diff --git a/caps/DomainPolicy.cpp b/caps/DomainPolicy.cpp
index 484be9b19b7c..11dc12f39ccf 100644
--- a/caps/DomainPolicy.cpp
+++ b/caps/DomainPolicy.cpp
@@ -31,7 +31,7 @@ static nsresult BroadcastDomainSetChange(DomainSetType aSetType,
     return NS_OK;
   }
 
-  OptionalURIParams uri;
+  Maybe<URIParams> uri;
   SerializeURI(aDomain, uri);
 
   for (uint32_t i = 0; i < parents.Length(); i++) {
diff --git a/docshell/base/nsDefaultURIFixup.cpp b/docshell/base/nsDefaultURIFixup.cpp
index ffd241b2144c..33c7a59aaa0f 100644
--- a/docshell/base/nsDefaultURIFixup.cpp
+++ b/docshell/base/nsDefaultURIFixup.cpp
@@ -410,7 +410,7 @@ nsDefaultURIFixup::KeywordToURI(const nsACString& aKeyword,
     }
 
     RefPtr<nsIInputStream> postData;
-    ipc::OptionalURIParams uri;
+    Maybe<ipc::URIParams> uri;
     nsAutoString providerName;
     if (!contentChild->SendKeywordToURI(keyword, &providerName, &postData,
                                         &uri)) {
diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index bc18ab257631..53fc6f2eda0c 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -873,7 +873,7 @@ nsresult ContentChild::ProvideWindowCommon(
       return rv;
     }
 
-    OptionalURIParams uriToLoad;
+    Maybe<URIParams> uriToLoad;
     SerializeURI(aURI, uriToLoad);
     Unused << SendCreateWindowInDifferentProcess(
         aTabOpener, aChromeFlags, aCalledFromJS, aPositionSpecified,
@@ -1073,11 +1073,9 @@ nsresult ContentChild::ProvideWindowCommon(
       return rv;
     }
 
-    OptionalURIParams uriToLoad;
+    Maybe<URIParams> uriToLoad;
     if (aURI) {
       SerializeURI(aURI, uriToLoad);
-    } else {
-      uriToLoad = mozilla::void_t();
     }
 
     SendCreateWindow(aTabOpener, newChild, aChromeFlags, aCalledFromJS,
@@ -2017,13 +2015,13 @@ bool ContentChild::DeallocPPSMContentDownloaderChild(
 }
 
 PExternalHelperAppChild* ContentChild::AllocPExternalHelperAppChild(
-    const OptionalURIParams& uri,
+    const Maybe<URIParams>& uri,
     const Maybe<mozilla::net::LoadInfoArgs>& aLoadInfoArgs,
     const nsCString& aMimeContentType, const nsCString& aContentDisposition,
     const uint32_t& aContentDispositionHint,
     const nsString& aContentDispositionFilename, const bool& aForceSave,
     const int64_t& aContentLength, const bool& aWasFileChannel,
-    const OptionalURIParams& aReferrer, PBrowserChild* aBrowser) {
+    const Maybe<URIParams>& aReferrer, PBrowserChild* aBrowser) {
   auto* child = new ExternalHelperAppChild();
   child->AddRef();
   return child;
@@ -2742,7 +2740,7 @@ bool ContentChild::DeallocPOfflineCacheUpdateChild(
 
 mozilla::ipc::IPCResult ContentChild::RecvDomainSetChanged(
     const uint32_t& aSetType, const uint32_t& aChangeType,
-    const OptionalURIParams& aDomain) {
+    const Maybe<URIParams>& aDomain) {
   if (aChangeType == ACTIVATE_POLICY) {
     if (mPolicy) {
       return IPC_OK();
diff --git a/dom/ipc/ContentChild.h b/dom/ipc/ContentChild.h
index 91cdb3202dd1..eb55d752e50f 100644
--- a/dom/ipc/ContentChild.h
+++ b/dom/ipc/ContentChild.h
@@ -62,7 +62,6 @@ nsresult GetObjDir(nsIFile** aObjDir);
 #endif /* XP_MACOSX */
 
 namespace ipc {
-class OptionalURIParams;
 class URIParams;
 }  // namespace ipc
 
@@ -85,7 +84,6 @@ class ContentChild final : public PContentChild,
                            public mozilla::ipc::IShmemAllocator {
   typedef mozilla::dom::ClonedMessageData ClonedMessageData;
   typedef mozilla::ipc::FileDescriptor FileDescriptor;
-  typedef mozilla::ipc::OptionalURIParams OptionalURIParams;
   typedef mozilla::ipc::PFileDescriptorSetChild PFileDescriptorSetChild;
   typedef mozilla::ipc::URIParams URIParams;
 
@@ -279,13 +277,13 @@ class ContentChild final : public PContentChild,
       PPSMContentDownloaderChild* aDownloader);
 
   PExternalHelperAppChild* AllocPExternalHelperAppChild(
-      const OptionalURIParams& uri,
+      const Maybe<URIParams>& uri,
       const Maybe<mozilla::net::LoadInfoArgs>& aLoadInfoArgs,
       const nsCString& aMimeContentType, const nsCString& aContentDisposition,
       const uint32_t& aContentDispositionHint,
       const nsString& aContentDispositionFilename, const bool& aForceSave,
       const int64_t& aContentLength, const bool& aWasFileChannel,
-      const OptionalURIParams& aReferrer, PBrowserChild* aBrowser);
+      const Maybe<URIParams>& aReferrer, PBrowserChild* aBrowser);
 
   bool DeallocPExternalHelperAppChild(PExternalHelperAppChild* aService);
 
@@ -450,9 +448,9 @@ class ContentChild final : public PContentChild,
 
   mozilla::ipc::IPCResult RecvUpdateWindow(const uintptr_t& aChildId);
 
-  mozilla::ipc::IPCResult RecvDomainSetChanged(
-      const uint32_t& aSetType, const uint32_t& aChangeType,
-      const OptionalURIParams& aDomain);
+  mozilla::ipc::IPCResult RecvDomainSetChanged(const uint32_t& aSetType,
+                                               const uint32_t& aChangeType,
+                                               const Maybe<URIParams>& aDomain);
 
   mozilla::ipc::IPCResult RecvShutdown();
 
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index e5bb8b74a6a0..e72f48404df3 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -3631,13 +3631,13 @@ bool ContentParent::DeallocPPSMContentDownloaderParent(
 }
 
