCDMKeyMessage& aMessage) {
+  NS_DispatchToMainThread(NS_NewRunnableFunction(
+      "WMFCDMProxyCallback::OnSessionMessage",
+      [self = RefPtr{this}, this, message = aMessage]() {
+        RETURN_IF_NULL(mProxy);
+        mProxy->OnSessionMessage(message.sessionId(), message.type(),
+                                 std::move(message.message()));
+      }));
+}
+
+void WMFCDMProxyCallback::OnSessionKeyStatusesChange(
+    const MFCDMKeyStatusChange& aKeyStatuses) {
+  NS_DispatchToMainThread(NS_NewRunnableFunction(
+      "WMFCDMProxyCallback::OnSessionKeyStatusesChange",
+      [self = RefPtr{this}, this, keyStatuses = aKeyStatuses]() {
+        RETURN_IF_NULL(mProxy);
+        bool keyStatusesChange = false;
+        {
+          auto caps = mProxy->Capabilites().Lock();
+          for (const auto& keyInfo : keyStatuses.keyInfo()) {
+            keyStatusesChange |= caps->SetKeyStatus(
+                keyInfo.keyId(), keyStatuses.sessionId(),
+                dom::Optional<dom::MediaKeyStatus>(keyInfo.status()));
+          }
+        }
+        if (keyStatusesChange) {
+          mProxy->OnKeyStatusesChange(keyStatuses.sessionId());
+        }
+      }));
+}
+
+void WMFCDMProxyCallback::OnSessionKeyExpiration(
+    const MFCDMKeyExpiration& aExpiration) {
+  NS_DispatchToMainThread(NS_NewRunnableFunction(
+      "WMFCDMProxyCallback::OnSessionKeyExpiration",
+      [self = RefPtr{this}, this, expiration = aExpiration]() {
+        RETURN_IF_NULL(mProxy);
+        mProxy->OnExpirationChange(
+            expiration.sessionId(),
+            expiration.expiredTimeMilliSecondsSinceEpoch());
+      }));
+}
+
+void WMFCDMProxyCallback::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+  mProxy = nullptr;
+}
+
+#undef RETURN_IF_NULL
+}  // namespace mozilla
diff --git a/dom/media/eme/mediafoundation/WMFCDMProxyCallback.h b/dom/media/eme/mediafoundation/WMFCDMProxyCallback.h
new file mode 100644
index 0000000000..6e76f63ccc
--- /dev/null
+++ b/dom/media/eme/mediafoundation/WMFCDMProxyCallback.h
@@ -0,0 +1,38 @@
+/* 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/. */
+
+#ifndef DOM_MEDIA_EME_MEDIAFOUNDATION_WMFCDMPROXYCALLBACK_H_
+#define DOM_MEDIA_EME_MEDIAFOUNDATION_WMFCDMPROXYCALLBACK_H_
+
+#include "mozilla/PMFCDM.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+
+class WMFCDMProxy;
+
+// This class is used to notify CDM related events called from MFCDMChild, and
+// it will forward the relative calls to WMFCDMProxy on the main thread.
+class WMFCDMProxyCallback final {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(WMFCDMProxyCallback);
+
+  explicit WMFCDMProxyCallback(WMFCDMProxy* aProxy);
+
+  void OnSessionMessage(const MFCDMKeyMessage& aMessage);
+
+  void OnSessionKeyStatusesChange(const MFCDMKeyStatusChange& aKeyStatuses);
+
+  void OnSessionKeyExpiration(const MFCDMKeyExpiration& aExpiration);
+
+  void Shutdown();
+
+ private:
+  ~WMFCDMProxyCallback();
+  RefPtr<WMFCDMProxy> mProxy;
+};
+
+}  // namespace mozilla
+
+#endif  // DOM_MEDIA_EME_MEDIAFOUNDATION_WMFCDMPROXYCALLBACK_H_
diff --git a/dom/media/eme/mediafoundation/moz.build b/dom/media/eme/mediafoundation/moz.build
new file mode 100644
index 0000000000..8c54b381ff
--- /dev/null
+++ b/dom/media/eme/mediafoundation/moz.build
@@ -0,0 +1,21 @@
+# -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+EXPORTS.mozilla += [
+    "WMFCDMImpl.h",
+    "WMFCDMProxy.h",
+    "WMFCDMProxyCallback.h",
+]
+
+UNIFIED_SOURCES += [
+    "WMFCDMImpl.cpp",
+    "WMFCDMProxy.cpp",
+    "WMFCDMProxyCallback.cpp",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul"
diff --git a/dom/media/eme/moz.build b/dom/media/eme/moz.build
new file mode 100644
index 0000000000..76059a2790
--- /dev/null
+++ b/dom/media/eme/moz.build
@@ -0,0 +1,54 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+EXPORTS.mozilla.dom += [
+    "KeySystemNames.h",
+    "MediaEncryptedEvent.h",
+    "MediaKeyError.h",
+    "MediaKeyMessageEvent.h",
+    "MediaKeys.h",
+    "MediaKeySession.h",
+    "MediaKeyStatusMap.h",
+    "MediaKeySystemAccess.h",
+    "MediaKeySystemAccessManager.h",
+    "MediaKeySystemAccessPermissionRequest.h",
+]
+
+EXPORTS.mozilla += [
+    "CDMCaps.h",
+    "CDMProxy.h",
+    "DecryptorProxyCallback.h",
+    "DetailedPromise.h",
+    "EMEUtils.h",
+    "KeySystemConfig.h",
+]
+
+UNIFIED_SOURCES += [
+    "CDMCaps.cpp",
+    "DetailedPromise.cpp",
+    "EMEUtils.cpp",
+    "KeySystemConfig.cpp",
+    "MediaEncryptedEvent.cpp",
+    "MediaKeyError.cpp",
+    "MediaKeyMessageEvent.cpp",
+    "MediaKeys.cpp",
+    "MediaKeySession.cpp",
+    "MediaKeyStatusMap.cpp",
+    "MediaKeySystemAccess.cpp",
+    "MediaKeySystemAccessManager.cpp",
+    "MediaKeySystemAccessPermissionRequest.cpp",
+]
+
+if CONFIG["MOZ_WIDGET_TOOLKIT"] == "android":
+    DIRS += ["mediadrm"]
+    LOCAL_INCLUDES += ["/dom/media/platforms/android"]
+
+if CONFIG["MOZ_WMF_CDM"]:
+    DIRS += ["mediafoundation"]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul"