diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index 4782043b00e7..7caea90a1e50 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -922,13 +922,11 @@ ContentChild::InitXPCOM()
   ClipboardCapabilities clipboardCaps;
   DomainPolicyClone domainPolicy;
   StructuredCloneData initialData;
-  OptionalURIParams userContentSheetURL;
 
   SendGetXPCOMProcessAttributes(&isOffline, &isConnected,
                                 &isLangRTL, &haveBidiKeyboards,
                                 &mAvailableDictionaries,
-                                &clipboardCaps, &domainPolicy, &initialData,
-                                &userContentSheetURL);
+                                &clipboardCaps, &domainPolicy, &initialData);
   RecvSetOffline(isOffline);
   RecvSetConnectivity(isConnected);
   RecvBidiKeyboardNotify(isLangRTL, haveBidiKeyboards);
@@ -966,10 +964,6 @@ ContentChild::InitXPCOM()
     global->SetInitialProcessData(data);
   }
 
-  // The stylesheet cache is not ready yet. Store this URL for future use.
-  nsCOMPtr<nsIURI> ucsURL = DeserializeURI(userContentSheetURL);
-  nsLayoutStylesheetCache::SetUserContentCSSURL(ucsURL);
-
   // This will register cross-process observer.
   mozilla::dom::time::InitializeDateCacheCleaner();
 }
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index dd9f8644ffa3..d068e1e16fb1 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -195,8 +195,6 @@
 
 #include "nsIBidiKeyboard.h"
 
-#include "nsLayoutStylesheetCache.h"
-
 #ifdef MOZ_WEBRTC
 #include "signaling/src/peerconnection/WebrtcGlobalParent.h"
 #endif
@@ -2977,8 +2975,7 @@ ContentParent::RecvGetXPCOMProcessAttributes(bool* aIsOffline,
                                              InfallibleTArray<nsString>* dictionaries,
                                              ClipboardCapabilities* clipboardCaps,
                                              DomainPolicyClone* domainPolicy,
-                                             StructuredCloneData* aInitialData,
-                                             OptionalURIParams* aUserContentCSSURL)
+                                             StructuredCloneData* aInitialData)
 {
   nsCOMPtr<nsIIOService> io(do_GetIOService());
   MOZ_ASSERT(io, "No IO service?");
@@ -3035,16 +3032,6 @@ ContentParent::RecvGetXPCOMProcessAttributes(bool* aIsOffline,
     }
   }
 
-  // XXX bug 1046166
-  // Content processes have no permission to read profile, so we send the
-  // file URL instead.
-  StyleSheetHandle::RefPtr ucs = nsLayoutStylesheetCache::For(StyleBackendType::Gecko)->UserContentSheet();
-  if (ucs) {
-    SerializeURI(ucs->GetSheetURI(), *aUserContentCSSURL);
-  } else {
-    SerializeURI(nullptr, *aUserContentCSSURL);
-  }
-
   return true;
 }
 
diff --git a/dom/ipc/ContentParent.h b/dom/ipc/ContentParent.h
index f31ee58e2e92..523ae9ed01aa 100644
--- a/dom/ipc/ContentParent.h
+++ b/dom/ipc/ContentParent.h
@@ -732,8 +732,7 @@ private:
                                 InfallibleTArray<nsString>* dictionaries,
                                 ClipboardCapabilities* clipboardCaps,
                                 DomainPolicyClone* domainPolicy,
-                                StructuredCloneData* initialData,
-                                OptionalURIParams* aUserContentSheetURL) override;
+                                StructuredCloneData* initialData) override;
 
   virtual bool
   DeallocPJavaScriptParent(mozilla::jsipc::PJavaScriptParent*) override;
diff --git a/dom/ipc/PContent.ipdl b/dom/ipc/PContent.ipdl
index 01d486ae269a..e82a2d2a076c 100644
--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -722,8 +722,7 @@ parent:
                  bool haveBidiKeyboards, nsString[] dictionaries,
                  ClipboardCapabilities clipboardCaps,
                  DomainPolicyClone domainPolicy,
-                 StructuredCloneData initialData,
-                 OptionalURIParams userContentSheetURL);
+                 StructuredCloneData initialData);
 
