Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3558 insertions, 0 deletions

diff --git a/layout/base/nsDocumentViewer.cpp b/layout/base/nsDocumentViewer.cpp
new file mode 100644
index 0000000000..ea03e8ea33
--- /dev/null
+++ b/layout/base/nsDocumentViewer.cpp
@@ -0,0 +1,3558 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* container for a document and its presentation */
+
+#include "gfxContext.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/RestyleManager.h"
+#include "mozilla/ServoStyleSet.h"
+#include "mozilla/StaticPrefs_print.h"
+#include "mozilla/Telemetry.h"
+#include "nsThreadUtils.h"
+#include "nscore.h"
+#include "nsCOMPtr.h"
+#include "nsCRT.h"
+#include "nsFrameSelection.h"
+#include "nsString.h"
+#include "nsReadableUtils.h"
+#include "nsIContent.h"
+#include "nsIContentViewer.h"
+#include "nsIDocumentViewerPrint.h"
+#include "nsIScreen.h"
+#include "mozilla/dom/AutoSuppressEventHandlingAndSuspend.h"
+#include "mozilla/dom/BrowsingContext.h"
+#include "mozilla/dom/BeforeUnloadEvent.h"
+#include "mozilla/dom/PopupBlocker.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/DocumentInlines.h"
+#include "mozilla/dom/DocGroup.h"
+#include "nsPresContext.h"
+#include "nsIFrame.h"
+#include "nsIWritablePropertyBag2.h"
+#include "nsSubDocumentFrame.h"
+#include "nsGenericHTMLElement.h"
+#include "nsStubMutationObserver.h"
+
+#include "nsISelectionListener.h"
+#include "mozilla/dom/Selection.h"
+#include "nsContentUtils.h"
+#ifdef ACCESSIBILITY
+#  include "mozilla/a11y/DocAccessible.h"
+#endif
+#include "mozilla/BasicEvents.h"
+#include "mozilla/Encoding.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/WeakPtr.h"
+#include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/StaticPrefs_javascript.h"
+#include "mozilla/StaticPrefs_fission.h"
+#include "mozilla/StaticPrefs_print.h"
+#include "mozilla/StyleSheet.h"
+#include "mozilla/StyleSheetInlines.h"
+
+#include "nsViewManager.h"
+#include "nsView.h"
+
+#include "nsPageSequenceFrame.h"
+#include "nsNetUtil.h"
+#include "nsIContentViewerEdit.h"
+#include "mozilla/css/Loader.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsDocShell.h"
+#include "nsIBaseWindow.h"
+#include "nsILayoutHistoryState.h"
+#include "nsIScreen.h"
+#include "nsCharsetSource.h"
+#include "mozilla/ReflowInput.h"
+#include "nsIImageLoadingContent.h"
+#include "nsCopySupport.h"
+#include "nsXULPopupManager.h"
+
+#include "nsIClipboardHelper.h"
+
+#include "nsPIDOMWindow.h"
+#include "nsGlobalWindow.h"
+#include "nsDOMNavigationTiming.h"
+#include "nsPIWindowRoot.h"
+#include "nsJSEnvironment.h"
+#include "nsFocusManager.h"
+
+#include "nsIScrollableFrame.h"
+#include "nsStyleSheetService.h"
+#include "nsILoadContext.h"
+#include "mozilla/ThrottledEventQueue.h"
+#include "nsIPromptCollection.h"
+#include "nsIPromptService.h"
+#include "imgIContainer.h"  // image animation mode constants
+#include "nsIXULRuntime.h"
+#include "nsSandboxFlags.h"
+
+#include "mozilla/DocLoadingTimelineMarker.h"
+
+//--------------------------
+// Printing Include
+//---------------------------
+#ifdef NS_PRINTING
+
+#  include "nsIWebBrowserPrint.h"
+
+#  include "nsPrintJob.h"
+#  include "nsDeviceContextSpecProxy.h"
+
+// Print Options
+#  include "nsIPrintSettings.h"
+#  include "nsIPrintSettingsService.h"
+#  include "nsISimpleEnumerator.h"
+
+#endif  // NS_PRINTING
+
+// focus
+#include "nsIDOMEventListener.h"
+#include "nsISelectionController.h"
+
+#include "mozilla/EventDispatcher.h"
+#include "nsISHEntry.h"
+#include "nsISHistory.h"
+#include "nsIWebNavigation.h"
+#include "mozilla/dom/XMLHttpRequestMainThread.h"
+
+// paint forcing
+#include <stdio.h>
+#include "mozilla/BasePrincipal.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/dom/ScriptLoader.h"
+#include "mozilla/dom/WindowGlobalChild.h"
+
+namespace mozilla {
+namespace dom {
+class PrintPreviewResultInfo;
+}  // namespace dom
+}  // namespace mozilla
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+using mozilla::layout::RemotePrintJobChild;
+using PrintPreviewResolver =
+    std::function<void(const mozilla::dom::PrintPreviewResultInfo&)>;
+
+//-----------------------------------------------------
+// LOGGING
+#include "LayoutLogging.h"
+#include "mozilla/Logging.h"
+
+extern mozilla::LazyLogModule gPageCacheLog;
+
+#ifdef NS_PRINTING
+mozilla::LazyLogModule gPrintingLog("printing");
+
+#  define PR_PL(_p1) MOZ_LOG(gPrintingLog, mozilla::LogLevel::Debug, _p1);
+#endif  // NS_PRINTING
+
+#define PRT_YESNO(_p) ((_p) ? "YES" : "NO")
+//-----------------------------------------------------
+
+class nsDocumentViewer;
+
+// a small delegate class used to avoid circular references
+
+class nsDocViewerSelectionListener final : public nsISelectionListener {
+ public:
+  // nsISupports interface...
