diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index 48165ce31758..dc642a903526 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -3551,9 +3551,8 @@ nsGlobalWindow::DetachFromDocShell()
     inner->FreeInnerObjects();
   }
 
-  if (auto* reporter = nsWindowMemoryReporter::Get()) {
-    reporter->ObserveDOMWindowDetached(this);
-  }
+  // Don't report that we were detached to the nsWindowMemoryReporter, as it
+  // only tracks inner windows.
 
   NotifyWindowIDDestroyed("outer-window-destroyed");
 
diff --git a/dom/base/nsWindowMemoryReporter.cpp b/dom/base/nsWindowMemoryReporter.cpp
index 0978f49d78ed..693dba09d626 100644
--- a/dom/base/nsWindowMemoryReporter.cpp
+++ b/dom/base/nsWindowMemoryReporter.cpp
@@ -49,7 +49,7 @@ NS_IMPL_ISUPPORTS(nsWindowMemoryReporter, nsIMemoryReporter, nsIObserver,
                   nsISupportsWeakReference)
 
 static nsresult
-AddNonJSSizeOfWindowAndItsDescendents(nsGlobalWindow* aWindow,
+AddNonJSSizeOfWindowAndItsDescendents(nsGlobalWindowOuter* aWindow,
                                       nsTabSizes* aSizes)
 {
   // Measure the window.
@@ -58,8 +58,7 @@ AddNonJSSizeOfWindowAndItsDescendents(nsGlobalWindow* aWindow,
   aWindow->AddSizeOfIncludingThis(windowSizes);
 
   // Measure the inner window, if there is one.
-  nsGlobalWindow* inner = aWindow->IsOuterWindow() ? aWindow->GetCurrentInnerWindowInternal()
-                                                   : nullptr;
+  nsGlobalWindowInner* inner = aWindow->GetCurrentInnerWindowInternal();
   if (inner) {
     inner->AddSizeOfIncludingThis(windowSizes);
   }
@@ -79,7 +78,7 @@ AddNonJSSizeOfWindowAndItsDescendents(nsGlobalWindow* aWindow,
       NS_ENSURE_SUCCESS(rv, rv);
       NS_ENSURE_STATE(child);
 
-      nsGlobalWindow* childWin = nsGlobalWindow::Cast(child);
+      nsGlobalWindowOuter* childWin = nsGlobalWindowOuter::Cast(child);
 
       rv = AddNonJSSizeOfWindowAndItsDescendents(childWin, aSizes);
       NS_ENSURE_SUCCESS(rv, rv);
@@ -131,7 +130,7 @@ nsWindowMemoryReporter::Get()
 }
 
 static already_AddRefed<nsIURI>
-GetWindowURI(nsGlobalWindow* aWindow)
+GetWindowURI(nsGlobalWindowInner* aWindow)
 {
   NS_ENSURE_TRUE(aWindow, nullptr);
 
@@ -162,8 +161,16 @@ GetWindowURI(nsGlobalWindow* aWindow)
   return uri.forget();
 }
 
+// Forward to the inner window if we need to when getting the window's URI.
+static already_AddRefed<nsIURI>
+GetWindowURI(nsGlobalWindowOuter* aWindow)
+{
+  NS_ENSURE_TRUE(aWindow, nullptr);
+  return GetWindowURI(aWindow->GetCurrentInnerWindowInternal());
+}
+
 static void
-AppendWindowURI(nsGlobalWindow *aWindow, nsACString& aStr, bool aAnonymize)
+AppendWindowURI(nsGlobalWindowInner *aWindow, nsACString& aStr, bool aAnonymize)
 {
   nsCOMPtr<nsIURI> uri = GetWindowURI(aWindow);
 
@@ -233,7 +240,7 @@ ReportCount(const nsCString& aBasePath, const char* aPathTail,
 }
 
 static void
-CollectWindowReports(nsGlobalWindow *aWindow,
+CollectWindowReports(nsGlobalWindowInner *aWindow,
                      amIAddonManager *addonManager,
                      nsWindowSizes *aWindowTotalSizes,
                      nsTHashtable<nsUint64HashKey> *aGhostWindowIDs,
@@ -247,7 +254,7 @@ CollectWindowReports(nsGlobalWindow *aWindow,
 
   // Avoid calling aWindow->GetTop() if there's no outer window.  It will work
   // just fine, but will spew a lot of warnings.
-  nsGlobalWindow *top = nullptr;
+  nsGlobalWindowOuter *top = nullptr;
   nsCOMPtr<nsIURI> location;
   if (aWindow->GetOuterWindow()) {
     // Our window should have a null top iff it has a null docshell.
@@ -276,7 +283,7 @@ CollectWindowReports(nsGlobalWindow *aWindow,
 
   if (top) {
     windowPath += NS_LITERAL_CSTRING("top(");
-    AppendWindowURI(top, windowPath, aAnonymize);
+    AppendWindowURI(top->GetCurrentInnerWindowInternal(), windowPath, aAnonymize);
     windowPath.AppendPrintf(", id=%" PRIu64 ")", top->WindowID());
 
     aTopWindowPaths->Put(aWindow->WindowID(), windowPath);
@@ -538,14 +545,14 @@ CollectWindowReports(nsGlobalWindow *aWindow,
 #undef REPORT_COUNT
 }
 
-typedef nsTArray< RefPtr<nsGlobalWindow> > WindowArray;
+typedef nsTArray< RefPtr<nsGlobalWindowInner> > WindowArray;
 
