diff --git a/dom/animation/KeyframeUtils.cpp b/dom/animation/KeyframeUtils.cpp
index 6b60479bad5e..f48607e0d809 100644
--- a/dom/animation/KeyframeUtils.cpp
+++ b/dom/animation/KeyframeUtils.cpp
@@ -62,9 +62,9 @@ enum class ListAllowance { eDisallow, eAllow };
  * mValues.
  */
 struct PropertyValuesPair {
-  PropertyValuesPair() : mProperty(eCSSProperty_UNKNOWN) {}
+  PropertyValuesPair() = default;
 
-  CSSPropertyId mProperty;
+  CSSPropertyId mProperty{eCSSProperty_UNKNOWN};
   nsTArray<nsCString> mValues;
 };
 
diff --git a/dom/audiochannel/AudioChannelService.cpp b/dom/audiochannel/AudioChannelService.cpp
index 4c5db66e20ca..09355c5ec0b0 100644
--- a/dom/audiochannel/AudioChannelService.cpp
+++ b/dom/audiochannel/AudioChannelService.cpp
@@ -162,8 +162,6 @@ AudioChannelService::AudioChannelService() {
   }
 }
 
-AudioChannelService::~AudioChannelService() = default;
-
 void AudioChannelService::RegisterAudioChannelAgent(AudioChannelAgent* aAgent,
                                                     AudibleState aAudible) {
   MOZ_ASSERT(aAgent);
diff --git a/dom/audiochannel/AudioChannelService.h b/dom/audiochannel/AudioChannelService.h
index 5860a1a0d1bd..b379a7e0c73d 100644
--- a/dom/audiochannel/AudioChannelService.h
+++ b/dom/audiochannel/AudioChannelService.h
@@ -156,7 +156,7 @@ class AudioChannelService final : public nsIObserver {
 
  private:
   AudioChannelService();
-  ~AudioChannelService();
+  ~AudioChannelService() = default;
 
   void RefreshAgents(nsPIDOMWindowOuter* aWindow,
                      const std::function<void(AudioChannelAgent*)>& aFunc);
diff --git a/dom/base/Navigator.cpp b/dom/base/Navigator.cpp
index 28d4463e29b0..9b2e705cdfec 100644
--- a/dom/base/Navigator.cpp
+++ b/dom/base/Navigator.cpp
@@ -1175,7 +1175,7 @@ class BeaconStreamListener final : public nsIStreamListener {
   ~BeaconStreamListener() = default;
 
  public:
-  BeaconStreamListener() : mLoadGroup(nullptr) {}
+  BeaconStreamListener() = default;
 
   void SetLoadGroup(nsILoadGroup* aLoadGroup) { mLoadGroup = aLoadGroup; }
 
@@ -1184,7 +1184,7 @@ class BeaconStreamListener final : public nsIStreamListener {
   NS_DECL_NSIREQUESTOBSERVER
 
  private:
-  nsCOMPtr<nsILoadGroup> mLoadGroup;
+  nsCOMPtr<nsILoadGroup> mLoadGroup{};
 };
 
 NS_IMPL_ISUPPORTS(BeaconStreamListener, nsIStreamListener, nsIRequestObserver)
diff --git a/dom/cache/Action.cpp b/dom/cache/Action.cpp
index 97dc23cb7cf9..9df8df2a9dae 100644
--- a/dom/cache/Action.cpp
+++ b/dom/cache/Action.cpp
@@ -14,10 +14,6 @@ void Action::CancelOnInitiatingThread() {
   mCanceled = true;
 }
 
-Action::Action() : mCanceled(false) {}
-
-Action::~Action() = default;
-
 bool Action::IsCanceled() const { return mCanceled; }
 
 }  // namespace mozilla::dom::cache
diff --git a/dom/cache/Action.h b/dom/cache/Action.h
index d3d13e2c7aa9..6012c9bc280e 100644
--- a/dom/cache/Action.h
+++ b/dom/cache/Action.h
@@ -45,7 +45,7 @@ class Action : public SafeRefCounted<Action> {
   };
 
   // virtual because deleted through base class pointer
-  virtual ~Action();
+  virtual ~Action() = default;
 
   // Execute operations on the target thread.  Once complete call
   // Resolver::Resolve().  This can be done sync or async.
@@ -85,7 +85,7 @@ class Action : public SafeRefCounted<Action> {
   MOZ_DECLARE_REFCOUNTED_TYPENAME(cache::Action)
 
  protected:
-  Action();
+  Action() = default;
 
   // Check if this Action has been canceled.  May be called from any thread,
   // but typically used from the target thread.
@@ -93,7 +93,7 @@ class Action : public SafeRefCounted<Action> {
 
  private:
   // Accessible from any thread.
-  Atomic<bool> mCanceled;
+  Atomic<bool> mCanceled{false};
 };
 
 }  // namespace mozilla::dom::cache
diff --git a/dom/clients/manager/ClientState.cpp b/dom/clients/manager/ClientState.cpp
index b25411211a82..2552ca4ba74f 100644
--- a/dom/clients/manager/ClientState.cpp
+++ b/dom/clients/manager/ClientState.cpp
@@ -38,8 +38,6 @@ ClientWindowState& ClientWindowState::operator=(ClientWindowState&& aRight) {
   return *this;
 }
 