+  NS_DECL_ISUPPORTS
+
+  // nsISelectionListerner interface
+  NS_DECL_NSISELECTIONLISTENER
+
+  explicit nsDocViewerSelectionListener(nsDocumentViewer* aDocViewer)
+      : mDocViewer(aDocViewer), mSelectionWasCollapsed(true) {}
+
+  void Disconnect() { mDocViewer = nullptr; }
+
+ protected:
+  virtual ~nsDocViewerSelectionListener() = default;
+
+  nsDocumentViewer* mDocViewer;
+  bool mSelectionWasCollapsed;
+};
+
+/** editor Implementation of the FocusListener interface */
+class nsDocViewerFocusListener final : public nsIDOMEventListener {
+ public:
+  explicit nsDocViewerFocusListener(nsDocumentViewer* aDocViewer)
+      : mDocViewer(aDocViewer) {}
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIDOMEVENTLISTENER
+
+  void Disconnect() { mDocViewer = nullptr; }
+
+ protected:
+  virtual ~nsDocViewerFocusListener() = default;
+
+  nsDocumentViewer* mDocViewer;
+};
+
+namespace viewer_detail {
+
+/**
+ * Mutation observer for use until we hand ourselves over to our SHEntry.
+ */
+class BFCachePreventionObserver final : public nsStubMutationObserver {
+ public:
+  explicit BFCachePreventionObserver(Document* aDocument)
+      : mDocument(aDocument) {}
+
+  NS_DECL_ISUPPORTS
+
+  NS_DECL_NSIMUTATIONOBSERVER_CHARACTERDATACHANGED
+  NS_DECL_NSIMUTATIONOBSERVER_ATTRIBUTECHANGED
+  NS_DECL_NSIMUTATIONOBSERVER_CONTENTAPPENDED
+  NS_DECL_NSIMUTATIONOBSERVER_CONTENTINSERTED
+  NS_DECL_NSIMUTATIONOBSERVER_CONTENTREMOVED
+  NS_DECL_NSIMUTATIONOBSERVER_NODEWILLBEDESTROYED
+
+  // Stop observing the document.
+  void Disconnect();
+
+ private:
+  ~BFCachePreventionObserver() = default;
+
+  // Helper for the work that needs to happen when mutations happen.
+  void MutationHappened();
+
+  Document* mDocument;  // Weak; we get notified if it dies
+};
+
+NS_IMPL_ISUPPORTS(BFCachePreventionObserver, nsIMutationObserver)
+
+void BFCachePreventionObserver::CharacterDataChanged(
+    nsIContent* aContent, const CharacterDataChangeInfo&) {
+  if (aContent->IsInNativeAnonymousSubtree()) {
+    return;
+  }
+  MutationHappened();
+}
+
+void BFCachePreventionObserver::AttributeChanged(Element* aElement,
+                                                 int32_t aNameSpaceID,
+                                                 nsAtom* aAttribute,
+                                                 int32_t aModType,
+                                                 const nsAttrValue* aOldValue) {
+  if (aElement->IsInNativeAnonymousSubtree()) {
+    return;
+  }
+  MutationHappened();
+}
+
+void BFCachePreventionObserver::ContentAppended(nsIContent* aFirstNewContent) {
+  if (aFirstNewContent->IsInNativeAnonymousSubtree()) {
+    return;
+  }
+  MutationHappened();
+}
+
+void BFCachePreventionObserver::ContentInserted(nsIContent* aChild) {
+  if (aChild->IsInNativeAnonymousSubtree()) {
+    return;
+  }
+  MutationHappened();
+}
+
+void BFCachePreventionObserver::ContentRemoved(nsIContent* aChild,
+                                               nsIContent* aPreviousSibling) {
+  if (aChild->IsInNativeAnonymousSubtree()) {
+    return;
+  }
+  MutationHappened();
+}
+
+void BFCachePreventionObserver::NodeWillBeDestroyed(nsINode* aNode) {
+  mDocument = nullptr;
+}
+
+void BFCachePreventionObserver::Disconnect() {
+  if (mDocument) {
+    mDocument->RemoveMutationObserver(this);
+    // It will no longer tell us when it goes away, so make sure we're
+    // not holding a dangling ref.