 PExternalHelperAppParent* ContentParent::AllocPExternalHelperAppParent(
-    const OptionalURIParams& uri,
+    const Maybe<URIParams>& uri,
     const Maybe<mozilla::net::LoadInfoArgs>& aLoadInfoArgs,
     const nsCString& aMimeContentType, const nsCString& aContentDisposition,
     const uint32_t& aContentDispositionHint,
     const nsString& aContentDispositionFilename, const bool& aForceSave,
     const int64_t& aContentLength, const bool& aWasFileChannel,
-    const OptionalURIParams& aReferrer, PBrowserParent* aBrowser) {
+    const Maybe<URIParams>& aReferrer, PBrowserParent* aBrowser) {
   ExternalHelperAppParent* parent = new ExternalHelperAppParent(
       uri, aContentLength, aWasFileChannel, aContentDisposition,
       aContentDispositionHint, aContentDispositionFilename);
@@ -3654,13 +3654,13 @@ bool ContentParent::DeallocPExternalHelperAppParent(
 }
 
 mozilla::ipc::IPCResult ContentParent::RecvPExternalHelperAppConstructor(
-    PExternalHelperAppParent* actor, const OptionalURIParams& uri,
+    PExternalHelperAppParent* actor, const Maybe<URIParams>& uri,
     const Maybe<LoadInfoArgs>& loadInfoArgs, const nsCString& aMimeContentType,
     const nsCString& aContentDisposition,
     const uint32_t& aContentDispositionHint,
     const nsString& aContentDispositionFilename, const bool& aForceSave,
     const int64_t& aContentLength, const bool& aWasFileChannel,
-    const OptionalURIParams& aReferrer, PBrowserParent* aBrowser) {
+    const Maybe<URIParams>& aReferrer, PBrowserParent* aBrowser) {
   static_cast<ExternalHelperAppParent*>(actor)->Init(
       loadInfoArgs, aMimeContentType, aForceSave, aReferrer, aBrowser);
   return IPC_OK();
@@ -4185,9 +4185,9 @@ nsresult ContentParent::DoSendAsyncMessage(JSContext* aCx,
 
 mozilla::ipc::IPCResult ContentParent::RecvKeywordToURI(
     const nsCString& aKeyword, nsString* aProviderName,
-    RefPtr<nsIInputStream>* aPostData, OptionalURIParams* aURI) {
+    RefPtr<nsIInputStream>* aPostData, Maybe<URIParams>* aURI) {
   *aPostData = nullptr;
-  *aURI = void_t();
+  *aURI = Nothing();
 
   nsCOMPtr<nsIURIFixup> fixup = components::URIFixup::Service();
   if (!fixup) {
@@ -4872,7 +4872,7 @@ mozilla::ipc::IPCResult ContentParent::RecvCreateWindow(
     PBrowserParent* aThisTab, PBrowserParent* aNewTab,
     const uint32_t& aChromeFlags, const bool& aCalledFromJS,
     const bool& aPositionSpecified, const bool& aSizeSpecified,
-    const OptionalURIParams& aURIToLoad, const nsCString& aFeatures,
+    const Maybe<URIParams>& aURIToLoad, const nsCString& aFeatures,
     const nsCString& aBaseURI, const float& aFullZoom,
     const IPC::Principal& aTriggeringPrincipal, nsIContentSecurityPolicy* aCsp,
     const uint32_t& aReferrerPolicy, CreateWindowResolver&& aResolve) {
@@ -4952,7 +4952,7 @@ mozilla::ipc::IPCResult ContentParent::RecvCreateWindow(
 mozilla::ipc::IPCResult ContentParent::RecvCreateWindowInDifferentProcess(
     PBrowserParent* aThisTab, const uint32_t& aChromeFlags,
     const bool& aCalledFromJS, const bool& aPositionSpecified,
-    const bool& aSizeSpecified, const OptionalURIParams& aURIToLoad,
+    const bool& aSizeSpecified, const Maybe<URIParams>& aURIToLoad,
     const nsCString& aFeatures, const nsCString& aBaseURI,
     const float& aFullZoom, const nsString& aName,
     const IPC::Principal& aTriggeringPrincipal, nsIContentSecurityPolicy* aCsp,
diff --git a/dom/ipc/ContentParent.h b/dom/ipc/ContentParent.h
index baddb7aa683a..042d4e98a919 100644
--- a/dom/ipc/ContentParent.h
+++ b/dom/ipc/ContentParent.h
@@ -81,7 +81,6 @@ class PrintingParent;
 
 namespace ipc {
 class CrashReporterHost;
-class OptionalURIParams;
 class PFileDescriptorSetParent;
 class URIParams;
 class TestShellParent;
@@ -130,7 +129,6 @@ class ContentParent final : public PContentParent,
                             public CPOWManagerGetter,
                             public mozilla::ipc::IShmemAllocator {
   typedef mozilla::ipc::GeckoChildProcessHost GeckoChildProcessHost;
-  typedef mozilla::ipc::OptionalURIParams OptionalURIParams;
   typedef mozilla::ipc::PFileDescriptorSetParent PFileDescriptorSetParent;
   typedef mozilla::ipc::TestShellParent TestShellParent;
   typedef mozilla::ipc::URIParams URIParams;
@@ -514,7 +512,7 @@ class ContentParent final : public PContentParent,
       PBrowserParent* aThisTabParent, PBrowserParent* aNewTab,
       const uint32_t& aChromeFlags, const bool& aCalledFromJS,
       const bool& aPositionSpecified, const bool& aSizeSpecified,
-      const OptionalURIParams& aURIToLoad, const nsCString& aFeatures,
+      const Maybe<URIParams>& aURIToLoad, const nsCString& aFeatures,
       const nsCString& aBaseURI, const float& aFullZoom,
       const IPC::Principal& aTriggeringPrincipal,
       nsIContentSecurityPolicy* aCsp, const uint32_t& aReferrerPolicy,
@@ -523,7 +521,7 @@ class ContentParent final : public PContentParent,
   mozilla::ipc::IPCResult RecvCreateWindowInDifferentProcess(
       PBrowserParent* aThisTab, const uint32_t& aChromeFlags,
       const bool& aCalledFromJS, const bool& aPositionSpecified,
-      const bool& aSizeSpecified, const OptionalURIParams& aURIToLoad,
+      const bool& aSizeSpecified, const Maybe<URIParams>& aURIToLoad,
       const nsCString& aFeatures, const nsCString& aBaseURI,
       const float& aFullZoom, const nsString& aName,
       const IPC::Principal& aTriggeringPrincipal,
@@ -875,24 +873,24 @@ class ContentParent final : public PContentParent,
       PPSMContentDownloaderParent* aDownloader);
 
   PExternalHelperAppParent* AllocPExternalHelperAppParent(
-      const OptionalURIParams& aUri,
+      const Maybe<URIParams>& aUri,
       const Maybe<mozilla::net::LoadInfoArgs>& aLoadInfoArgs,
       const nsCString& aMimeContentType, const nsCString& aContentDisposition,
       const uint32_t& aContentDispositionHint,
       const nsString& aContentDispositionFilename, const bool& aForceSave,
       const int64_t& aContentLength, const bool& aWasFileChannel,
-      const OptionalURIParams& aReferrer, PBrowserParent* aBrowser);
+      const Maybe<URIParams>& aReferrer, PBrowserParent* aBrowser);
 
   bool DeallocPExternalHelperAppParent(PExternalHelperAppParent* aService);
 
   mozilla::ipc::IPCResult RecvPExternalHelperAppConstructor(
-      PExternalHelperAppParent* actor, const OptionalURIParams& uri,
+      PExternalHelperAppParent* actor, const Maybe<URIParams>& uri,
       const Maybe<LoadInfoArgs>& loadInfoArgs,
       const nsCString& aMimeContentType, const nsCString& aContentDisposition,
       const uint32_t& aContentDispositionHint,
       const nsString& aContentDispositionFilename, const bool& aForceSave,
       const int64_t& aContentLength, const bool& aWasFileChannel,
-      const OptionalURIParams& aReferrer, PBrowserParent* aBrowser) override;
+      const Maybe<URIParams>& aReferrer, PBrowserParent* aBrowser) override;
 