-ClientWindowState::~ClientWindowState() = default;
-
 mozilla::dom::VisibilityState ClientWindowState::VisibilityState() const {
   return mData->visibilityState();
 }
@@ -82,8 +80,6 @@ ClientWorkerState& ClientWorkerState::operator=(ClientWorkerState&& aRight) {
   return *this;
 }
 
-ClientWorkerState::~ClientWorkerState() = default;
-
 StorageAccess ClientWorkerState::GetStorageAccess() const {
   return mData->storageAccess();
 }
diff --git a/dom/clients/manager/ClientState.h b/dom/clients/manager/ClientState.h
index 3d601e52bbf0..2aa4f5ab5b41 100644
--- a/dom/clients/manager/ClientState.h
+++ b/dom/clients/manager/ClientState.h
@@ -50,7 +50,7 @@ class ClientWindowState final {
 
   ClientWindowState& operator=(ClientWindowState&& aRight);
 
-  ~ClientWindowState();
+  ~ClientWindowState() = default;
 
   mozilla::dom::VisibilityState VisibilityState() const;
 
@@ -84,7 +84,7 @@ class ClientWorkerState final {
 
   ClientWorkerState& operator=(ClientWorkerState&& aRight);
 
-  ~ClientWorkerState();
+  ~ClientWorkerState() = default;
 
   StorageAccess GetStorageAccess() const;
 
diff --git a/dom/commandhandler/nsControllerCommandTable.cpp b/dom/commandhandler/nsControllerCommandTable.cpp
index 7c5e09c1b4d6..94e595140695 100644
--- a/dom/commandhandler/nsControllerCommandTable.cpp
+++ b/dom/commandhandler/nsControllerCommandTable.cpp
@@ -14,14 +14,6 @@
 
 using mozilla::ControllerCommand;
 
-// this value is used to size the hash table. Just a sensible upper bound
-#define NUM_COMMANDS_LENGTH 32
-
-nsControllerCommandTable::nsControllerCommandTable()
-    : mCommandsTable(NUM_COMMANDS_LENGTH) {}
-
-nsControllerCommandTable::~nsControllerCommandTable() = default;
-
 void nsControllerCommandTable::RegisterCommand(const nsACString& aName,
                                                ControllerCommand* aCommand) {
   MOZ_DIAGNOSTIC_ASSERT(mMutable);
diff --git a/dom/commandhandler/nsControllerCommandTable.h b/dom/commandhandler/nsControllerCommandTable.h
index 25eeac36f1db..a1320e392e94 100644
--- a/dom/commandhandler/nsControllerCommandTable.h
+++ b/dom/commandhandler/nsControllerCommandTable.h
@@ -17,7 +17,7 @@ class nsICommandParams;
 
 class nsControllerCommandTable final {
  public:
-  nsControllerCommandTable();
+  nsControllerCommandTable() = default;
 
   NS_INLINE_DECL_REFCOUNTING(nsControllerCommandTable);
 
@@ -38,10 +38,12 @@ class nsControllerCommandTable final {
   void GetSupportedCommands(nsTArray<nsCString>&) const;
 
  private:
-  ~nsControllerCommandTable();
+  ~nsControllerCommandTable() = default;
+  // This value is used to size the hash table. Just a sensible upper bound
+  static constexpr size_t num_commands_length = 32;
   // Hash table of nsIControllerCommands, keyed by command name.
   nsRefPtrHashtable<nsCStringHashKey, mozilla::ControllerCommand>
-      mCommandsTable;
+      mCommandsTable{num_commands_length};
 
   // Are we mutable?
   bool mMutable = true;
diff --git a/dom/console/ConsoleReportCollector.cpp b/dom/console/ConsoleReportCollector.cpp
index 2a2db2a2baa7..f178a42f6407 100644
--- a/dom/console/ConsoleReportCollector.cpp
+++ b/dom/console/ConsoleReportCollector.cpp
@@ -16,9 +16,6 @@ using mozilla::dom::ConsoleUtils;
 
 NS_IMPL_ISUPPORTS(ConsoleReportCollector, nsIConsoleReportCollector)
 
-ConsoleReportCollector::ConsoleReportCollector()
-    : mMutex("mozilla::ConsoleReportCollector") {}
-
 void ConsoleReportCollector::AddConsoleReport(
     uint32_t aErrorFlags, const nsACString& aCategory,
     PropertiesFile aPropertiesFile, const nsACString& aSourceFileURI,
diff --git a/dom/console/ConsoleReportCollector.h b/dom/console/ConsoleReportCollector.h
index b2e43b62a67d..c4ed4ff684e5 100644
--- a/dom/console/ConsoleReportCollector.h
+++ b/dom/console/ConsoleReportCollector.h
@@ -17,7 +17,7 @@ class ConsoleReportCollected;
 
 class ConsoleReportCollector final : public nsIConsoleReportCollector {
  public:
-  ConsoleReportCollector();
+  ConsoleReportCollector() = default;
 
   void AddConsoleReport(uint32_t aErrorFlags, const nsACString& aCategory,
                         PropertiesFile aPropertiesFile,
@@ -76,7 +76,7 @@ class ConsoleReportCollector final : public nsIConsoleReportCollector {
     const CopyableTArray<nsString> mStringParams;
   };
 
-  Mutex mMutex;
+  Mutex mMutex{"mozilla::ConsoleReportCollector"};
 