+    mDocument = nullptr;
+  }
+}
+
+void BFCachePreventionObserver::MutationHappened() {
+  MOZ_ASSERT(
+      mDocument,
+      "How can we not have a document but be getting notified for mutations?");
+  mDocument->DisallowBFCaching();
+  Disconnect();
+}
+
+}  // namespace viewer_detail
+
+using viewer_detail::BFCachePreventionObserver;
+
+//-------------------------------------------------------------
+class nsDocumentViewer final : public nsIContentViewer,
+                               public nsIContentViewerEdit,
+                               public nsIDocumentViewerPrint
+#ifdef NS_PRINTING
+    ,
+                               public nsIWebBrowserPrint
+#endif
+
+{
+  friend class nsDocViewerSelectionListener;
+  friend class nsPagePrintTimer;
+  friend class nsPrintJob;
+
+ public:
+  nsDocumentViewer();
+
+  // nsISupports interface...
+  NS_DECL_ISUPPORTS
+
+  // nsIContentViewer interface...
+  NS_DECL_NSICONTENTVIEWER
+
+  // nsIContentViewerEdit
+  NS_DECL_NSICONTENTVIEWEREDIT
+
+#ifdef NS_PRINTING
+  // nsIWebBrowserPrint
+  NS_DECL_NSIWEBBROWSERPRINT
+#endif
+
+  // nsIDocumentViewerPrint Printing Methods
+  NS_DECL_NSIDOCUMENTVIEWERPRINT
+
+ protected:
+  virtual ~nsDocumentViewer();
+
+ private:
+  /**
+   * Creates a view manager, root view, and widget for the root view, setting
+   * mViewManager and mWindow.
+   * @param aSize the initial size in appunits
+   * @param aContainerView the container view to hook our root view up
+   * to as a child, or null if this will be the root view manager
+   */
+  nsresult MakeWindow(const nsSize& aSize, nsView* aContainerView);
+
+  /**
+   * Create our device context
+   */
+  nsresult CreateDeviceContext(nsView* aContainerView);
+
+  /**
+   * If aDoCreation is true, this creates the device context, creates a
+   * prescontext if necessary, and calls MakeWindow.
+   *
+   * If aForceSetNewDocument is false, then SetNewDocument won't be
+   * called if the window's current document is already mDocument.
+   */
+  nsresult InitInternal(nsIWidget* aParentWidget, nsISupports* aState,
+                        mozilla::dom::WindowGlobalChild* aActor,
+                        const nsIntRect& aBounds, bool aDoCreation,
+                        bool aNeedMakeCX = true,
+                        bool aForceSetNewDocument = true);
+  /**
+   * @param aDoInitialReflow set to true if you want to kick off the initial
+   * reflow
+   */
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY
+  nsresult InitPresentationStuff(bool aDoInitialReflow);
+
+  already_AddRefed<nsINode> GetPopupNode();
+  already_AddRefed<nsINode> GetPopupLinkNode();
+  already_AddRefed<nsIImageLoadingContent> GetPopupImageNode();
+
+  void PrepareToStartLoad(void);
+
+  nsresult SyncParentSubDocMap();
+
+  void RemoveFocusListener();
+  void ReinitializeFocusListener();
+
+  mozilla::dom::Selection* GetDocumentSelection();
+
+  void DestroyPresShell();
+  void DestroyPresContext();
+
+  void InvalidatePotentialSubDocDisplayItem();
+
+  // Whether we should attach to the top level widget. This is true if we
+  // are sharing/recycling a single base widget and not creating multiple
+  // child widgets.
+  bool ShouldAttachToTopLevel();
+
+  std::tuple<const nsIFrame*, int32_t> GetCurrentSheetFrameAndNumber() const;
+
+ protected:
+  // Returns the current viewmanager.  Might be null.
