diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index e7a2e346c99b..ae9221bdeabd 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -1468,11 +1468,11 @@ PresShell* nsDocShell::GetEldestPresShell() {
 }
 
 NS_IMETHODIMP
-nsDocShell::GetContentViewer(nsIDocumentViewer** aContentViewer) {
-  NS_ENSURE_ARG_POINTER(aContentViewer);
+nsDocShell::GetContentViewer(nsIDocumentViewer** aDocumentViewer) {
+  NS_ENSURE_ARG_POINTER(aDocumentViewer);
 
-  *aContentViewer = mDocumentViewer;
-  NS_IF_ADDREF(*aContentViewer);
+  *aDocumentViewer = mDocumentViewer;
+  NS_IF_ADDREF(*aDocumentViewer);
   return NS_OK;
 }
 
@@ -5592,7 +5592,7 @@ static bool IsFollowupPartOfMultipart(nsIRequest* aRequest) {
          !firstPart;
 }
 
-nsresult nsDocShell::Embed(nsIDocumentViewer* aContentViewer,
+nsresult nsDocShell::Embed(nsIDocumentViewer* aDocumentViewer,
                            WindowGlobalChild* aWindowActor,
                            bool aIsTransientAboutBlank, bool aPersist,
                            nsIRequest* aRequest, nsIURI* aPreviousURI) {
@@ -5600,7 +5600,7 @@ nsresult nsDocShell::Embed(nsIDocumentViewer* aContentViewer,
   // setting up new document
   PersistLayoutHistoryState();
 
-  nsresult rv = SetupNewViewer(aContentViewer, aWindowActor);
+  nsresult rv = SetupNewViewer(aDocumentViewer, aWindowActor);
   NS_ENSURE_SUCCESS(rv, rv);
 
   // XXX What if SetupNewViewer fails?
@@ -7046,15 +7046,15 @@ nsDocShell::RestorePresentationEvent::Run() {
 }
 
 NS_IMETHODIMP
-nsDocShell::BeginRestore(nsIDocumentViewer* aContentViewer, bool aTop) {
+nsDocShell::BeginRestore(nsIDocumentViewer* aDocumentViewer, bool aTop) {
   MOZ_ASSERT(!mozilla::SessionHistoryInParent());
 
   nsresult rv;
-  if (!aContentViewer) {
+  if (!aDocumentViewer) {
     rv = EnsureDocumentViewer();
     NS_ENSURE_SUCCESS(rv, rv);
 
-    aContentViewer = mDocumentViewer;
+    aDocumentViewer = mDocumentViewer;
   }
 
   // Dispatch events for restoring the presentation.  We try to simulate
@@ -7062,7 +7062,7 @@ nsDocShell::BeginRestore(nsIDocumentViewer* aContentViewer, bool aTop) {
   // the document's channel to the loadgroup to initiate stateChange
   // notifications.
 
-  RefPtr<Document> doc = aContentViewer->GetDocument();
+  RefPtr<Document> doc = aDocumentViewer->GetDocument();
   if (doc) {
     nsIChannel* channel = doc->GetChannel();
     if (channel) {
diff --git a/docshell/base/nsDocShell.h b/docshell/base/nsDocShell.h
index aa2b49f680d1..45198e97454b 100644
--- a/docshell/base/nsDocShell.h
+++ b/docshell/base/nsDocShell.h
@@ -985,7 +985,7 @@ class nsDocShell final : public nsDocLoader,
   nsresult EnsureCommandHandler();
   nsresult RefreshURIFromQueue();
   void RefreshURIToQueue();
-  nsresult Embed(nsIDocumentViewer* aContentViewer,
+  nsresult Embed(nsIDocumentViewer* aDocumentViewer,
                  mozilla::dom::WindowGlobalChild* aWindowActor,
                  bool aIsTransientAboutBlank, bool aPersist,
                  nsIRequest* aRequest, nsIURI* aPreviousURI);
diff --git a/docshell/shistory/SessionHistoryEntry.cpp b/docshell/shistory/SessionHistoryEntry.cpp
index 1f295582d1d2..818549d1bde5 100644
--- a/docshell/shistory/SessionHistoryEntry.cpp
+++ b/docshell/shistory/SessionHistoryEntry.cpp
@@ -654,13 +654,13 @@ SessionHistoryEntry::SetReferrerInfo(nsIReferrerInfo* aReferrerInfo) {
 }
 