   // protected by mMutex
   nsTArray<PendingReport> mPendingReports MOZ_GUARDED_BY(mMutex);
diff --git a/dom/gamepad/windows/WindowsGamepad.cpp b/dom/gamepad/windows/WindowsGamepad.cpp
index 524db5269e68..0c8a384b7cf9 100644
--- a/dom/gamepad/windows/WindowsGamepad.cpp
+++ b/dom/gamepad/windows/WindowsGamepad.cpp
@@ -149,7 +149,7 @@ class Gamepad {
   }
 
  private:
-  Gamepad() {}
+  Gamepad() = default;
 };
 
 // Drop this in favor of decltype when we require a new enough SDK.
@@ -1174,7 +1174,7 @@ class StartWindowsGamepadServiceRunnable final : public Runnable {
   }
 
  private:
-  ~StartWindowsGamepadServiceRunnable() {}
+  ~StartWindowsGamepadServiceRunnable() = default;
 };
 
 class StopWindowsGamepadServiceRunnable final : public Runnable {
@@ -1198,7 +1198,7 @@ class StopWindowsGamepadServiceRunnable final : public Runnable {
   }
 
  private:
-  ~StopWindowsGamepadServiceRunnable() {}
+  ~StopWindowsGamepadServiceRunnable() = default;
 };
 
 }  // namespace
diff --git a/dom/ipc/PreallocatedProcessManager.cpp b/dom/ipc/PreallocatedProcessManager.cpp
index 36c854222207..e896a1d80f01 100644
--- a/dom/ipc/PreallocatedProcessManager.cpp
+++ b/dom/ipc/PreallocatedProcessManager.cpp
@@ -53,7 +53,7 @@ class PreallocatedProcessManagerImpl final : public nsIObserver {
   static StaticRefPtr<PreallocatedProcessManagerImpl> sSingleton;
 
   PreallocatedProcessManagerImpl();
-  ~PreallocatedProcessManagerImpl();
+  ~PreallocatedProcessManagerImpl() = default;
 
   void Init();
 
@@ -115,7 +115,6 @@ PreallocatedProcessManagerImpl::PreallocatedProcessManagerImpl()
 // Note: mPreallocatedProcesses may not be null, but all processes should
 // be dead (IsDead==true).  We block Erase() when our observer sees
 // shutdown starting.
-PreallocatedProcessManagerImpl::~PreallocatedProcessManagerImpl() = default;
 
 void PreallocatedProcessManagerImpl::Init() {
   Preferences::AddStrongObserver(this, "dom.ipc.processPrelaunch.enabled");
diff --git a/dom/ipc/RefMessageBodyService.cpp b/dom/ipc/RefMessageBodyService.cpp
index b04f2c87f32e..7524005d71e7 100644
--- a/dom/ipc/RefMessageBodyService.cpp
+++ b/dom/ipc/RefMessageBodyService.cpp
@@ -63,8 +63,6 @@ MozExternalRefCountType RefMessageBodyService::Release() {
   return 0;
 }
 
-RefMessageBodyService::~RefMessageBodyService() = default;
-
 const nsID RefMessageBodyService::Register(
     already_AddRefed<RefMessageBody> aBody, ErrorResult& aRv) {
   RefPtr<RefMessageBody> body = aBody;
diff --git a/dom/ipc/RefMessageBodyService.h b/dom/ipc/RefMessageBodyService.h
index d68e54a63ff4..7df304333d2a 100644
--- a/dom/ipc/RefMessageBodyService.h
+++ b/dom/ipc/RefMessageBodyService.h
@@ -122,7 +122,7 @@ class RefMessageBodyService final {
 
  private:
   explicit RefMessageBodyService(const StaticMutexAutoLock& aProofOfLock);
-  ~RefMessageBodyService();
+  ~RefMessageBodyService() = default;
 
  protected:
   ::mozilla::ThreadSafeAutoRefCnt mRefCnt;
diff --git a/dom/media/CallbackThreadRegistry.cpp b/dom/media/CallbackThreadRegistry.cpp
index bf229aa44d35..3b2455c53ed1 100644
--- a/dom/media/CallbackThreadRegistry.cpp
+++ b/dom/media/CallbackThreadRegistry.cpp
@@ -22,9 +22,6 @@ struct CallbackThreadRegistrySingleton {
   UniquePtr<CallbackThreadRegistry> mRegistry;
 };
 
-CallbackThreadRegistry::CallbackThreadRegistry()
-    : mThreadIds("CallbackThreadRegistry::mThreadIds") {}
-
 /* static */
 CallbackThreadRegistry* CallbackThreadRegistry::Get() {
   static CallbackThreadRegistrySingleton sSingleton;
diff --git a/dom/media/CallbackThreadRegistry.h b/dom/media/CallbackThreadRegistry.h
index ff07accad5fd..0ec822fd653f 100644
--- a/dom/media/CallbackThreadRegistry.h
+++ b/dom/media/CallbackThreadRegistry.h
@@ -19,7 +19,7 @@ namespace mozilla {
 // path.
 class CallbackThreadRegistry final {
  public:
-  CallbackThreadRegistry();
+  CallbackThreadRegistry() = default;
 
   // It would be nice to be able to assert that all threads have been
   // unregistered, but we can't: it's legal to suspend an audio stream, so
@@ -47,7 +47,8 @@ class CallbackThreadRegistry final {
     ProfilerThreadId mId;  // from profiler_current_thread_id
     int mUserCount = 0;
   };
-  DataMutex<nsTArray<ThreadUserCount>> mThreadIds;
+  DataMutex<nsTArray<ThreadUserCount>> mThreadIds{
+      "CallbackThreadRegistry::mThreadIds"};
 };
 