   PHandlerServiceParent* AllocPHandlerServiceParent();
 
@@ -1039,7 +1037,7 @@ class ContentParent final : public PContentParent,
   mozilla::ipc::IPCResult RecvKeywordToURI(const nsCString& aKeyword,
                                            nsString* aProviderName,
                                            RefPtr<nsIInputStream>* aPostData,
-                                           OptionalURIParams* aURI);
+                                           Maybe<URIParams>* aURI);
 
   mozilla::ipc::IPCResult RecvNotifyKeywordSearchLoading(
       const nsString& aProvider, const nsString& aKeyword);
diff --git a/dom/ipc/PBrowser.ipdl b/dom/ipc/PBrowser.ipdl
index 5f1e5abf0ab5..18daebc50a13 100644
--- a/dom/ipc/PBrowser.ipdl
+++ b/dom/ipc/PBrowser.ipdl
@@ -935,7 +935,7 @@ child:
 
 parent:
     /** Records a history visit. */
-    async VisitURI(URIParams aURI, OptionalURIParams aLastVisitedURI,
+    async VisitURI(URIParams aURI, URIParams? aLastVisitedURI,
                    uint32_t aFlags);
 
     /** Fetches the visited status for an array of URIs (Android-only). */
diff --git a/dom/ipc/PContent.ipdl b/dom/ipc/PContent.ipdl
index ab799a427505..6e588a2fe425 100644
--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -277,7 +277,7 @@ struct XPCOMInitData
     nsString[] dictionaries;
     ClipboardCapabilities clipboardCaps;
     DomainPolicyClone domainPolicy;
-    OptionalURIParams userContentSheetURL;
+    URIParams? userContentSheetURL;
     GfxVarUpdate[] gfxNonDefaultVarUpdates;
     ContentDeviceData contentDeviceData;
     GfxInfoFeatureStatus[] gfxFeatureStatus;
@@ -587,7 +587,7 @@ child:
                          LayoutDeviceIntPoint aDragEndPoint,
                          uint32_t aKeyModifiers);
 
-    async DomainSetChanged(uint32_t aSetType, uint32_t aChangeType, OptionalURIParams aDomain);
+    async DomainSetChanged(uint32_t aSetType, uint32_t aChangeType, URIParams? aDomain);
 
     /**
      * Notify the child to shutdown. The child will in turn call FinishShutdown
@@ -901,7 +901,7 @@ parent:
 
     async PPSMContentDownloader(uint32_t aCertType);
 
-    async PExternalHelperApp(OptionalURIParams uri,
+    async PExternalHelperApp(URIParams? uri,
                              LoadInfoArgs? loadInfoArgs,
                              nsCString aMimeContentType,
                              nsCString aContentDisposition,
@@ -910,7 +910,7 @@ parent:
                              bool aForceSave,
                              int64_t aContentLength,
                              bool aWasFileChannel,
-                             OptionalURIParams aReferrer,
+                             URIParams? aReferrer,
                              nullable PBrowser aBrowser);
 
     async PHandlerService();
@@ -971,7 +971,7 @@ parent:
     async DeviceReset();
 
     sync KeywordToURI(nsCString keyword)
-        returns (nsString providerName, nsIInputStream postData, OptionalURIParams uri);
+        returns (nsString providerName, nsIInputStream postData, URIParams? uri);
 
     sync NotifyKeywordSearchLoading(nsString providerName, nsString keyword);
 
@@ -1120,7 +1120,7 @@ parent:
                        bool aCalledFromJS,
                        bool aPositionSpecified,
                        bool aSizeSpecified,
-                       OptionalURIParams aURIToLoad,
+                       URIParams? aURIToLoad,
                        nsCString aFeatures,
                        nsCString aBaseURI,
                        float aFullZoom,
@@ -1135,7 +1135,7 @@ parent:
       bool aCalledFromJS,
       bool aPositionSpecified,
       bool aSizeSpecified,
-      OptionalURIParams aURIToLoad,
+      URIParams? aURIToLoad,
       nsCString aFeatures,
       nsCString aBaseURI,
       float aFullZoom,
diff --git a/dom/ipc/TabParent.cpp b/dom/ipc/TabParent.cpp
index a7b74971e25f..c02ba8c53e2f 100644
--- a/dom/ipc/TabParent.cpp
+++ b/dom/ipc/TabParent.cpp
@@ -3393,7 +3393,7 @@ mozilla::ipc::IPCResult TabParent::RecvShowCanvasPermissionPrompt(
 }
 
 mozilla::ipc::IPCResult TabParent::RecvVisitURI(
-    const URIParams& aURI, const OptionalURIParams& aLastVisitedURI,
+    const URIParams& aURI, const Maybe<URIParams>& aLastVisitedURI,
     const uint32_t& aFlags) {
   nsCOMPtr<nsIURI> ourURI = DeserializeURI(aURI);
   if (!ourURI) {
diff --git a/dom/ipc/TabParent.h b/dom/ipc/TabParent.h
index 248430160ceb..1f98d7b0c662 100644
--- a/dom/ipc/TabParent.h
+++ b/dom/ipc/TabParent.h
@@ -626,7 +626,7 @@ class TabParent final : public PBrowserParent,
   mozilla::ipc::IPCResult RecvGetSystemFont(nsCString* aFontName);
 
   mozilla::ipc::IPCResult RecvVisitURI(const URIParams& aURI,
-                                       const OptionalURIParams& aLastVisitedURI,
+                                       const Maybe<URIParams>& aLastVisitedURI,
                                        const uint32_t& aFlags);
 
   mozilla::ipc::IPCResult RecvQueryVisitedState(
diff --git a/dom/jsurl/nsJSProtocolHandler.cpp b/dom/jsurl/nsJSProtocolHandler.cpp
index 843c2e5d0ba0..0d6668581370 100644
--- a/dom/jsurl/nsJSProtocolHandler.cpp
+++ b/dom/jsurl/nsJSProtocolHandler.cpp
@@ -51,6 +51,7 @@
 #include "nsILoadInfo.h"
 #include "nsContentSecurityManager.h"
 