 NS_IMETHODIMP
-SessionHistoryEntry::GetContentViewer(nsIDocumentViewer** aContentViewer) {
-  *aContentViewer = nullptr;
+SessionHistoryEntry::GetContentViewer(nsIDocumentViewer** aDocumentViewer) {
+  *aDocumentViewer = nullptr;
   return NS_OK;
 }
 
 NS_IMETHODIMP
-SessionHistoryEntry::SetContentViewer(nsIDocumentViewer* aContentViewer) {
+SessionHistoryEntry::SetContentViewer(nsIDocumentViewer* aDocumentViewer) {
   MOZ_CRASH("This lives in the child process");
   return NS_ERROR_FAILURE;
 }
diff --git a/layout/build/nsContentDLF.cpp b/layout/build/nsContentDLF.cpp
index 83cb7466dd28..60375d8e5657 100644
--- a/layout/build/nsContentDLF.cpp
+++ b/layout/build/nsContentDLF.cpp
@@ -200,14 +200,14 @@ NS_IMETHODIMP
 nsContentDLF::CreateInstanceForDocument(nsISupports* aContainer,
                                         Document* aDocument,
                                         const char* aCommand,
-                                        nsIDocumentViewer** aContentViewer) {
+                                        nsIDocumentViewer** aDocumentViewer) {
   MOZ_ASSERT(aDocument);
 
   nsCOMPtr<nsIDocumentViewer> viewer = NS_NewDocumentViewer();
 
   // Bind the document to the Content Viewer
   viewer->LoadStart(aDocument);
-  viewer.forget(aContentViewer);
+  viewer.forget(aDocumentViewer);
   return NS_OK;
 }
 
@@ -288,7 +288,7 @@ already_AddRefed<Document> nsContentDLF::CreateBlankDocument(
 nsresult nsContentDLF::CreateDocument(
     const char* aCommand, nsIChannel* aChannel, nsILoadGroup* aLoadGroup,
     nsIDocShell* aContainer, nsContentDLF::DocumentCreator aDocumentCreator,
-    nsIStreamListener** aDocListener, nsIDocumentViewer** aContentViewer) {
+    nsIStreamListener** aDocListener, nsIDocumentViewer** aDocumentViewer) {
   MOZ_ASSERT(aDocumentCreator);
 
   nsresult rv = NS_ERROR_FAILURE;
@@ -324,7 +324,7 @@ nsresult nsContentDLF::CreateDocument(
 
   // Bind the document to the Content Viewer
   viewer->LoadStart(doc);
-  viewer.forget(aContentViewer);
+  viewer.forget(aDocumentViewer);
   return NS_OK;
 }
 
diff --git a/layout/build/nsContentDLF.h b/layout/build/nsContentDLF.h
index 2c8b6dab4fdb..b16ec7550368 100644
--- a/layout/build/nsContentDLF.h
+++ b/layout/build/nsContentDLF.h
@@ -37,7 +37,7 @@ class nsContentDLF final : public nsIDocumentLoaderFactory {
                           nsILoadGroup* aLoadGroup, nsIDocShell* aContainer,
                           DocumentCreator aDocumentCreator,
                           nsIStreamListener** aDocListener,
-                          nsIDocumentViewer** aContentViewer);
+                          nsIDocumentViewer** aDocumentViewer);
 
   /**
    * Create a blank document using the given loadgroup and given