 }  // namespace mozilla
diff --git a/dom/media/GraphDriver.h b/dom/media/GraphDriver.h
index a9809c901992..d4f06b9f86db 100644
--- a/dom/media/GraphDriver.h
+++ b/dom/media/GraphDriver.h
@@ -116,7 +116,8 @@ struct GraphInterface : public nsISupports {
         mSwitchedRunnable = nullptr;
       }
     };
-    Variant<Undefined, StillProcessing, Stop, SwitchDriver> mResult;
+    Variant<Undefined, StillProcessing, Stop, SwitchDriver> mResult{
+        Undefined()};
 
     explicit IterationResult(StillProcessing&& aArg)
         : mResult(std::move(aArg)) {}
@@ -124,7 +125,7 @@ struct GraphInterface : public nsISupports {
     explicit IterationResult(SwitchDriver&& aArg) : mResult(std::move(aArg)) {}
 
    public:
-    IterationResult() : mResult(Undefined()) {}
+    IterationResult() = default;
     IterationResult(const IterationResult&) = delete;
     IterationResult(IterationResult&&) = default;
 
@@ -393,7 +394,7 @@ class MediaTrackGraphInitThreadRunnable;
  */
 class ThreadedDriver : public GraphDriver {
   class IterationWaitHelper {
-    Monitor mMonitor MOZ_UNANNOTATED;
+    Monitor mMonitor MOZ_UNANNOTATED{"IterationWaitHelper::mMonitor"};
     // The below members are guarded by mMonitor.
 
     // Whether another iteration is required either to process control
@@ -404,7 +405,7 @@ class ThreadedDriver : public GraphDriver {
     TimeStamp mWakeTime;
 
    public:
-    IterationWaitHelper() : mMonitor("IterationWaitHelper::mMonitor") {}
+    IterationWaitHelper() = default;
 
     /**
      * If another iteration is needed we wait for aDuration, otherwise we wait
diff --git a/dom/media/VideoSegment.cpp b/dom/media/VideoSegment.cpp
index 062006f790ac..415731c6e0aa 100644
--- a/dom/media/VideoSegment.cpp
+++ b/dom/media/VideoSegment.cpp
@@ -190,6 +190,4 @@ VideoSegment::VideoSegment()
 VideoSegment::VideoSegment(VideoSegment&& aSegment)
     : MediaSegmentBase<VideoSegment, VideoChunk>(std::move(aSegment)) {}
 
-VideoSegment::~VideoSegment() = default;
-
 }  // namespace mozilla
diff --git a/dom/media/VideoSegment.h b/dom/media/VideoSegment.h
index 3c63623c2c8c..018f49c8753f 100644
--- a/dom/media/VideoSegment.h
+++ b/dom/media/VideoSegment.h
@@ -116,7 +116,7 @@ class VideoSegment : public MediaSegmentBase<VideoSegment, VideoChunk> {
   VideoSegment(const VideoSegment&) = delete;
   VideoSegment& operator=(const VideoSegment&) = delete;
 
-  ~VideoSegment();
+  ~VideoSegment() = default;
 
   void AppendFrame(const VideoChunk& aChunk,
                    const Maybe<bool>& aForceBlack = Nothing(),
diff --git a/dom/media/eme/mediafoundation/WMFCDMProxy.cpp b/dom/media/eme/mediafoundation/WMFCDMProxy.cpp
index e4e04978483f..9d41dfc9ea64 100644
--- a/dom/media/eme/mediafoundation/WMFCDMProxy.cpp
+++ b/dom/media/eme/mediafoundation/WMFCDMProxy.cpp
@@ -60,7 +60,7 @@ WMFCDMProxy::WMFCDMProxy(dom::MediaKeys* aKeys, const nsAString& aKeySystem,
   MOZ_ASSERT(NS_IsMainThread());
 }
 
-WMFCDMProxy::~WMFCDMProxy() {}
+WMFCDMProxy::~WMFCDMProxy() = default;
 
 void WMFCDMProxy::Init(PromiseId aPromiseId, const nsAString& aOrigin,
                        const nsAString& aTopLevelOrigin,
diff --git a/dom/media/mediaelement/TimeRanges.cpp b/dom/media/mediaelement/TimeRanges.cpp
index f1bc5f102834..3daa65076944 100644
--- a/dom/media/mediaelement/TimeRanges.cpp
+++ b/dom/media/mediaelement/TimeRanges.cpp
@@ -19,8 +19,6 @@ NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TimeRanges)
   NS_INTERFACE_MAP_ENTRY(nsISupports)
 NS_INTERFACE_MAP_END
 
-TimeRanges::TimeRanges() : mParent(nullptr) {}
-
 TimeRanges::TimeRanges(nsISupports* aParent) : mParent(aParent) {}
 
 TimeRanges::TimeRanges(nsISupports* aParent,
diff --git a/dom/media/mediaelement/TimeRanges.h b/dom/media/mediaelement/TimeRanges.h
index 6af6106fbe58..6f949e8a7f8c 100644
--- a/dom/media/mediaelement/TimeRanges.h
+++ b/dom/media/mediaelement/TimeRanges.h
@@ -27,7 +27,7 @@ class TimeRanges final : public nsISupports, public nsWrapperCache {
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS_FINAL
   NS_DECL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(TimeRanges)
 
