--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -1583,17 +1583,17 @@ nsDocument::nsDocument(const char* aCont
   // void state used to differentiate an empty source from an unselected source
   mPreloadPictureFoundSource.SetIsVoid(true);
   // For determining if this is a flash document which should be
   // blocked based on its principal.
   mPrincipalFlashClassifier = new PrincipalFlashClassifier();
 }
 
 void
-nsDocument::ClearAllBoxObjects()
+nsIDocument::ClearAllBoxObjects()
 {
   if (mBoxObjectTable) {
     for (auto iter = mBoxObjectTable->Iter(); !iter.Done(); iter.Next()) {
       nsPIBoxObject* boxObject = iter.UserData();
       if (boxObject) {
         boxObject->Clear();
       }
     }
@@ -2936,17 +2936,17 @@ nsIDocument::ApplySettingsFromCSP(bool a
     if (!mUpgradeInsecurePreloads) {
       rv = preloadCsp->GetUpgradeInsecureRequests(&mUpgradeInsecurePreloads);
       NS_ENSURE_SUCCESS_VOID(rv);
     }
   }
 }
 
 nsresult
-nsDocument::InitCSP(nsIChannel* aChannel)
+nsIDocument::InitCSP(nsIChannel* aChannel)
 {
   MOZ_ASSERT(!mScriptGlobalObject,
              "CSP must be initialized before mScriptGlobalObject is set!");
   if (!CSPService::sCSPEnabled) {
     MOZ_LOG(gCspPRLog, LogLevel::Debug,
            ("CSP is disabled, skipping CSP init for document %p", this));
     return NS_OK;
   }
@@ -3004,17 +3004,17 @@ nsDocument::InitCSP(nsIChannel* aChannel
     }
 
     return NS_OK;
   }
 
   MOZ_LOG(gCspPRLog, LogLevel::Debug, ("Document is an add-on or CSP header specified %p", this));
 
   nsCOMPtr<nsIContentSecurityPolicy> csp;
-  rv = principal->EnsureCSP(this, getter_AddRefs(csp));
+  rv = principal->EnsureCSP(static_cast<nsDocument*>(this), getter_AddRefs(csp));
   NS_ENSURE_SUCCESS(rv, rv);
 
   // ----- if the doc is an addon, apply its CSP.
   if (addonPolicy) {
     nsCOMPtr<nsIAddonPolicyService> aps = do_GetService("@mozilla.org/addons/policy-service;1");
 
     nsAutoString addonCSP;
     Unused << ExtensionPolicyService::GetSingleton().GetBaseCSP(addonCSP);
@@ -8463,46 +8463,46 @@ nsDocument::UnblockOnload(bool aFireSync
                                  false);
       asyncDispatcher->PostDOMEvent();
     }
   }
 }
 
 class nsUnblockOnloadEvent : public Runnable {
 public:
-  explicit nsUnblockOnloadEvent(nsDocument* aDoc)
+  explicit nsUnblockOnloadEvent(nsIDocument* aDoc)
     : mozilla::Runnable("nsUnblockOnloadEvent")
     , mDoc(aDoc)
   {
   }
   NS_IMETHOD Run() override {
     mDoc->DoUnblockOnload();
     return NS_OK;
   }
 private:
-  RefPtr<nsDocument> mDoc;
+  RefPtr<nsIDocument> mDoc;
 };
 
 void
-nsDocument::PostUnblockOnloadEvent()
+nsIDocument::PostUnblockOnloadEvent()
 {
   MOZ_RELEASE_ASSERT(NS_IsMainThread());
   nsCOMPtr<nsIRunnable> evt = new nsUnblockOnloadEvent(this);
   nsresult rv =
     Dispatch(TaskCategory::Other, evt.forget());
   if (NS_SUCCEEDED(rv)) {
     // Stabilize block count so we don't post more events while this one is up
     ++mOnloadBlockCount;
   } else {
     NS_WARNING("failed to dispatch nsUnblockOnloadEvent");
   }
 }
 
 void
-nsDocument::DoUnblockOnload()
+nsIDocument::DoUnblockOnload()
 {
   NS_PRECONDITION(!mDisplayDocument,
                   "Shouldn't get here for resource document");
   NS_PRECONDITION(mOnloadBlockCount != 0,
                   "Shouldn't have a count of zero here, since we stabilized in "
                   "PostUnblockOnloadEvent");
 
   --mOnloadBlockCount;

--- a/dom/base/nsDocument.h
+++ b/dom/base/nsDocument.h
@@ -68,17 +68,16 @@
 
 
 class nsDOMStyleSheetSetList;
 class nsDocument;
 class nsIRadioVisitor;
 class nsIFormControl;
 struct nsRadioGroupStruct;
 class nsOnloadBlocker;
-class nsUnblockOnloadEvent;
 class nsDOMNavigationTiming;
 class nsWindowSizes;
 class nsHtml5TreeOpExecutor;
 class nsDocumentOnStack;
 class nsISecurityConsoleMessage;
 
 namespace mozilla {
 class EventChainPreVisitor;
@@ -307,23 +306,16 @@ public:
   // The application cache that this document is associated with, if
   // any.  This can change during the lifetime of the document.
   nsCOMPtr<nsIApplicationCache> mApplicationCache;
 
   nsCOMPtr<nsIContent> mFirstBaseNodeWithHref;
 private:
   friend class nsUnblockOnloadEvent;
 
-  void PostUnblockOnloadEvent();
-  void DoUnblockOnload();
-
-  nsresult InitCSP(nsIChannel* aChannel);
-
-  void ClearAllBoxObjects();
-
   // These are not implemented and not supported.
   nsDocument(const nsDocument& aOther);
   nsDocument& operator=(const nsDocument& aOther);
 };
 
 class nsDocumentOnStack
 {
 public:

--- a/dom/base/nsIDocument.h
+++ b/dom/base/nsIDocument.h
@@ -111,16 +111,17 @@ class nsIStructuredCloneContainer;
 class nsIURI;
 class nsIVariant;
 class nsViewManager;
 class nsPresContext;
 class nsRange;
 class nsSMILAnimationController;
 class nsSVGElement;
 class nsTextNode;
+class nsUnblockOnloadEvent;
 class nsWindowSizes;
 class nsDOMCaretPosition;
 class nsViewportInfo;
 class nsIGlobalObject;
 struct nsCSSSelectorList;
 
 namespace mozilla {
 class AbstractThread;
@@ -1432,16 +1433,26 @@ public:
   //
   // This array contains nodes that have been blocked to prevent
   // user tracking. They most likely have had their nsIChannel
   // canceled by the URL classifier (Safebrowsing).
   //
   already_AddRefed<nsSimpleContentList> BlockedTrackingNodes() const;
 
 protected:
+  friend class nsUnblockOnloadEvent;
+
+  nsresult InitCSP(nsIChannel* aChannel);
+
+  void PostUnblockOnloadEvent();
+
+  void DoUnblockOnload();
+
+  void ClearAllBoxObjects();
+
   void MaybeEndOutermostXBLUpdate();
 
   void DispatchContentLoadedEvents();
 
   void DispatchPageTransition(mozilla::dom::EventTarget* aDispatchTarget,
                               const nsAString& aType,
                               bool aPersisted);