+#include "mozilla/Maybe.h"
 #include "mozilla/ipc/URIUtils.h"
 
 using mozilla::dom::AutoEntryScript;
@@ -1231,7 +1232,7 @@ NS_IMETHODIMP_(void) nsJSURI::Serialize(mozilla::ipc::URIParams& aParams) {
   if (mBaseURI) {
     SerializeURI(mBaseURI, jsParams.baseURI());
   } else {
-    jsParams.baseURI() = mozilla::void_t();
+    jsParams.baseURI() = mozilla::Nothing();
   }
 
   aParams = jsParams;
@@ -1248,8 +1249,8 @@ bool nsJSURI::Deserialize(const mozilla::ipc::URIParams& aParams) {
   const JSURIParams& jsParams = aParams.get_JSURIParams();
   mozilla::net::nsSimpleURI::Deserialize(jsParams.simpleParams());
 
-  if (jsParams.baseURI().type() != OptionalURIParams::Tvoid_t) {
-    mBaseURI = DeserializeURI(jsParams.baseURI().get_URIParams());
+  if (jsParams.baseURI().isSome()) {
+    mBaseURI = DeserializeURI(jsParams.baseURI().ref());
   } else {
     mBaseURI = nullptr;
   }
diff --git a/image/decoders/icon/nsIconURI.cpp b/image/decoders/icon/nsIconURI.cpp
index a5e02c8fd017..d65e6f510c95 100644
--- a/image/decoders/icon/nsIconURI.cpp
+++ b/image/decoders/icon/nsIconURI.cpp
@@ -552,9 +552,9 @@ void nsMozIconURI::Serialize(URIParams& aParams) {
       return;
     }
 
-    params.uri() = iconURLParams;
+    params.uri() = Some(std::move(iconURLParams));
   } else {
-    params.uri() = void_t();
+    params.uri() = Nothing();
   }
 
   params.size() = mSize;
@@ -573,8 +573,8 @@ bool nsMozIconURI::Deserialize(const URIParams& aParams) {
   }
 
   const IconURIParams& params = aParams.get_IconURIParams();
-  if (params.uri().type() != OptionalURIParams::Tvoid_t) {
-    nsCOMPtr<nsIURI> uri = DeserializeURI(params.uri().get_URIParams());
+  if (params.uri().isSome()) {
+    nsCOMPtr<nsIURI> uri = DeserializeURI(params.uri().ref());
     mIconURL = do_QueryInterface(uri);
     if (!mIconURL) {
       MOZ_ASSERT_UNREACHABLE("bad nsIURI passed");
diff --git a/ipc/glue/BackgroundUtils.cpp b/ipc/glue/BackgroundUtils.cpp
index bb5a815d4268..e5b68cb46255 100644
--- a/ipc/glue/BackgroundUtils.cpp
+++ b/ipc/glue/BackgroundUtils.cpp
@@ -424,7 +424,7 @@ nsresult LoadInfoToLoadInfoArgs(nsILoadInfo* aLoadInfo,
         Some(topLevelStorageAreaPrincipalInfoTemp);
   }
 
-  OptionalURIParams optionalResultPrincipalURI = mozilla::void_t();
+  Maybe<URIParams> optionalResultPrincipalURI;
   nsCOMPtr<nsIURI> resultPrincipalURI;
   Unused << aLoadInfo->GetResultPrincipalURI(
       getter_AddRefs(resultPrincipalURI));
@@ -573,7 +573,7 @@ nsresult LoadInfoArgsToLoadInfo(
   }
 
   nsCOMPtr<nsIURI> resultPrincipalURI;
-  if (loadInfoArgs.resultPrincipalURI().type() != OptionalURIParams::Tvoid_t) {
+  if (loadInfoArgs.resultPrincipalURI().isSome()) {
     resultPrincipalURI = DeserializeURI(loadInfoArgs.resultPrincipalURI());
     NS_ENSURE_TRUE(resultPrincipalURI, NS_ERROR_UNEXPECTED);
   }
diff --git a/ipc/glue/URIParams.ipdlh b/ipc/glue/URIParams.ipdlh
index 0c68667f080e..fd27459669f4 100644
--- a/ipc/glue/URIParams.ipdlh
+++ b/ipc/glue/URIParams.ipdlh
@@ -54,7 +54,7 @@ struct JARURIParams
 
 struct IconURIParams
 {
-  OptionalURIParams uri;
+  URIParams? uri;
   uint32_t size;
   nsCString contentType;
   nsCString fileName;
@@ -86,16 +86,10 @@ union URIParams
   HostObjectURIParams;
 };
 
-union OptionalURIParams
-{
-  void_t;
-  URIParams;
-};
-
 struct JSURIParams
 {
   SimpleURIParams simpleParams;
-  OptionalURIParams baseURI;
+  URIParams? baseURI;
 };
 
 struct SimpleNestedURIParams
diff --git a/ipc/glue/URIUtils.cpp b/ipc/glue/URIUtils.cpp
index adc130cdc06d..e5755be0db18 100644
--- a/ipc/glue/URIUtils.cpp
+++ b/ipc/glue/URIUtils.cpp
@@ -46,15 +46,15 @@ void SerializeURI(nsIURI* aURI, URIParams& aParams) {
   }
 }
 
-void SerializeURI(nsIURI* aURI, OptionalURIParams& aParams) {
+void SerializeURI(nsIURI* aURI, Maybe<URIParams>& aParams) {
   MOZ_ASSERT(NS_IsMainThread());
 
   if (aURI) {
     URIParams params;
     SerializeURI(aURI, params);
-    aParams = params;
+    aParams = Some(std::move(params));
   } else {
-    aParams = mozilla::void_t();
+    aParams = Nothing();
   }
 }
 
@@ -116,21 +116,13 @@ already_AddRefed<nsIURI> DeserializeURI(const URIParams& aParams) {
   return uri.forget();
 }
 
-already_AddRefed<nsIURI> DeserializeURI(const OptionalURIParams& aParams) {
+already_AddRefed<nsIURI> DeserializeURI(const Maybe<URIParams>& aParams) {
   MOZ_ASSERT(NS_IsMainThread());
 
   nsCOMPtr<nsIURI> uri;
 
-  switch (aParams.type()) {
-    case OptionalURIParams::Tvoid_t:
-      break;
-
-    case OptionalURIParams::TURIParams:
-      uri = DeserializeURI(aParams.get_URIParams());
-      break;
-
-    default:
-      MOZ_CRASH("Unknown params!");
+  if (aParams.isSome()) {
+    uri = DeserializeURI(aParams.ref());
   }
 
   return uri.forget();
diff --git a/ipc/glue/URIUtils.h b/ipc/glue/URIUtils.h
index 50daf162f6b0..98619c60df89 100644
--- a/ipc/glue/URIUtils.h
+++ b/ipc/glue/URIUtils.h
@@ -17,23 +17,23 @@ namespace ipc {
 
 void SerializeURI(nsIURI* aURI, URIParams& aParams);
 
-void SerializeURI(nsIURI* aURI, OptionalURIParams& aParams);
+void SerializeURI(nsIURI* aURI, Maybe<URIParams>& aParams);
 
 already_AddRefed<nsIURI> DeserializeURI(const URIParams& aParams);
 