-  TimeRanges();
+  TimeRanges() = default;
   explicit TimeRanges(nsISupports* aParent);
   explicit TimeRanges(const media::TimeIntervals& aTimeIntervals);
   explicit TimeRanges(const media::TimeRanges& aTimeRanges);
diff --git a/dom/media/mediasink/AudioDecoderInputTrack.h b/dom/media/mediasink/AudioDecoderInputTrack.h
index 99b733c70906..45f87ff23b1a 100644
--- a/dom/media/mediasink/AudioDecoderInputTrack.h
+++ b/dom/media/mediasink/AudioDecoderInputTrack.h
@@ -50,9 +50,7 @@ class AudioDecoderInputTrack final : public ProcessedMediaTrack {
     struct Empty {};
     struct ClearFutureData {};
     struct DecodedData {
-      DecodedData()
-          : mStartTime(media::TimeUnit::Invalid()),
-            mEndTime(media::TimeUnit::Invalid()) {}
+      DecodedData() = default;
       DecodedData(DecodedData&& aDecodedData)
           : mSegment(std::move(aDecodedData.mSegment)) {
         mStartTime = aDecodedData.mStartTime;
@@ -69,12 +67,12 @@ class AudioDecoderInputTrack final : public ProcessedMediaTrack {
         mEndTime = media::TimeUnit::Invalid();
       }
       AudioSegment mSegment;
-      media::TimeUnit mStartTime;
-      media::TimeUnit mEndTime;
+      media::TimeUnit mStartTime{media::TimeUnit::Invalid()};
+      media::TimeUnit mEndTime{media::TimeUnit::Invalid()};
     };
     struct EOS {};
 
-    SPSCData() : mData(Empty()) {};
+    SPSCData() = default;
     explicit SPSCData(ClearFutureData&& aArg) : mData(std::move(aArg)) {};
     explicit SPSCData(DecodedData&& aArg) : mData(std::move(aArg)) {};
     explicit SPSCData(EOS&& aArg) : mData(std::move(aArg)) {};
@@ -88,7 +86,7 @@ class AudioDecoderInputTrack final : public ProcessedMediaTrack {
       return IsDecodedData() ? &mData.as<DecodedData>() : nullptr;
     }
 
-    Variant<Empty, ClearFutureData, DecodedData, EOS> mData;
+    Variant<Empty, ClearFutureData, DecodedData, EOS> mData{Empty()};
   };
 
   // Decoder thread API
diff --git a/dom/media/ogg/OggCodecStore.cpp b/dom/media/ogg/OggCodecStore.cpp
index fad9e65d5eca..aa69fca7743b 100644
--- a/dom/media/ogg/OggCodecStore.cpp
+++ b/dom/media/ogg/OggCodecStore.cpp
@@ -6,8 +6,6 @@
 
 namespace mozilla {
 
-OggCodecStore::OggCodecStore() : mMonitor("CodecStore") {}
-
 OggCodecState* OggCodecStore::Add(uint32_t serial,
                                   UniquePtr<OggCodecState> codecState) {
   MonitorAutoLock mon(mMonitor);
diff --git a/dom/media/ogg/OggCodecStore.h b/dom/media/ogg/OggCodecStore.h
index e671feab3a8d..c81b5d6c060b 100644
--- a/dom/media/ogg/OggCodecStore.h
+++ b/dom/media/ogg/OggCodecStore.h
@@ -16,7 +16,7 @@ namespace mozilla {
 // streams.
 class OggCodecStore {
  public:
-  OggCodecStore();
+  OggCodecStore() = default;
   OggCodecState* Add(uint32_t serial, UniquePtr<OggCodecState> codecState);
   bool Contains(uint32_t serial);
   OggCodecState* Get(uint32_t serial);
@@ -27,7 +27,7 @@ class OggCodecStore {
   nsClassHashtable<nsUint32HashKey, OggCodecState> mCodecStates;
 
   // Protects the |mCodecStates| and the |mKnownStreams| members.
-  Monitor mMonitor MOZ_UNANNOTATED;
+  Monitor mMonitor MOZ_UNANNOTATED{"CodecStore"};
 };
 
 }  // namespace mozilla
diff --git a/dom/media/platforms/omx/OmxPlatformLayer.cpp b/dom/media/platforms/omx/OmxPlatformLayer.cpp
index 287b8fb98d85..432a9ad5c5ea 100644
--- a/dom/media/platforms/omx/OmxPlatformLayer.cpp
+++ b/dom/media/platforms/omx/OmxPlatformLayer.cpp
@@ -185,7 +185,7 @@ UniquePtr<OmxAudioConfig> ConfigForMime(const nsACString& aMimeType) {
 
 class OmxCommonVideoConfig : public OmxVideoConfig {
  public:
-  explicit OmxCommonVideoConfig() : OmxVideoConfig() {}
+  explicit OmxCommonVideoConfig() = default;
 
   OMX_ERRORTYPE Apply(OmxPlatformLayer& aOmx, const VideoInfo& aInfo) override {
     OMX_ERRORTYPE err = OMX_ErrorNone;
diff --git a/dom/media/platforms/wmf/DXVA2Manager.cpp b/dom/media/platforms/wmf/DXVA2Manager.cpp
index cc39e9779213..9d5d8dffc783 100644
--- a/dom/media/platforms/wmf/DXVA2Manager.cpp
+++ b/dom/media/platforms/wmf/DXVA2Manager.cpp
@@ -326,7 +326,7 @@ static Atomic<uint32_t> sDXVAVideosCount(0);
 class D3D11DXVA2Manager : public DXVA2Manager {
  public:
   D3D11DXVA2Manager();
-  virtual ~D3D11DXVA2Manager();
+  virtual ~D3D11DXVA2Manager() = default;
 