+  nsViewManager* GetViewManager();
+
+  void DetachFromTopLevelWidget();
+
+  // IMPORTANT: The ownership implicit in the following member
+  // variables has been explicitly checked and set using nsCOMPtr
+  // for owning pointers and raw COM interface pointers for weak
+  // (ie, non owning) references. If you add any members to this
+  // class, please make the ownership explicit (pinkerton, scc).
+
+  WeakPtr<nsDocShell> mContainer;          // it owns me!
+  RefPtr<nsDeviceContext> mDeviceContext;  // We create and own this baby
+
+  // the following six items are explicitly in this order
+  // so they will be destroyed in the reverse order (pinkerton, scc)
+  nsCOMPtr<Document> mDocument;
+  nsCOMPtr<nsIWidget> mWindow;  // may be null
+  RefPtr<nsViewManager> mViewManager;
+  RefPtr<nsPresContext> mPresContext;
+  RefPtr<PresShell> mPresShell;
+
+  RefPtr<nsDocViewerSelectionListener> mSelectionListener;
+  RefPtr<nsDocViewerFocusListener> mFocusListener;
+
+  nsCOMPtr<nsIContentViewer> mPreviousViewer;
+  nsCOMPtr<nsISHEntry> mSHEntry;
+  // Observer that will prevent bfcaching if it gets notified.  This
+  // is non-null precisely when mSHEntry is non-null.
+  RefPtr<BFCachePreventionObserver> mBFCachePreventionObserver;
+
+  nsIWidget* mParentWidget;  // purposely won't be ref counted.  May be null
+  bool mAttachedToParent;    // view is attached to the parent widget
+
+  nsIntRect mBounds;
+
+  int16_t mNumURLStarts;
+  int16_t mDestroyBlockedCount;
+
+  unsigned mStopped : 1;
+  unsigned mLoaded : 1;
+  unsigned mDeferredWindowClose : 1;
+  // document management data
+  //   these items are specific to markup documents (html and xml)
+  //   may consider splitting these out into a subclass
+  unsigned mIsSticky : 1;
+  unsigned mInPermitUnload : 1;
+  unsigned mInPermitUnloadPrompt : 1;
+
+#ifdef NS_PRINTING
+  unsigned mClosingWhilePrinting : 1;
+
+#  if NS_PRINT_PREVIEW
+  RefPtr<nsPrintJob> mPrintJob;
+#  endif  // NS_PRINT_PREVIEW
+
+#endif  // NS_PRINTING
+
+  /* character set member data */
+  int32_t mReloadEncodingSource;
+  const Encoding* mReloadEncoding;
+
+  bool mIsPageMode;
+  bool mInitializedForPrintPreview;
+  bool mHidden;
+};
+
+class nsDocumentShownDispatcher : public Runnable {
+ public:
+  explicit nsDocumentShownDispatcher(nsCOMPtr<Document> aDocument)
+      : Runnable("nsDocumentShownDispatcher"), mDocument(aDocument) {}
+
+  NS_IMETHOD Run() override;
+
+ private:
+  nsCOMPtr<Document> mDocument;
+};
+
+//------------------------------------------------------------------
+// nsDocumentViewer
+//------------------------------------------------------------------
+
+//------------------------------------------------------------------
+already_AddRefed<nsIContentViewer> NS_NewContentViewer() {
+  RefPtr<nsDocumentViewer> viewer = new nsDocumentViewer();
+  return viewer.forget();
+}
+
+void nsDocumentViewer::PrepareToStartLoad() {
+  MOZ_DIAGNOSTIC_ASSERT(!GetIsPrintPreview(),
+                        "Print preview tab should never navigate");
+
+  mStopped = false;
+  mLoaded = false;
+  mAttachedToParent = false;
+  mDeferredWindowClose = false;
+
+#ifdef NS_PRINTING
+  mClosingWhilePrinting = false;
+
+  // Make sure we have destroyed it and cleared the data member
+  if (mPrintJob) {
+    mPrintJob->Destroy();
+    mPrintJob = nullptr;
+  }
+
+#endif  // NS_PRINTING
+}
+
+nsDocumentViewer::nsDocumentViewer()
+    : mParentWidget(nullptr),
+      mAttachedToParent(false),
+      mNumURLStarts(0),
+      mDestroyBlockedCount(0),
+      mStopped(false),
+      mLoaded(false),
+      mDeferredWindowClose(false),
+      mIsSticky(true),
+      mInPermitUnload(false),
+      mInPermitUnloadPrompt(false),
+#ifdef NS_PRINTING
+      mClosingWhilePrinting(false),
+#endif  // NS_PRINTING
+      mReloadEncodingSource(kCharsetUninitialized),
+      mReloadEncoding(nullptr),
+      mIsPageMode(false),
+      mInitializedForPrintPreview(false),
+      mHidden(false) {
+  PrepareToStartLoad();
+}
+
+NS_IMPL_ADDREF(nsDocumentViewer)
+NS_IMPL_RELEASE(nsDocumentViewer)
+
+NS_INTERFACE_MAP_BEGIN(nsDocumentViewer)
+  NS_INTERFACE_MAP_ENTRY(nsIContentViewer)
+  NS_INTERFACE_MAP_ENTRY(nsIContentViewerEdit)
+  NS_INTERFACE_MAP_ENTRY(nsIDocumentViewerPrint)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIContentViewer)
