Bug 1662975 - Don't return from window.print() until the print dialog is closed. r=jwatt

As much as I hate nested event loops, I think we need to do it for this
case :)

Hopefully print() already assumes nested event loops can happen because
of the native dialog so it's already properly set up for this.

Differential Revision: https://phabricator.services.mozilla.com/D89254

dom/base/nsFrameLoader.cpp

@@ -3286,7 +3286,8 @@ already_AddRefed<Promise> nsFrameLoader::PrintPreview(
   sourceWindow->Print(
       aPrintSettings,
       /* aListener = */ nullptr, docShellToCloneInto,
-      /* aIsPreview = */ true,
+      nsGlobalWindowOuter::IsPreview::Yes,
+      nsGlobalWindowOuter::BlockUntilDone::No,
       [resolve](const PrintPreviewResultInfo& aInfo) { resolve(aInfo); }, rv);
   if (NS_WARN_IF(rv.Failed())) {
     promise->MaybeReject(std::move(rv));
@@ -3357,7 +3358,8 @@ already_AddRefed<Promise> nsFrameLoader::Print(uint64_t aOuterWindowID,
   ErrorResult rv;
   outerWindow->Print(aPrintSettings, listener,
                      /* aDocShellToCloneInto = */ nullptr,
-                     /* aIsPreview = */ false,
+                     nsGlobalWindowOuter::IsPreview::No,
+                     nsGlobalWindowOuter::BlockUntilDone::No,
                      /* aPrintPreviewCallback = */ nullptr, rv);
   if (rv.Failed()) {
     promise->MaybeReject(std::move(rv));

dom/base/nsGlobalWindowInner.cpp

@@ -3613,7 +3613,8 @@ Nullable<WindowProxyHolder> nsGlobalWindowInner::PrintPreview(
     nsIDocShell* aDocShellToCloneInto, ErrorResult& aError) {
   FORWARD_TO_OUTER_OR_THROW(Print,
                             (aSettings, aListener, aDocShellToCloneInto,
-                             /* aIsPreview = */ true,
+                             nsGlobalWindowOuter::IsPreview::Yes,
+                             nsGlobalWindowOuter::BlockUntilDone::No,
                              /* aPrintPreviewCallback = */ nullptr, aError),
                             aError, nullptr);
 }

dom/base/nsGlobalWindowOuter.cpp

@@ -5274,13 +5274,15 @@ void nsGlobalWindowOuter::PrintOuter(ErrorResult& aError) {
     settings->SetShowPrintProgress(false);
   }
 
-  Print(settings, nullptr, nullptr, isPreview, nullptr, aError);
+  Print(settings, nullptr, nullptr, IsPreview(isPreview),
+        BlockUntilDone(isPreview), nullptr, aError);
 #endif
 }
 
 Nullable<WindowProxyHolder> nsGlobalWindowOuter::Print(
     nsIPrintSettings* aPrintSettings, nsIWebProgressListener* aListener,
-    nsIDocShell* aDocShellToCloneInto, bool aIsPreview,
+    nsIDocShell* aDocShellToCloneInto, IsPreview aIsPreview,
+    BlockUntilDone aBlockUntilDone,
     PrintPreviewResolver&& aPrintPreviewCallback, ErrorResult& aError) {
 #ifdef NS_PRINTING
   nsCOMPtr<nsIPrintSettingsService> printSettingsService =
@@ -5310,7 +5312,7 @@ Nullable<WindowProxyHolder> nsGlobalWindowOuter::Print(
 
   nsCOMPtr<nsIContentViewer> cv;
   RefPtr<BrowsingContext> bc;
-  if (docToPrint->IsStaticDocument() && aIsPreview) {
+  if (docToPrint->IsStaticDocument() && bool(aIsPreview)) {
     // We're already a print preview window, just reuse our browsing context /
     // content viewer.
     //
@@ -5337,7 +5339,8 @@ Nullable<WindowProxyHolder> nsGlobalWindowOuter::Print(
       bc = aDocShellToCloneInto->GetBrowsingContext();
     } else {
       AutoNoJSAPI nojsapi;
-      auto printKind = aIsPreview ? PrintKind::PrintPreview : PrintKind::Print;
+      auto printKind =
+          bool(aIsPreview) ? PrintKind::PrintPreview : PrintKind::Print;
       aError = OpenInternal(EmptyString(), EmptyString(), EmptyString(),
                             false,             // aDialog
                             false,             // aContentModal
@@ -5438,13 +5441,22 @@ Nullable<WindowProxyHolder> nsGlobalWindowOuter::Print(
     return nullptr;
   }
 
-  if (aIsPreview) {
+  if (bool(aIsPreview)) {
     aError = webBrowserPrint->PrintPreview(aPrintSettings, aListener,
                                            std::move(aPrintPreviewCallback));
+    if (aError.Failed()) {
+      return nullptr;
+    }
   } else {
     // Historically we've eaten this error.
     webBrowserPrint->Print(aPrintSettings, aListener);
   }
+
+  if (bool(aBlockUntilDone)) {
+    // Wait until print document is closed.
+    SpinEventLoopUntil([&] { return bc->IsDiscarded(); });
+  }
+
   return WindowProxyHolder(std::move(bc));
 #else
   return nullptr;

dom/base/nsGlobalWindowOuter.h

@@ -586,9 +586,11 @@ class nsGlobalWindowOuter final : public mozilla::dom::EventTarget,
 
   void PrintOuter(mozilla::ErrorResult& aError);
 
+  enum class IsPreview : bool { No, Yes };
+  enum class BlockUntilDone : bool { No, Yes };
   mozilla::dom::Nullable<mozilla::dom::WindowProxyHolder> Print(
-      nsIPrintSettings*, nsIWebProgressListener*, nsIDocShell*, bool aIsPreview,
-      PrintPreviewResolver&& aPrintPreviewCallback, mozilla::ErrorResult&);
+      nsIPrintSettings*, nsIWebProgressListener*, nsIDocShell*, IsPreview,
+      BlockUntilDone, PrintPreviewResolver&&, mozilla::ErrorResult&);
   mozilla::dom::Selection* GetSelectionOuter();
   already_AddRefed<mozilla::dom::Selection> GetSelection() override;
   nsScreen* GetScreen();

dom/ipc/BrowserChild.cpp

@@ -2285,8 +2285,9 @@ mozilla::ipc::IPCResult BrowserChild::RecvPrintPreview(
 
   sourceWindow->Print(printSettings,
                       /* aListener = */ nullptr, docShellToCloneInto,
-                      /* aIsPreview = */ true, std::move(aCallback),
-                      IgnoreErrors());
+                      nsGlobalWindowOuter::IsPreview::Yes,
+                      nsGlobalWindowOuter::BlockUntilDone::No,
+                      std::move(aCallback), IgnoreErrors());
 #endif
   return IPC_OK();
 }
@@ -2338,7 +2339,8 @@ mozilla::ipc::IPCResult BrowserChild::RecvPrint(const uint64_t& aOuterWindowID,
     outerWindow->Print(printSettings,
                        /* aListener = */ nullptr,
                        /* aWindowToCloneInto = */ nullptr,
-                       /* aIsPreview = */ false,
+                       nsGlobalWindowOuter::IsPreview::No,
+                       nsGlobalWindowOuter::BlockUntilDone::No,
                        /* aPrintPreviewCallback = */ nullptr, rv);
     if (NS_WARN_IF(rv.Failed())) {
       return IPC_OK();