   HRESULT Init(layers::KnowsCompositor* aKnowsCompositor,
                nsACString& aFailureReason, ID3D11Device* aDevice);
@@ -609,8 +609,6 @@ bool D3D11DXVA2Manager::SupportsConfig(const VideoInfo& aInfo,
 D3D11DXVA2Manager::D3D11DXVA2Manager()
     : mZeroCopyUsageInfo(new layers::ZeroCopyUsageInfo) {}
 
-D3D11DXVA2Manager::~D3D11DXVA2Manager() {}
-
 IUnknown* D3D11DXVA2Manager::GetDXVADeviceManager() {
   MutexAutoLock lock(mLock);
   return mDXGIDeviceManager;
diff --git a/dom/media/platforms/wmf/WMFMediaDataDecoder.cpp b/dom/media/platforms/wmf/WMFMediaDataDecoder.cpp
index 57830107e46f..c918b1d8dcde 100644
--- a/dom/media/platforms/wmf/WMFMediaDataDecoder.cpp
+++ b/dom/media/platforms/wmf/WMFMediaDataDecoder.cpp
@@ -22,8 +22,6 @@ WMFMediaDataDecoder::WMFMediaDataDecoder(MFTManager* aMFTManager)
           "WMFMediaDataDecoder")),
       mMFTManager(aMFTManager) {}
 
-WMFMediaDataDecoder::~WMFMediaDataDecoder() {}
-
 RefPtr<MediaDataDecoder::InitPromise> WMFMediaDataDecoder::Init() {
   MOZ_ASSERT(!mIsShutDown);
   return InitPromise::CreateAndResolve(mMFTManager->GetType(), __func__);
diff --git a/dom/media/platforms/wmf/WMFMediaDataDecoder.h b/dom/media/platforms/wmf/WMFMediaDataDecoder.h
index a96d6fb3fb34..48c9bbc10359 100644
--- a/dom/media/platforms/wmf/WMFMediaDataDecoder.h
+++ b/dom/media/platforms/wmf/WMFMediaDataDecoder.h
@@ -19,7 +19,7 @@ namespace mozilla {
 // by the MFT into a MediaData object.
 class MFTManager {
  public:
-  virtual ~MFTManager() {}
+  virtual ~MFTManager() = default;
 
   // Submit a compressed sample for decoding.
   // This should forward to the MFTDecoder after performing
@@ -126,7 +126,7 @@ class WMFMediaDataDecoder final
   virtual void SetSeekThreshold(const media::TimeUnit& aTime) override;
 
  private:
-  ~WMFMediaDataDecoder();
+  ~WMFMediaDataDecoder() = default;
 
   RefPtr<DecodePromise> ProcessError(HRESULT aError, const char* aReason);
 
diff --git a/dom/media/systemservices/MediaSystemResourceService.cpp b/dom/media/systemservices/MediaSystemResourceService.cpp
index d54feafc6536..dfa72f6f24ed 100644
--- a/dom/media/systemservices/MediaSystemResourceService.cpp
+++ b/dom/media/systemservices/MediaSystemResourceService.cpp
@@ -42,8 +42,6 @@ MediaSystemResourceService::MediaSystemResourceService() : mDestroyed(false) {
   MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
 }
 
-MediaSystemResourceService::~MediaSystemResourceService() = default;
-
 void MediaSystemResourceService::Destroy() { mDestroyed = true; }
 
 void MediaSystemResourceService::Acquire(
diff --git a/dom/media/systemservices/MediaSystemResourceService.h b/dom/media/systemservices/MediaSystemResourceService.h
index 8f4b7c777f2c..60e20199b776 100644
--- a/dom/media/systemservices/MediaSystemResourceService.h
+++ b/dom/media/systemservices/MediaSystemResourceService.h
@@ -38,7 +38,7 @@ class MediaSystemResourceService {
 
  private:
   MediaSystemResourceService();
-  ~MediaSystemResourceService();
+  ~MediaSystemResourceService() = default;
 
   struct MediaSystemResourceRequest {
     MediaSystemResourceRequest() : mParent(nullptr), mId(-1) {}
diff --git a/dom/media/webrtc/jsapi/MediaTransportHandler.h b/dom/media/webrtc/jsapi/MediaTransportHandler.h
index 899e83d94f64..b8bbe110b7bf 100644
--- a/dom/media/webrtc/jsapi/MediaTransportHandler.h
+++ b/dom/media/webrtc/jsapi/MediaTransportHandler.h
@@ -44,8 +44,7 @@ class MediaTransportHandler {
   // as appropriate.
   static already_AddRefed<MediaTransportHandler> Create();
 
-  explicit MediaTransportHandler()
-      : mStateCacheMutex("MediaTransportHandler::mStateCacheMutex") {}
+  explicit MediaTransportHandler() = default;
 
   typedef MozPromise<dom::Sequence<nsString>, nsresult, true> IceLogPromise;
 