+#ifdef NS_PRINTING
+  NS_INTERFACE_MAP_ENTRY(nsIWebBrowserPrint)
+#endif
+NS_INTERFACE_MAP_END
+
+nsDocumentViewer::~nsDocumentViewer() {
+  if (mDocument) {
+    Close(nullptr);
+    mDocument->Destroy();
+  }
+
+#ifdef NS_PRINTING
+  if (mPrintJob) {
+    mPrintJob->Destroy();
+    mPrintJob = nullptr;
+  }
+#endif
+
+  MOZ_RELEASE_ASSERT(mDestroyBlockedCount == 0);
+  NS_ASSERTION(!mPresShell && !mPresContext,
+               "User did not call nsIContentViewer::Destroy");
+  if (mPresShell || mPresContext) {
+    // Make sure we don't hand out a reference to the content viewer to
+    // the SHEntry!
+    mSHEntry = nullptr;
+
+    Destroy();
+  }
+
+  if (mSelectionListener) {
+    mSelectionListener->Disconnect();
+  }
+
+  RemoveFocusListener();
+
+  // XXX(?) Revoke pending invalidate events
+}
+
+/*
+ * This method is called by the Document Loader once a document has
+ * been created for a particular data stream...  The content viewer
+ * must cache this document for later use when Init(...) is called.
+ *
+ * This method is also called when an out of band document.write() happens.
+ * In that case, the document passed in is the same as the previous document.
+ */
+/* virtual */
+void nsDocumentViewer::LoadStart(Document* aDocument) {
+  MOZ_ASSERT(aDocument);
+
+  if (!mDocument) {
+    mDocument = aDocument;
+  }
+}
+
+void nsDocumentViewer::RemoveFocusListener() {
+  if (RefPtr<nsDocViewerFocusListener> oldListener =
+          std::move(mFocusListener)) {
+    oldListener->Disconnect();
+    if (mDocument) {
+      mDocument->RemoveEventListener(u"focus"_ns, oldListener, false);
+      mDocument->RemoveEventListener(u"blur"_ns, oldListener, false);
+    }
+  }
+}
+
+void nsDocumentViewer::ReinitializeFocusListener() {
+  RemoveFocusListener();
+  mFocusListener = new nsDocViewerFocusListener(this);
+  if (mDocument) {
+    mDocument->AddEventListener(u"focus"_ns, mFocusListener, false, false);
+    mDocument->AddEventListener(u"blur"_ns, mFocusListener, false, false);
+  }
+}
+
+nsresult nsDocumentViewer::SyncParentSubDocMap() {
+  nsCOMPtr<nsIDocShell> docShell(mContainer);
+  if (!docShell) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> pwin(docShell->GetWindow());
+  if (!mDocument || !pwin) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<Element> element = pwin->GetFrameElementInternal();
+  if (!element) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIDocShellTreeItem> parent;
+  docShell->GetInProcessParent(getter_AddRefs(parent));
+
+  nsCOMPtr<nsPIDOMWindowOuter> parent_win =
+      parent ? parent->GetWindow() : nullptr;
+  if (!parent_win) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<Document> parent_doc = parent_win->GetDoc();
+  if (!parent_doc) {
+    return NS_OK;
+  }
+
+  if (mDocument && parent_doc->GetSubDocumentFor(element) != mDocument &&
+      parent_doc->EventHandlingSuppressed()) {
+    mDocument->SuppressEventHandling(parent_doc->EventHandlingSuppressed());
+  }
+  return parent_doc->SetSubDocumentFor(element, mDocument);
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::SetContainer(nsIDocShell* aContainer) {
+  mContainer = static_cast<nsDocShell*>(aContainer);
+
+  // We're loading a new document into the window where this document
+  // viewer lives, sync the parent document's frame element -> sub
+  // document map
+
+  return SyncParentSubDocMap();
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetContainer(nsIDocShell** aResult) {
+  NS_ENSURE_ARG_POINTER(aResult);
+
+  nsCOMPtr<nsIDocShell> container(mContainer);
+  container.swap(*aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::Init(nsIWidget* aParentWidget, const nsIntRect& aBounds,
+                       WindowGlobalChild* aActor) {
+  return InitInternal(aParentWidget, nullptr, aActor, aBounds, true);
+}
+
+nsresult nsDocumentViewer::InitPresentationStuff(bool aDoInitialReflow) {
+  // We assert this because initializing the pres shell could otherwise cause
+  // re-entrancy into nsDocumentViewer methods, which might cause a different
+  // pres shell to be created.  Callers of InitPresentationStuff should ensure
+  // the call is appropriately bounded by an nsAutoScriptBlocker to decide
+  // when it is safe for these re-entrant calls to be made.