     sync CreateChildProcess(IPCTabContext context,
                             ProcessPriority priority,
diff --git a/layout/style/nsLayoutStylesheetCache.cpp b/layout/style/nsLayoutStylesheetCache.cpp
index 87f4bf570ae5..298ccf08f033 100644
--- a/layout/style/nsLayoutStylesheetCache.cpp
+++ b/layout/style/nsLayoutStylesheetCache.cpp
@@ -21,7 +21,6 @@
 #include "nsServiceManagerUtils.h"
 #include "nsIXULRuntime.h"
 #include "nsPrintfCString.h"
-#include "nsXULAppAPI.h"
 
 // Includes for the crash report annotation in ErrorLoadingBuiltinSheet.
 #ifdef MOZ_CRASHREPORTER
@@ -255,14 +254,6 @@ nsLayoutStylesheetCache::Shutdown()
   gCSSLoader_Servo = nullptr;
   gStyleCache_Gecko = nullptr;
   gStyleCache_Servo = nullptr;
-  MOZ_ASSERT(!gUserContentSheetURL, "Got the URL but never used?");
-}
-
-void
-nsLayoutStylesheetCache::SetUserContentCSSURL(nsIURI* aURI)
-{
-  MOZ_ASSERT(XRE_IsContentProcess(), "Only used in content processes.");
-  gUserContentSheetURL = aURI;
 }
 
 MOZ_DEFINE_MALLOC_SIZE_OF(LayoutStylesheetCacheMallocSizeOf)
@@ -342,12 +333,6 @@ nsLayoutStylesheetCache::nsLayoutStylesheetCache(StyleBackendType aType)
   LoadSheetURL("chrome://global/content/xul.css",
                &mXULSheet, eAgentSheetFeatures);
 
-  if (gUserContentSheetURL) {
-    MOZ_ASSERT(XRE_IsContentProcess(), "Only used in content processes.");
-    LoadSheet(gUserContentSheetURL, &mUserContentSheet, eUserSheetFeatures);
-    gUserContentSheetURL = nullptr;
-  }
-
   // The remaining sheets are created on-demand do to their use being rarer
   // (which helps save memory for Firefox OS apps) or because they need to
   // be re-loadable in DependentPrefChanged.
@@ -982,6 +967,3 @@ nsLayoutStylesheetCache::gCSSLoader_Gecko;
 
 mozilla::StaticRefPtr<mozilla::css::Loader>
 nsLayoutStylesheetCache::gCSSLoader_Servo;
-
-mozilla::StaticRefPtr<nsIURI>
-nsLayoutStylesheetCache::gUserContentSheetURL;
diff --git a/layout/style/nsLayoutStylesheetCache.h b/layout/style/nsLayoutStylesheetCache.h
index b3aabf3628e0..996497937c0b 100644
--- a/layout/style/nsLayoutStylesheetCache.h
+++ b/layout/style/nsLayoutStylesheetCache.h
@@ -66,8 +66,6 @@ class nsLayoutStylesheetCache final
 
   static void Shutdown();
 
-  static void SetUserContentCSSURL(nsIURI* aURI);
-
   size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
 
 private:
@@ -94,7 +92,6 @@ private:
   static mozilla::StaticRefPtr<nsLayoutStylesheetCache> gStyleCache_Servo;
   static mozilla::StaticRefPtr<mozilla::css::Loader> gCSSLoader_Gecko;
   static mozilla::StaticRefPtr<mozilla::css::Loader> gCSSLoader_Servo;
-  static mozilla::StaticRefPtr<nsIURI> gUserContentSheetURL;
   mozilla::StyleBackendType mBackendType;
   mozilla::StyleSheetHandle::RefPtr mChromePreferenceSheet;
   mozilla::StyleSheetHandle::RefPtr mContentEditableSheet;