@@ -186,7 +185,7 @@ class MediaTransportHandler {
                          Maybe<dom::RTCErrorParams> aError = Nothing());
   virtual void Destroy() = 0;
   virtual ~MediaTransportHandler() = default;
-  mutable Mutex mStateCacheMutex;
+  mutable Mutex mStateCacheMutex{"MediaTransportHandler::mStateCacheMutex"};
   std::map<std::string, TransportLayer::State> mStateCache;
   std::map<std::string, TransportLayer::State> mRtcpStateCache;
 
diff --git a/dom/media/webrtc/sdp/RsdparsaSdp.h b/dom/media/webrtc/sdp/RsdparsaSdp.h
index 0c906a031e11..a9d295d4cf28 100644
--- a/dom/media/webrtc/sdp/RsdparsaSdp.h
+++ b/dom/media/webrtc/sdp/RsdparsaSdp.h
@@ -54,11 +54,11 @@ class RsdparsaSdp final : public Sdp {
   void Serialize(std::ostream&) const override;
 
  private:
-  RsdparsaSdp() : mOrigin("", 0, 0, sdp::kIPv4, "") {}
+  RsdparsaSdp() = default;
   RsdparsaSdp(const RsdparsaSdp& aOrig);
 
   RsdparsaSessionHandle mSession;
-  SdpOrigin mOrigin;
+  SdpOrigin mOrigin{"", 0, 0, sdp::kIPv4, ""};
   UniquePtr<RsdparsaSdpAttributeList> mAttributeList;
   std::vector<UniquePtr<RsdparsaSdpMediaSection>> mMediaSections;
 };
diff --git a/dom/media/webrtc/sdp/SipccSdp.h b/dom/media/webrtc/sdp/SipccSdp.h
index 20e2b4fbc1da..c6b32d6f0289 100644
--- a/dom/media/webrtc/sdp/SipccSdp.h
+++ b/dom/media/webrtc/sdp/SipccSdp.h
@@ -62,14 +62,14 @@ class SipccSdp final : public Sdp {
  private:
   using InternalResults = SdpParser::InternalResults;
 
-  SipccSdp() : mOrigin("", 0, 0, sdp::kIPv4, ""), mAttributeList(nullptr) {}
+  SipccSdp() = default;
 
   bool Load(sdp_t* sdp, InternalResults& results);
   bool LoadOrigin(sdp_t* sdp, InternalResults& results);
 
-  SdpOrigin mOrigin;
+  SdpOrigin mOrigin{"", 0, 0, sdp::kIPv4, ""};
   SipccSdpBandwidths mBandwidths;
-  SipccSdpAttributeList mAttributeList;
+  SipccSdpAttributeList mAttributeList{nullptr};
   std::vector<UniquePtr<SipccSdpMediaSection>> mMediaSections;
 };
 
diff --git a/dom/media/webspeech/synth/windows/SapiService.cpp b/dom/media/webspeech/synth/windows/SapiService.cpp
index 35f8cc3674d2..fbab9749db84 100644
--- a/dom/media/webspeech/synth/windows/SapiService.cpp
+++ b/dom/media/webspeech/synth/windows/SapiService.cpp
@@ -46,7 +46,7 @@ class SapiCallback final : public nsISpeechTaskCallback {
   void OnSpeechEvent(const SPEVENT& speechEvent);
 
  private:
-  ~SapiCallback() {}
+  ~SapiCallback() = default;
 
   float GetTimeDurationFromStart() const {
     TimeDuration duration = TimeStamp::Now() - mStartingTime;
@@ -189,7 +189,7 @@ NS_IMPL_RELEASE(SapiService)
 
 SapiService::SapiService() : mInitialized(false) {}
 
-SapiService::~SapiService() {}
+SapiService::~SapiService() = default;
 
 bool SapiService::Init() {
   AUTO_PROFILER_LABEL("SapiService::Init", OTHER);
diff --git a/dom/midi/MIDIMessageQueue.cpp b/dom/midi/MIDIMessageQueue.cpp
index 9a7cc145a136..d578553db318 100644
--- a/dom/midi/MIDIMessageQueue.cpp
+++ b/dom/midi/MIDIMessageQueue.cpp
@@ -8,8 +8,6 @@
 
 namespace mozilla::dom {
 
-MIDIMessageQueue::MIDIMessageQueue() : mMutex("MIDIMessageQueue::mMutex") {}
-
 class MIDIMessageTimestampComparator {
  public:
   bool Equals(const MIDIMessage& a, const MIDIMessage& b) const {
diff --git a/dom/midi/MIDIMessageQueue.h b/dom/midi/MIDIMessageQueue.h
index f314f9ab507f..bb6036189cb4 100644
--- a/dom/midi/MIDIMessageQueue.h
+++ b/dom/midi/MIDIMessageQueue.h
@@ -27,7 +27,7 @@ class MIDIMessage;
  */
 class MIDIMessageQueue {
  public:
-  MIDIMessageQueue();
+  MIDIMessageQueue() = default;
   ~MIDIMessageQueue() = default;
   // Adds an array of possibly out-of-order messages to our queue.
   void Add(nsTArray<MIDIMessage>& aMsg);
@@ -47,7 +47,7 @@ class MIDIMessageQueue {
   // Array of messages to be sent.
   nsTArray<MIDIMessage> mMessageQueue;
   // Mutex for coordinating cross thread array access.
-  Mutex mMutex MOZ_UNANNOTATED;
+  Mutex mMutex MOZ_UNANNOTATED{"MIDIMessageQueue::mMutex"};
 };
 