-already_AddRefed<nsIURI> DeserializeURI(const OptionalURIParams& aParams);
+already_AddRefed<nsIURI> DeserializeURI(const Maybe<URIParams>& aParams);
 
 template <>
 struct IPDLParamTraits<nsIURI> {
   static void Write(IPC::Message* aMsg, IProtocol* aActor, nsIURI* aParam) {
-    OptionalURIParams params;
+    Maybe<URIParams> params;
     SerializeURI(aParam, params);
     WriteIPDLParam(aMsg, aActor, params);
   }
 
   static bool Read(const IPC::Message* aMsg, PickleIterator* aIter,
                    IProtocol* aActor, RefPtr<nsIURI>* aResult) {
-    OptionalURIParams params;
+    Maybe<URIParams> params;
     if (!ReadIPDLParam(aMsg, aIter, aActor, &params)) {
       return false;
     }
diff --git a/mobile/android/components/geckoview/GeckoViewHistory.cpp b/mobile/android/components/geckoview/GeckoViewHistory.cpp
index 9eff3a6db4a4..ad783faff5d0 100644
--- a/mobile/android/components/geckoview/GeckoViewHistory.cpp
+++ b/mobile/android/components/geckoview/GeckoViewHistory.cpp
@@ -360,7 +360,7 @@ GeckoViewHistory::VisitURI(nsIWidget* aWidget, nsIURI* aURI,
     URIParams uri;
     SerializeURI(aURI, uri);
 
-    OptionalURIParams lastVisitedURI;
+    Maybe<URIParams> lastVisitedURI;
     SerializeURI(aLastVisitedURI, lastVisitedURI);
 
     // If we're in the content process, send the visit to the parent. The parent
diff --git a/netwerk/base/Predictor.cpp b/netwerk/base/Predictor.cpp
index f963d638c101..74d8b749faf5 100644
--- a/netwerk/base/Predictor.cpp
+++ b/netwerk/base/Predictor.cpp
@@ -539,7 +539,7 @@ class PredictorLearnRunnable final : public Runnable {
     ipc::URIParams serTargetURI;
     SerializeURI(mTargetURI, serTargetURI);
 
-    ipc::OptionalURIParams serSourceURI;
+    Maybe<ipc::URIParams> serSourceURI;
     SerializeURI(mSourceURI, serSourceURI);
 
     PREDICTOR_LOG(("predictor::learn (async) forwarding to parent"));
@@ -657,7 +657,7 @@ Predictor::PredictNative(nsIURI *targetURI, nsIURI *sourceURI,
 
     PREDICTOR_LOG(("    called on child process"));
 
-    ipc::OptionalURIParams serTargetURI, serSourceURI;
+    Maybe<ipc::URIParams> serTargetURI, serSourceURI;
     SerializeURI(targetURI, serTargetURI);
     SerializeURI(sourceURI, serSourceURI);
 
diff --git a/netwerk/cookie/CookieServiceChild.cpp b/netwerk/cookie/CookieServiceChild.cpp
index 8216594af8f6..663dbf9ce058 100644
--- a/netwerk/cookie/CookieServiceChild.cpp
+++ b/netwerk/cookie/CookieServiceChild.cpp
@@ -549,7 +549,7 @@ nsresult CookieServiceChild::SetCookieStringInternal(nsIURI *aHostURI,
   URIParams hostURIParams;
   SerializeURI(aHostURI, hostURIParams);
 
-  OptionalURIParams channelURIParams;
+  Maybe<URIParams> channelURIParams;
   mozilla::OriginAttributes attrs;
   if (aChannel) {
     nsCOMPtr<nsIURI> channelURI;
diff --git a/netwerk/cookie/CookieServiceParent.cpp b/netwerk/cookie/CookieServiceParent.cpp
index 717ac4781d6c..da0074690968 100644
--- a/netwerk/cookie/CookieServiceParent.cpp
+++ b/netwerk/cookie/CookieServiceParent.cpp
@@ -215,7 +215,7 @@ void CookieServiceParent::ActorDestroy(ActorDestroyReason aWhy) {
 }
 
 mozilla::ipc::IPCResult CookieServiceParent::RecvSetCookieString(
-    const URIParams &aHost, const OptionalURIParams &aChannelURI,
+    const URIParams &aHost, const Maybe<URIParams> &aChannelURI,
     const bool &aIsForeign, const bool &aIsTrackingResource,
     const bool &aFirstPartyStorageAccessGranted, const nsCString &aCookieString,
     const nsCString &aServerTime, const OriginAttributes &aAttrs,
diff --git a/netwerk/cookie/CookieServiceParent.h b/netwerk/cookie/CookieServiceParent.h
index cbf2693b8e9e..f2870de1b2df 100644
--- a/netwerk/cookie/CookieServiceParent.h
+++ b/netwerk/cookie/CookieServiceParent.h
@@ -45,7 +45,7 @@ class CookieServiceParent : public PCookieServiceParent {
   virtual void ActorDestroy(ActorDestroyReason aWhy) override;
 
   mozilla::ipc::IPCResult RecvSetCookieString(
-      const URIParams &aHost, const OptionalURIParams &aChannelURI,
+      const URIParams &aHost, const Maybe<URIParams> &aChannelURI,
       const bool &aIsForeign, const bool &aIsTrackingResource,
       const bool &aFirstPartyStorageAccessGranted,
       const nsCString &aCookieString, const nsCString &aServerTime,
diff --git a/netwerk/cookie/PCookieService.ipdl b/netwerk/cookie/PCookieService.ipdl
index 344bbe08ffb9..be31efb7c362 100644
--- a/netwerk/cookie/PCookieService.ipdl
+++ b/netwerk/cookie/PCookieService.ipdl
@@ -71,7 +71,7 @@ parent:
    * @see mozIThirdPartyUtil.isThirdPartyChannel
    */
   nested(inside_cpow) async SetCookieString(URIParams host,
-                                            OptionalURIParams channelURI,
+                                            URIParams? channelURI,
                                             bool isForeign,
                                             bool isTrackingResource,
                                             bool firstPartyStorageAccessGranted,
diff --git a/netwerk/ipc/NeckoChannelParams.ipdlh b/netwerk/ipc/NeckoChannelParams.ipdlh
index 793e9aff21f4..d9c8323791fd 100644
--- a/netwerk/ipc/NeckoChannelParams.ipdlh
+++ b/netwerk/ipc/NeckoChannelParams.ipdlh
@@ -45,7 +45,7 @@ struct PreferredAlternativeDataTypeParams
 struct RedirectHistoryEntryInfo
 {
   PrincipalInfo       principalInfo;
-  OptionalURIParams   referrerUri;
+  URIParams?          referrerUri;
   nsCString           remoteAddress;
 };
 