 NS_IMETHODIMP
 nsWindowMemoryReporter::CollectReports(nsIHandleReportCallback* aHandleReport,
                                        nsISupports* aData, bool aAnonymize)
 {
-  nsGlobalWindow::WindowByIdTable* windowsById =
-    nsGlobalWindow::GetWindowsTable();
+  nsGlobalWindowInner::InnerWindowByIdTable* windowsById =
+    nsGlobalWindowInner::GetWindowsTable();
   NS_ENSURE_TRUE(windowsById, NS_OK);
 
   // Hold on to every window in memory so that window objects can't be
@@ -560,14 +567,14 @@ nsWindowMemoryReporter::CollectReports(nsIHandleReportCallback* aHandleReport,
   nsTHashtable<nsUint64HashKey> ghostWindows;
   CheckForGhostWindows(&ghostWindows);
   for (auto iter = ghostWindows.ConstIter(); !iter.Done(); iter.Next()) {
-    nsGlobalWindow::WindowByIdTable* windowsById =
-      nsGlobalWindow::GetWindowsTable();
+    nsGlobalWindowInner::InnerWindowByIdTable* windowsById =
+      nsGlobalWindowInner::GetWindowsTable();
     if (!windowsById) {
       NS_WARNING("Couldn't get window-by-id hashtable?");
       continue;
     }
 
-    nsGlobalWindow* window = windowsById->Get(iter.Get()->GetKey());
+    nsGlobalWindowInner* window = windowsById->Get(iter.Get()->GetKey());
     if (!window) {
       NS_WARNING("Could not look up window?");
       continue;
@@ -784,7 +791,7 @@ nsWindowMemoryReporter::Observe(nsISupports *aSubject, const char *aTopic,
 }
 
 void
-nsWindowMemoryReporter::ObserveDOMWindowDetached(nsGlobalWindow* aWindow)
+nsWindowMemoryReporter::ObserveDOMWindowDetached(nsGlobalWindowInner* aWindow)
 {
   nsWeakPtr weakWindow = do_GetWeakReference(static_cast<nsIDOMEventTarget*>(aWindow));
   if (!weakWindow) {
@@ -881,8 +888,8 @@ nsWindowMemoryReporter::CheckForGhostWindows(
     return;
   }
 
-  nsGlobalWindow::WindowByIdTable *windowsById =
-    nsGlobalWindow::GetWindowsTable();
+  nsGlobalWindowInner::InnerWindowByIdTable *windowsById =
+    nsGlobalWindowInner::GetWindowsTable();
   if (!windowsById) {
     NS_WARNING("GetWindowsTable returned null");
     return;
@@ -898,7 +905,7 @@ nsWindowMemoryReporter::CheckForGhostWindows(
   for (auto iter = windowsById->Iter(); !iter.Done(); iter.Next()) {
     // Null outer window implies null top, but calling GetTop() when there's no
     // outer window causes us to spew debug warnings.
-    nsGlobalWindow* window = iter.UserData();
+    nsGlobalWindowInner* window = iter.UserData();
     if (!window->GetOuterWindow() || !window->GetTopInternal()) {
       // This window is detached, so we don't care about its domain.
       continue;
@@ -948,7 +955,7 @@ nsWindowMemoryReporter::CheckForGhostWindows(
       continue;
     }
 
-    nsCOMPtr<nsIURI> uri = GetWindowURI(nsGlobalWindow::Cast(window));
+    nsCOMPtr<nsIURI> uri = GetWindowURI(nsGlobalWindowInner::Cast(window));
 
     nsAutoCString domain;
     if (uri) {
@@ -1004,8 +1011,8 @@ nsWindowMemoryReporter::UnlinkGhostWindows()
     return;
   }
 
-  nsGlobalWindow::WindowByIdTable* windowsById =
-    nsGlobalWindow::GetWindowsTable();
+  nsGlobalWindowInner::InnerWindowByIdTable* windowsById =
+    nsGlobalWindowInner::GetWindowsTable();
   if (!windowsById) {
     return;
   }
@@ -1021,13 +1028,13 @@ nsWindowMemoryReporter::UnlinkGhostWindows()
   nsTHashtable<nsUint64HashKey> ghostWindows;
   sWindowReporter->CheckForGhostWindows(&ghostWindows);
   for (auto iter = ghostWindows.ConstIter(); !iter.Done(); iter.Next()) {
-    nsGlobalWindow::WindowByIdTable* windowsById =
-      nsGlobalWindow::GetWindowsTable();
+    nsGlobalWindowInner::InnerWindowByIdTable* windowsById =
+      nsGlobalWindowInner::GetWindowsTable();
     if (!windowsById) {
       continue;
     }
 
-    RefPtr<nsGlobalWindow> window = windowsById->Get(iter.Get()->GetKey());
+    RefPtr<nsGlobalWindowInner> window = windowsById->Get(iter.Get()->GetKey());
     if (window) {
       window->RiskyUnlink();
     }
diff --git a/dom/base/nsWindowMemoryReporter.h b/dom/base/nsWindowMemoryReporter.h
index 7e7df370fe5e..4c3d0c992458 100644
--- a/dom/base/nsWindowMemoryReporter.h
+++ b/dom/base/nsWindowMemoryReporter.h
@@ -101,7 +101,7 @@ public:
 #endif
 
   static nsWindowMemoryReporter* Get();
-  void ObserveDOMWindowDetached(nsGlobalWindow* aWindow);
+  void ObserveDOMWindowDetached(nsGlobalWindowInner* aWindow);
 
   static int64_t GhostWindowsDistinguishedAmount();