 }  // namespace dom
diff --git a/dom/quota/PersistenceScope.h b/dom/quota/PersistenceScope.h
index 6c1396b30b45..402bb254cba3 100644
--- a/dom/quota/PersistenceScope.h
+++ b/dom/quota/PersistenceScope.h
@@ -35,10 +35,10 @@ class PersistenceScope {
 
   using DataType = Variant<Value, Set, Null>;
 
-  DataType mData;
+  DataType mData{Null{}};
 
  public:
-  PersistenceScope() : mData(Null()) {}
+  PersistenceScope() = default;
 
   bool operator==(const PersistenceScope& aOther) = delete;
 
diff --git a/dom/svg/SVGNumberList.h b/dom/svg/SVGNumberList.h
index 3f220d2ea46e..2902583d911c 100644
--- a/dom/svg/SVGNumberList.h
+++ b/dom/svg/SVGNumberList.h
@@ -153,7 +153,7 @@ class SVGNumberList {
  */
 class SVGNumberListAndInfo : public SVGNumberList {
  public:
-  SVGNumberListAndInfo() : mElement(nullptr) {}
+  SVGNumberListAndInfo() = default;
 
   explicit SVGNumberListAndInfo(dom::SVGElement* aElement)
       : mElement(do_GetWeakReference(static_cast<nsINode*>(aElement))) {}
@@ -192,7 +192,7 @@ class SVGNumberListAndInfo : public SVGNumberList {
   // cached baseVal SMILValue. See the comments starting at:
   // https://bugzilla.mozilla.org/show_bug.cgi?id=515116#c15
   // See also https://bugzilla.mozilla.org/show_bug.cgi?id=653497
-  nsWeakPtr mElement;
+  nsWeakPtr mElement{nullptr};
 };
 
 }  // namespace mozilla
diff --git a/dom/workers/WorkerCSPEventListener.cpp b/dom/workers/WorkerCSPEventListener.cpp
index cbbe0a63c4f0..f3ba906f63af 100644
--- a/dom/workers/WorkerCSPEventListener.cpp
+++ b/dom/workers/WorkerCSPEventListener.cpp
@@ -60,9 +60,6 @@ already_AddRefed<WorkerCSPEventListener> WorkerCSPEventListener::Create(
   return listener.forget();
 }
 
-WorkerCSPEventListener::WorkerCSPEventListener()
-    : mMutex("WorkerCSPEventListener::mMutex") {}
-
 NS_IMETHODIMP
 WorkerCSPEventListener::OnCSPViolationEvent(const nsAString& aJSON,
                                             const nsAString& aReportGroupName) {
diff --git a/dom/workers/WorkerCSPEventListener.h b/dom/workers/WorkerCSPEventListener.h
index ddb7379c89e2..a61bb72dabec 100644
--- a/dom/workers/WorkerCSPEventListener.h
+++ b/dom/workers/WorkerCSPEventListener.h
@@ -24,10 +24,10 @@ class WorkerCSPEventListener final : public nsICSPEventListener {
       WorkerPrivate* aWorkerPrivate);
 
  private:
-  WorkerCSPEventListener();
+  WorkerCSPEventListener() = default;
   ~WorkerCSPEventListener() = default;
 
-  Mutex mMutex;
+  Mutex mMutex{"WorkerCSPEventListener::mMutex"};
 
   // Protected by mutex.
   RefPtr<WeakWorkerRef> mWorkerRef MOZ_GUARDED_BY(mMutex);
diff --git a/dom/workers/WorkerDocumentListener.cpp b/dom/workers/WorkerDocumentListener.cpp
index e1bf87f3cd93..0f188cc18ea6 100644
--- a/dom/workers/WorkerDocumentListener.cpp
+++ b/dom/workers/WorkerDocumentListener.cpp
@@ -13,11 +13,6 @@
 
 namespace mozilla::dom {
 
-WorkerDocumentListener::WorkerDocumentListener()
-    : mMutex("mozilla::dom::WorkerDocumentListener::mMutex") {}
-
-WorkerDocumentListener::~WorkerDocumentListener() = default;
-
 RefPtr<WorkerDocumentListener> WorkerDocumentListener::Create(
     WorkerPrivate* aWorkerPrivate) {
   MOZ_ASSERT(aWorkerPrivate);
diff --git a/dom/workers/WorkerDocumentListener.h b/dom/workers/WorkerDocumentListener.h
index 4e8e2594f544..6b6dd89aee98 100644
--- a/dom/workers/WorkerDocumentListener.h
+++ b/dom/workers/WorkerDocumentListener.h
@@ -18,7 +18,7 @@ class WorkerDocumentListener final {
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(WorkerDocumentListener)
 
  public:
-  WorkerDocumentListener();
+  WorkerDocumentListener() = default;
 
   void OnVisible(bool aVisible);
   void SetListening(uint64_t aWindowID, bool aListen);
@@ -27,9 +27,10 @@ class WorkerDocumentListener final {
   static RefPtr<WorkerDocumentListener> Create(WorkerPrivate* aWorkerPrivate);
 
  private:
-  ~WorkerDocumentListener();
+  ~WorkerDocumentListener() = default;
 
-  Mutex mMutex MOZ_UNANNOTATED;  // protects mWorkerRef
+  Mutex mMutex MOZ_UNANNOTATED{
+      "mozilla::dom::WorkerDocumentListener::mMutex"};  // protects mWorkerRef
   RefPtr<ThreadSafeWorkerRef> mWorkerRef;
 };