@@ -57,7 +57,7 @@ struct LoadInfoArgs
   PrincipalInfo?              sandboxedLoadingPrincipalInfo;
   PrincipalInfo?              topLevelPrincipalInfo;
   PrincipalInfo?              topLevelStorageAreaPrincipalInfo;
-  OptionalURIParams           resultPrincipalURI;
+  URIParams?                  resultPrincipalURI;
   uint32_t                    securityFlags;
   uint32_t                    contentPolicyType;
   uint32_t                    tainting;
@@ -209,12 +209,12 @@ struct HttpChannelOpenArgs
   // - TODO: bug 571161: unclear if any HTTP channel clients ever
   // set originalURI != uri (about:credits?); also not clear if
   // chrome channel would ever need to know.  Get rid of next arg?
-  OptionalURIParams           original;
-  OptionalURIParams           doc;
-  OptionalURIParams           originalReferrer;
+  URIParams?                  original;
+  URIParams?                  doc;
+  URIParams?                  originalReferrer;
   uint32_t                    referrerPolicy;
-  OptionalURIParams           apiRedirectTo;
-  OptionalURIParams           topWindowURI;
+  URIParams?                  apiRedirectTo;
+  URIParams?                  topWindowURI;
   nsIPrincipal                topWindowPrincipal;
   uint32_t                    loadFlags;
   RequestHeaderTuples         requestHeaders;
diff --git a/netwerk/ipc/NeckoParent.cpp b/netwerk/ipc/NeckoParent.cpp
index a40e70c124b4..1c0b08c17e20 100644
--- a/netwerk/ipc/NeckoParent.cpp
+++ b/netwerk/ipc/NeckoParent.cpp
@@ -743,8 +743,8 @@ mozilla::ipc::IPCResult NeckoParent::RecvOnAuthCancelled(
 
 /* Predictor Messages */
 mozilla::ipc::IPCResult NeckoParent::RecvPredPredict(
-    const ipc::OptionalURIParams& aTargetURI,
-    const ipc::OptionalURIParams& aSourceURI, const uint32_t& aReason,
+    const Maybe<ipc::URIParams>& aTargetURI,
+    const Maybe<ipc::URIParams>& aSourceURI, const uint32_t& aReason,
     const OriginAttributes& aOriginAttributes, const bool& hasVerifier) {
   nsCOMPtr<nsIURI> targetURI = DeserializeURI(aTargetURI);
   nsCOMPtr<nsIURI> sourceURI = DeserializeURI(aSourceURI);
@@ -765,7 +765,7 @@ mozilla::ipc::IPCResult NeckoParent::RecvPredPredict(
 }
 
 mozilla::ipc::IPCResult NeckoParent::RecvPredLearn(
-    const ipc::URIParams& aTargetURI, const ipc::OptionalURIParams& aSourceURI,
+    const ipc::URIParams& aTargetURI, const Maybe<ipc::URIParams>& aSourceURI,
     const uint32_t& aReason, const OriginAttributes& aOriginAttributes) {
   nsCOMPtr<nsIURI> targetURI = DeserializeURI(aTargetURI);
   nsCOMPtr<nsIURI> sourceURI = DeserializeURI(aSourceURI);
diff --git a/netwerk/ipc/NeckoParent.h b/netwerk/ipc/NeckoParent.h
index fa956839bb18..6f07a75a4549 100644
--- a/netwerk/ipc/NeckoParent.h
+++ b/netwerk/ipc/NeckoParent.h
@@ -200,14 +200,13 @@ class NeckoParent : public PNeckoParent {
 
   /* Predictor Messages */
   mozilla::ipc::IPCResult RecvPredPredict(
-      const ipc::OptionalURIParams& aTargetURI,
-      const ipc::OptionalURIParams& aSourceURI,
+      const Maybe<ipc::URIParams>& aTargetURI,
+      const Maybe<ipc::URIParams>& aSourceURI,
       const PredictorPredictReason& aReason,
       const OriginAttributes& aOriginAttributes, const bool& hasVerifier);
 
   mozilla::ipc::IPCResult RecvPredLearn(
-      const ipc::URIParams& aTargetURI,
-      const ipc::OptionalURIParams& aSourceURI,
+      const ipc::URIParams& aTargetURI, const Maybe<ipc::URIParams>& aSourceURI,
       const PredictorPredictReason& aReason,
       const OriginAttributes& aOriginAttributes);
   mozilla::ipc::IPCResult RecvPredReset();
diff --git a/netwerk/ipc/PNecko.ipdl b/netwerk/ipc/PNecko.ipdl
index ef5c7d31d32e..392b2789ad76 100644
--- a/netwerk/ipc/PNecko.ipdl
+++ b/netwerk/ipc/PNecko.ipdl
@@ -88,10 +88,10 @@ parent:
   async PWebSocketEventListener(uint64_t aInnerWindowID);
 
   /* Predictor Methods */
-  async PredPredict(OptionalURIParams targetURI, OptionalURIParams sourceURI,
+  async PredPredict(URIParams? targetURI, URIParams? sourceURI,
                     uint32_t reason, OriginAttributes originAttributes,
                     bool hasVerifier);
-  async PredLearn(URIParams targetURI, OptionalURIParams sourceURI,
+  async PredLearn(URIParams targetURI, URIParams? sourceURI,
                   uint32_t reason, OriginAttributes originAttributes);
   async PredReset();
 
diff --git a/netwerk/protocol/http/HttpChannelChild.cpp b/netwerk/protocol/http/HttpChannelChild.cpp
index 203a05d4ee2c..55d550b2ff97 100644
--- a/netwerk/protocol/http/HttpChannelChild.cpp
+++ b/netwerk/protocol/http/HttpChannelChild.cpp
@@ -2141,11 +2141,11 @@ NS_IMETHODIMP
 HttpChannelChild::OnRedirectVerifyCallback(nsresult result) {
   LOG(("HttpChannelChild::OnRedirectVerifyCallback [this=%p]\n", this));
   MOZ_ASSERT(NS_IsMainThread());
-  OptionalURIParams redirectURI;
+  Maybe<URIParams> redirectURI;
   nsresult rv;
 
   uint32_t referrerPolicy = REFERRER_POLICY_UNSET;
-  OptionalURIParams referrerURI;
+  Maybe<URIParams> referrerURI;
   SerializeURI(nullptr, referrerURI);
 
   nsCOMPtr<nsIHttpChannel> newHttpChannel =
diff --git a/netwerk/protocol/http/HttpChannelParent.cpp b/netwerk/protocol/http/HttpChannelParent.cpp
index fb5f2af1c96a..0925d10ddbb7 100644
--- a/netwerk/protocol/http/HttpChannelParent.cpp
+++ b/netwerk/protocol/http/HttpChannelParent.cpp
@@ -382,11 +382,11 @@ void HttpChannelParent::InvokeAsyncOpen(nsresult rv) {
 }
 