+  MOZ_ASSERT(!nsContentUtils::IsSafeToRunScript(),
+             "InitPresentationStuff must only be called when scripts are "
+             "blocked");
+
+#ifdef NS_PRINTING
+  // When getting printed, either for print or print preview, the print job
+  // takes care of setting up the presentation of the document.
+  if (mPrintJob) {
+    return NS_OK;
+  }
+#endif
+
+  NS_ASSERTION(!mPresShell, "Someone should have destroyed the presshell!");
+
+  // Now make the shell for the document
+  mPresShell = mDocument->CreatePresShell(mPresContext, mViewManager);
+  if (!mPresShell) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (aDoInitialReflow) {
+    // Since Initialize() will create frames for *all* items
+    // that are currently in the document tree, we need to flush
+    // any pending notifications to prevent the content sink from
+    // duplicating layout frames for content it has added to the tree
+    // but hasn't notified the document about. (Bug 154018)
+    //
+    // Note that we are flushing before we add mPresShell as an observer
+    // to avoid bogus notifications.
+    mDocument->FlushPendingNotifications(FlushType::ContentAndNotify);
+  }
+
+  mPresShell->BeginObservingDocument();
+
+  // Initialize our view manager
+
+  {
+    int32_t p2a = mPresContext->AppUnitsPerDevPixel();
+    MOZ_ASSERT(
+        p2a ==
+        mPresContext->DeviceContext()->AppUnitsPerDevPixelAtUnitFullZoom());
+
+    nscoord width = p2a * mBounds.width;
+    nscoord height = p2a * mBounds.height;
+
+    mViewManager->SetWindowDimensions(width, height);
+    mPresContext->SetVisibleArea(nsRect(0, 0, width, height));
+    // We rely on the default zoom not being initialized until here.
+    mPresContext->RecomputeBrowsingContextDependentData();
+  }
+
+  if (mWindow && mDocument->IsTopLevelContentDocument()) {
+    // Set initial safe area insets
+    ScreenIntMargin windowSafeAreaInsets;
+    LayoutDeviceIntRect windowRect = mWindow->GetScreenBounds();
+    nsCOMPtr<nsIScreen> screen = mWindow->GetWidgetScreen();
+    if (screen) {
+      windowSafeAreaInsets = nsContentUtils::GetWindowSafeAreaInsets(
+          screen, mWindow->GetSafeAreaInsets(), windowRect);
+    }
+
+    mPresContext->SetSafeAreaInsets(windowSafeAreaInsets);
+  }
+
+  if (aDoInitialReflow) {
+    RefPtr<PresShell> presShell = mPresShell;
+    // Initial reflow
+    presShell->Initialize();
+  }
+
+  // now register ourselves as a selection listener, so that we get
+  // called when the selection changes in the window
+  if (!mSelectionListener) {
+    mSelectionListener = new nsDocViewerSelectionListener(this);
+  }
+
+  RefPtr<mozilla::dom::Selection> selection = GetDocumentSelection();
+  if (!selection) {
+    return NS_ERROR_FAILURE;
+  }
+
+  selection->AddSelectionListener(mSelectionListener);
+
+  ReinitializeFocusListener();
+
+  if (aDoInitialReflow && mDocument) {
+    nsCOMPtr<Document> document = mDocument;
+    document->ScrollToRef();
+  }
+
+  return NS_OK;
+}
+
+static nsPresContext* CreatePresContext(Document* aDocument,
+                                        nsPresContext::nsPresContextType aType,
+                                        nsView* aContainerView) {
+  if (aContainerView) {
+    return new nsPresContext(aDocument, aType);
+  }
+  return new nsRootPresContext(aDocument, aType);
+}
+
+//-----------------------------------------------
+// This method can be used to initial the "presentation"
+// The aDoCreation indicates whether it should create
+// all the new objects or just initialize the existing ones
+nsresult nsDocumentViewer::InitInternal(
+    nsIWidget* aParentWidget, nsISupports* aState, WindowGlobalChild* aActor,
+    const nsIntRect& aBounds, bool aDoCreation, bool aNeedMakeCX /*= true*/,
+    bool aForceSetNewDocument /* = true*/) {
+  // We don't want any scripts to run here. That can cause flushing,
+  // which can cause reentry into initialization of this document viewer,
+  // which would be disastrous.
