Bug 1571066: Return WindowProxyHolder from nsDocShell::GetWindowProxy. r=peterv

Returning BrowsingContext* from these sorts of getters tends to lead to
misuse. WindowProxyHolder is the semantically correct type to return here, in
any case.

Differential Revision: https://phabricator.services.mozilla.com/D52096

--HG--
extra : moz-landing-system : lando

docshell/base/nsDocShell.h

@@ -21,6 +21,7 @@
 #include "mozilla/dom/ProfileTimelineMarkerBinding.h"
 #include "mozilla/gfx/Matrix.h"
 #include "mozilla/dom/ChildSHistory.h"
+#include "mozilla/dom/WindowProxyHolder.h"
 
 #include "nsIAuthPromptProvider.h"
 #include "nsIBaseWindow.h"
@@ -448,9 +449,9 @@ class nsDocShell final : public nsDocLoader,
   // shift while triggering reload)
   bool IsForceReloading();
 
-  mozilla::dom::BrowsingContext* GetWindowProxy() {
+  mozilla::dom::WindowProxyHolder GetWindowProxy() {
     EnsureScriptEnvironment();
-    return mBrowsingContext;
+    return mozilla::dom::WindowProxyHolder(mBrowsingContext);
   }
 
   /**

dom/xul/XULFrameElement.cpp

@@ -52,7 +52,7 @@ already_AddRefed<nsIWebNavigation> XULFrameElement::GetWebNavigation() {
 Nullable<WindowProxyHolder> XULFrameElement::GetContentWindow() {
   RefPtr<nsDocShell> docShell = GetDocShell();
   if (docShell) {
-    return WindowProxyHolder(docShell->GetWindowProxy());
+    return docShell->GetWindowProxy();
   }
 
   return nullptr;