 bool HttpChannelParent::DoAsyncOpen(
-    const URIParams& aURI, const OptionalURIParams& aOriginalURI,
-    const OptionalURIParams& aDocURI,
-    const OptionalURIParams& aOriginalReferrerURI,
-    const uint32_t& aReferrerPolicy, const OptionalURIParams& aAPIRedirectToURI,
-    const OptionalURIParams& aTopWindowURI, nsIPrincipal* aTopWindowPrincipal,
+    const URIParams& aURI, const Maybe<URIParams>& aOriginalURI,
+    const Maybe<URIParams>& aDocURI,
+    const Maybe<URIParams>& aOriginalReferrerURI,
+    const uint32_t& aReferrerPolicy, const Maybe<URIParams>& aAPIRedirectToURI,
+    const Maybe<URIParams>& aTopWindowURI, nsIPrincipal* aTopWindowPrincipal,
     const uint32_t& aLoadFlags, const RequestHeaderTuples& requestHeaders,
     const nsCString& requestMethod, const Maybe<IPCStream>& uploadStream,
     const bool& uploadStreamHasHeaders, const int16_t& priority,
@@ -827,8 +827,8 @@ mozilla::ipc::IPCResult HttpChannelParent::RecvRedirect2Verify(
     const nsresult& aResult, const RequestHeaderTuples& changedHeaders,
     const ChildLoadInfoForwarderArgs& aLoadInfoForwarder,
     const uint32_t& loadFlags, const uint32_t& referrerPolicy,
-    const OptionalURIParams& aReferrerURI,
-    const OptionalURIParams& aAPIRedirectURI,
+    const Maybe<URIParams>& aReferrerURI,
+    const Maybe<URIParams>& aAPIRedirectURI,
     const OptionalCorsPreflightArgs& aCorsPreflightArgs,
     const bool& aChooseAppcache) {
   LOG(("HttpChannelParent::RecvRedirect2Verify [this=%p result=%" PRIx32 "]\n",
diff --git a/netwerk/protocol/http/HttpChannelParent.h b/netwerk/protocol/http/HttpChannelParent.h
index 06909b3f55b6..0c6b455aee82 100644
--- a/netwerk/protocol/http/HttpChannelParent.h
+++ b/netwerk/protocol/http/HttpChannelParent.h
@@ -138,12 +138,12 @@ class HttpChannelParent final : public nsIInterfaceRequestor,
                                    const bool& shouldIntercept);
 
   MOZ_MUST_USE bool DoAsyncOpen(
-      const URIParams& uri, const OptionalURIParams& originalUri,
-      const OptionalURIParams& docUri,
-      const OptionalURIParams& originalReferrerUri,
+      const URIParams& uri, const Maybe<URIParams>& originalUri,
+      const Maybe<URIParams>& docUri,
+      const Maybe<URIParams>& originalReferrerUri,
       const uint32_t& referrerPolicy,
-      const OptionalURIParams& internalRedirectUri,
-      const OptionalURIParams& topWindowUri, nsIPrincipal* aTopWindowPrincipal,
+      const Maybe<URIParams>& internalRedirectUri,
+      const Maybe<URIParams>& topWindowUri, nsIPrincipal* aTopWindowPrincipal,
       const uint32_t& loadFlags, const RequestHeaderTuples& requestHeaders,
       const nsCString& requestMethod, const Maybe<IPCStream>& uploadStream,
       const bool& uploadStreamHasHeaders, const int16_t& priority,
@@ -189,8 +189,8 @@ class HttpChannelParent final : public nsIInterfaceRequestor,
       const nsresult& result, const RequestHeaderTuples& changedHeaders,
       const ChildLoadInfoForwarderArgs& aLoadInfoForwarder,
       const uint32_t& loadFlags, const uint32_t& referrerPolicy,
-      const OptionalURIParams& aReferrerURI,
-      const OptionalURIParams& apiRedirectUri,
+      const Maybe<URIParams>& aReferrerURI,
+      const Maybe<URIParams>& apiRedirectUri,
       const OptionalCorsPreflightArgs& aCorsPreflightArgs,
       const bool& aChooseAppcache) override;
   virtual mozilla::ipc::IPCResult RecvDocumentChannelCleanup(
diff --git a/netwerk/protocol/http/PHttpChannel.ipdl b/netwerk/protocol/http/PHttpChannel.ipdl
index 0e1ada9ca120..938f0a8576e3 100644
--- a/netwerk/protocol/http/PHttpChannel.ipdl
+++ b/netwerk/protocol/http/PHttpChannel.ipdl
@@ -45,8 +45,7 @@ parent:
   async Redirect2Verify(nsresult result, RequestHeaderTuples changedHeaders,
                         ChildLoadInfoForwarderArgs loadInfoForwarder,
                         uint32_t loadFlags, uint32_t referrerPolicy,
-                        OptionalURIParams referrerUri,
-                        OptionalURIParams apiRedirectTo,
+                        URIParams? referrerUri, URIParams? apiRedirectTo,
                         OptionalCorsPreflightArgs corsPreflightArgs,
                         bool chooseAppcache);
 
diff --git a/netwerk/protocol/websocket/PWebSocket.ipdl b/netwerk/protocol/websocket/PWebSocket.ipdl
index a2993c6bb471..0e1cce98a956 100644
--- a/netwerk/protocol/websocket/PWebSocket.ipdl
+++ b/netwerk/protocol/websocket/PWebSocket.ipdl
@@ -34,7 +34,7 @@ async protocol PWebSocket
 
 parent:
   // Forwarded methods corresponding to methods on nsIWebSocketChannel
-  async AsyncOpen(OptionalURIParams aURI,
+  async AsyncOpen(URIParams? aURI,
                   nsCString aOrigin,
                   uint64_t aInnerWindowID,
                   nsCString aProtocol,
diff --git a/netwerk/protocol/websocket/WebSocketChannelChild.cpp b/netwerk/protocol/websocket/WebSocketChannelChild.cpp
index 1498e8af3e01..42b86459318b 100644
--- a/netwerk/protocol/websocket/WebSocketChannelChild.cpp
+++ b/netwerk/protocol/websocket/WebSocketChannelChild.cpp
@@ -444,21 +444,18 @@ WebSocketChannelChild::AsyncOpen(nsIURI* aURI, const nsACString& aOrigin,
   // Corresponding release in DeallocPWebSocket
   AddIPDLReference();
 
-  OptionalURIParams uri;
+  Maybe<URIParams> uri;
   Maybe<LoadInfoArgs> loadInfoArgs;
   OptionalTransportProvider transportProvider;
 
   if (!mIsServerSide) {
-    uri = URIParams();
-    SerializeURI(aURI, uri.get_URIParams());
+    uri.emplace(URIParams());
+    SerializeURI(aURI, uri.ref());
     nsresult rv = LoadInfoToLoadInfoArgs(mLoadInfo, &loadInfoArgs);
     NS_ENSURE_SUCCESS(rv, rv);
 
     transportProvider = void_t();
   } else {
-    uri = void_t();
-    loadInfoArgs = Nothing();
-
     MOZ_ASSERT(mServerTransportProvider);
     PTransportProviderChild* ipcChild;
     nsresult rv = mServerTransportProvider->GetIPCChild(&ipcChild);
diff --git a/netwerk/protocol/websocket/WebSocketChannelParent.cpp b/netwerk/protocol/websocket/WebSocketChannelParent.cpp
index 532a9c9cc2b4..d697a3839b56 100644
--- a/netwerk/protocol/websocket/WebSocketChannelParent.cpp
+++ b/netwerk/protocol/websocket/WebSocketChannelParent.cpp
@@ -48,7 +48,7 @@ mozilla::ipc::IPCResult WebSocketChannelParent::RecvDeleteSelf() {
 }
 