+  nsAutoScriptBlocker blockScripts;
+
+  mParentWidget = aParentWidget;  // not ref counted
+  mBounds = aBounds;
+
+  nsresult rv = NS_OK;
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_NULL_POINTER);
+
+  nsView* containerView = FindContainerView();
+
+  bool makeCX = false;
+  if (aDoCreation) {
+    nsresult rv = CreateDeviceContext(containerView);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    // XXXbz this is a nasty hack to do with the fact that we create
+    // presentations both in Init() and in Show()...  Ideally we would only do
+    // it in one place (Show()) and require that callers call init(), open(),
+    // show() in that order or something.
+    if (!mPresContext &&
+        (aParentWidget || containerView || mDocument->IsBeingUsedAsImage() ||
+         (mDocument->GetDisplayDocument() &&
+          mDocument->GetDisplayDocument()->GetPresShell()))) {
+      // Create presentation context
+      if (mIsPageMode) {
+        // Presentation context already created in SetPageModeForTesting which
+        // is calling this method
+      } else {
+        mPresContext = CreatePresContext(
+            mDocument, nsPresContext::eContext_Galley, containerView);
+      }
+      NS_ENSURE_TRUE(mPresContext, NS_ERROR_OUT_OF_MEMORY);
+
+      nsresult rv = mPresContext->Init(mDeviceContext);
+      if (NS_FAILED(rv)) {
+        mPresContext = nullptr;
+        return rv;
+      }
+
+#if defined(NS_PRINTING) && defined(NS_PRINT_PREVIEW)
+      makeCX = !GetIsPrintPreview() &&
+               aNeedMakeCX;  // needs to be true except when we are already in
+                             // PP or we are enabling/disabling paginated mode.
+#else
+      makeCX = true;
+#endif
+    }
+
+    if (mPresContext) {
+      // Create the ViewManager and Root View...
+
+      // We must do this before we tell the script global object about
+      // this new document since doing that will cause us to re-enter
+      // into nsSubDocumentFrame code through reflows caused by
+      // FlushPendingNotifications() calls down the road...
+
+      rv = MakeWindow(nsSize(mPresContext->DevPixelsToAppUnits(aBounds.width),
+                             mPresContext->DevPixelsToAppUnits(aBounds.height)),
+                      containerView);
+      NS_ENSURE_SUCCESS(rv, rv);
+      Hide();
+
+#ifdef NS_PRINT_PREVIEW
+      if (mIsPageMode) {
+        // I'm leaving this in a broken state for the moment; we should
+        // be measuring/scaling with the print device context, not the
+        // screen device context, but this is good enough to allow
+        // printing reftests to work.
+        double pageWidth = 0, pageHeight = 0;
+        mPresContext->GetPrintSettings()->GetEffectivePageSize(&pageWidth,
+                                                               &pageHeight);
+        mPresContext->SetPageSize(
+            nsSize(mPresContext->CSSTwipsToAppUnits(NSToIntFloor(pageWidth)),
+                   mPresContext->CSSTwipsToAppUnits(NSToIntFloor(pageHeight))));
+        mPresContext->SetIsRootPaginatedDocument(true);
+        mPresContext->SetPageScale(1.0f);
+      }
+#endif
+    } else {
+      // Avoid leaking the old viewer.
+      if (mPreviousViewer) {
+        mPreviousViewer->Destroy();
+        mPreviousViewer = nullptr;
+      }
+    }
+  }
+
+  nsCOMPtr<nsIInterfaceRequestor> requestor(mContainer);
+  if (requestor) {
+    // Set script-context-owner in the document
+
+    nsCOMPtr<nsPIDOMWindowOuter> window = do_GetInterface(requestor);
+
+    if (window) {
+      nsCOMPtr<Document> curDoc = window->GetExtantDoc();
+      if (aForceSetNewDocument || curDoc != mDocument) {
+        rv = window->SetNewDocument(mDocument, aState, false, aActor);
+        if (NS_FAILED(rv)) {
+          Destroy();
+          return rv;
+        }
+      }
+    }
+  }
+
+  if (aDoCreation && mPresContext) {
+    // The ViewManager and Root View was created above (in
+    // MakeWindow())...