 mozilla::ipc::IPCResult WebSocketChannelParent::RecvAsyncOpen(
-    const OptionalURIParams& aURI, const nsCString& aOrigin,
+    const Maybe<URIParams>& aURI, const nsCString& aOrigin,
     const uint64_t& aInnerWindowID, const nsCString& aProtocol,
     const bool& aSecure, const uint32_t& aPingInterval,
     const bool& aClientSetPingInterval, const uint32_t& aPingTimeout,
diff --git a/netwerk/protocol/websocket/WebSocketChannelParent.h b/netwerk/protocol/websocket/WebSocketChannelParent.h
index ce8af4b2c833..efd4d717abc5 100644
--- a/netwerk/protocol/websocket/WebSocketChannelParent.h
+++ b/netwerk/protocol/websocket/WebSocketChannelParent.h
@@ -39,7 +39,7 @@ class WebSocketChannelParent : public PWebSocketParent,
 
  private:
   mozilla::ipc::IPCResult RecvAsyncOpen(
-      const OptionalURIParams& aURI, const nsCString& aOrigin,
+      const Maybe<URIParams>& aURI, const nsCString& aOrigin,
       const uint64_t& aInnerWindowID, const nsCString& aProtocol,
       const bool& aSecure, const uint32_t& aPingInterval,
       const bool& aClientSetPingInterval, const uint32_t& aPingTimeout,
diff --git a/toolkit/components/places/History.cpp b/toolkit/components/places/History.cpp
index 0927499b5570..6d8e33f8b1e4 100644
--- a/toolkit/components/places/History.cpp
+++ b/toolkit/components/places/History.cpp
@@ -2008,7 +2008,7 @@ History::VisitURI(nsIWidget* aWidget, nsIURI* aURI, nsIURI* aLastVisitedURI,
     URIParams uri;
     SerializeURI(aURI, uri);
 
-    OptionalURIParams lastVisitedURI;
+    Maybe<URIParams> lastVisitedURI;
     SerializeURI(aLastVisitedURI, lastVisitedURI);
 
     NS_ENSURE_ARG(aWidget);
diff --git a/uriloader/exthandler/ExternalHelperAppParent.cpp b/uriloader/exthandler/ExternalHelperAppParent.cpp
index 046cff58b943..455090109785 100644
--- a/uriloader/exthandler/ExternalHelperAppParent.cpp
+++ b/uriloader/exthandler/ExternalHelperAppParent.cpp
@@ -33,9 +33,8 @@ NS_IMPL_ISUPPORTS_INHERITED(ExternalHelperAppParent, nsHashPropertyBag,
                             nsIStreamListener, nsIExternalHelperAppParent)
 
 ExternalHelperAppParent::ExternalHelperAppParent(
-    const OptionalURIParams& uri,
-    const int64_t& aContentLength, const bool& aWasFileChannel,
-    const nsCString& aContentDispositionHeader,
+    const Maybe<URIParams>& uri, const int64_t& aContentLength,
+    const bool& aWasFileChannel, const nsCString& aContentDispositionHeader,
     const uint32_t& aContentDispositionHint,
     const nsString& aContentDispositionFilename)
     : mURI(DeserializeURI(uri)),
@@ -88,7 +87,7 @@ void UpdateContentContext(nsIStreamListener* aListener,
 void ExternalHelperAppParent::Init(
     const Maybe<mozilla::net::LoadInfoArgs>& aLoadInfoArgs,
     const nsCString& aMimeContentType, const bool& aForceSave,
-    const OptionalURIParams& aReferrer, PBrowserParent* aBrowser) {
+    const Maybe<URIParams>& aReferrer, PBrowserParent* aBrowser) {
   mozilla::ipc::LoadInfoArgsToLoadInfo(aLoadInfoArgs,
                                        getter_AddRefs(mLoadInfo));
 
diff --git a/uriloader/exthandler/ExternalHelperAppParent.h b/uriloader/exthandler/ExternalHelperAppParent.h
index baf729761533..66b15ea5bfed 100644
--- a/uriloader/exthandler/ExternalHelperAppParent.h
+++ b/uriloader/exthandler/ExternalHelperAppParent.h
@@ -20,7 +20,7 @@ class URI;
 namespace mozilla {
 
 namespace ipc {
-class OptionalURIParams;
+class URIParams;
 }  // namespace ipc
 
 namespace net {
@@ -61,7 +61,6 @@ class ExternalHelperAppParent
       public nsIStreamListener,
       public net::PrivateBrowsingChannel<ExternalHelperAppParent>,
       public nsIExternalHelperAppParent {
-  typedef mozilla::ipc::OptionalURIParams OptionalURIParams;
 
  public:
   NS_DECL_ISUPPORTS_INHERITED
@@ -84,15 +83,16 @@ class ExternalHelperAppParent
 
   bool WasFileChannel() override { return mWasFileChannel; }
 
-  ExternalHelperAppParent(
-      const OptionalURIParams& uri,
-      const int64_t& contentLength, const bool& wasFileChannel,
-      const nsCString& aContentDispositionHeader,
-      const uint32_t& aContentDispositionHint,
-      const nsString& aContentDispositionFilename);
+  ExternalHelperAppParent(const Maybe<mozilla::ipc::URIParams>& uri,
+                          const int64_t& contentLength,
+                          const bool& wasFileChannel,
+                          const nsCString& aContentDispositionHeader,
+                          const uint32_t& aContentDispositionHint,
+                          const nsString& aContentDispositionFilename);
   void Init(const Maybe<mozilla::net::LoadInfoArgs>& aLoadInfoArgs,
             const nsCString& aMimeContentType, const bool& aForceSave,
-            const OptionalURIParams& aReferrer, PBrowserParent* aBrowser);
+            const Maybe<mozilla::ipc::URIParams>& aReferrer,
+            PBrowserParent* aBrowser);
 
  protected:
   virtual ~ExternalHelperAppParent();
diff --git a/uriloader/exthandler/nsExternalHelperAppService.cpp b/uriloader/exthandler/nsExternalHelperAppService.cpp
index 1b221ba87c7f..6ee76a9d3e33 100644
--- a/uriloader/exthandler/nsExternalHelperAppService.cpp
+++ b/uriloader/exthandler/nsExternalHelperAppService.cpp
@@ -634,7 +634,7 @@ nsresult nsExternalHelperAppService::DoContentContentProcessHelper(
   nsCOMPtr<nsIURI> referrer;
   NS_GetReferrerFromChannel(channel, getter_AddRefs(referrer));
 
-  OptionalURIParams uriParams, referrerParams;
+  Maybe<URIParams> uriParams, referrerParams;
   SerializeURI(uri, uriParams);
   SerializeURI(referrer, referrerParams);