+
+    rv = InitPresentationStuff(!makeCX);
+  }
+
+  return rv;
+}
+
+void nsDocumentViewer::SetNavigationTiming(nsDOMNavigationTiming* timing) {
+  NS_ASSERTION(mDocument, "Must have a document to set navigation timing.");
+  if (mDocument) {
+    mDocument->SetNavigationTiming(timing);
+  }
+}
+
+//
+// LoadComplete(aStatus)
+//
+//   aStatus - The status returned from loading the document.
+//
+// This method is called by the container when the document has been
+// completely loaded.
+//
+NS_IMETHODIMP
+nsDocumentViewer::LoadComplete(nsresult aStatus) {
+  /* We need to protect ourself against auto-destruction in case the
+     window is closed while processing the OnLoad event.  See bug
+     http://bugzilla.mozilla.org/show_bug.cgi?id=78445 for more
+     explanation.
+  */
+  RefPtr<nsDocumentViewer> kungFuDeathGrip(this);
+
+  // Flush out layout so it's up-to-date by the time onload is called.
+  // Note that this could destroy the window, so do this before
+  // checking for our mDocument and its window.
+  if (mPresShell && !mStopped) {
+    // Hold strong ref because this could conceivably run script
+    RefPtr<PresShell> presShell = mPresShell;
+    presShell->FlushPendingNotifications(FlushType::Layout);
+  }
+
+  nsresult rv = NS_OK;
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_NOT_AVAILABLE);
+
+  // First, get the window from the document...
+  nsCOMPtr<nsPIDOMWindowOuter> window = mDocument->GetWindow();
+
+  mLoaded = true;
+
+  // Now, fire either an OnLoad or OnError event to the document...
+  bool restoring = false;
+  // XXXbz imagelib kills off the document load for a full-page image with
+  // NS_ERROR_PARSED_DATA_CACHED if it's in the cache.  So we want to treat
+  // that one as a success code; otherwise whether we fire onload for the image
+  // will depend on whether it's cached!
+  if (window &&
+      (NS_SUCCEEDED(aStatus) || aStatus == NS_ERROR_PARSED_DATA_CACHED)) {
+    // If this code changes, the code in nsDocLoader::DocLoaderIsEmpty
+    // that fires load events for document.open() cases might need to
+    // be updated too.
+    nsEventStatus status = nsEventStatus_eIgnore;
+    WidgetEvent event(true, eLoad);
+    event.mFlags.mBubbles = false;
+    event.mFlags.mCancelable = false;
+    // XXX Dispatching to |window|, but using |document| as the target.
+    event.mTarget = mDocument;
+
+    // If the document presentation is being restored, we don't want to fire
+    // onload to the document content since that would likely confuse scripts
+    // on the page.
+
+    RefPtr<nsDocShell> docShell = nsDocShell::Cast(window->GetDocShell());
+    NS_ENSURE_TRUE(docShell, NS_ERROR_UNEXPECTED);
+
+    // Unfortunately, docShell->GetRestoringDocument() might no longer be set
+    // correctly.  In particular, it can be false by now if someone took it upon
+    // themselves to block onload from inside restoration and unblock it later.
+    // But we can detect the restoring case very simply: by whether our
+    // document's readyState is COMPLETE.
+    restoring =
+        (mDocument->GetReadyStateEnum() == Document::READYSTATE_COMPLETE);
+    if (!restoring) {
+      NS_ASSERTION(
+          mDocument->GetReadyStateEnum() == Document::READYSTATE_INTERACTIVE ||
+              // test_stricttransportsecurity.html has old-style
+              // docshell-generated about:blank docs reach this code!
+              (mDocument->GetReadyStateEnum() ==
+                   Document::READYSTATE_UNINITIALIZED &&
+               NS_IsAboutBlank(mDocument->GetDocumentURI())),
+          "Bad readystate");
+#ifdef DEBUG
+      bool docShellThinksWeAreRestoring;
+      docShell->GetRestoringDocument(&docShellThinksWeAreRestoring);
+      MOZ_ASSERT(!docShellThinksWeAreRestoring,
+                 "How can docshell think we are restoring if we don't have a "
+                 "READYSTATE_COMPLETE document?");
+#endif  // DEBUG
+      nsCOMPtr<Document> d = mDocument;
+      mDocument->SetReadyStateInternal(Document::READYSTATE_COMPLETE);
+
+      RefPtr<nsDOMNavigationTiming> timing(d->GetNavigationTiming());
+      if (timing) {
+        timing->NotifyLoadEventStart();
+      }
+
+      // Dispatch observer notification to notify observers document load is
+      // complete.
+      nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
+      if (os) {
+        nsIPrincipal* principal = d->NodePrincipal();
+        os->NotifyObservers(ToSupports(d),
+                            principal->IsSystemPrincipal()
+                                ? "chrome-document-loaded"
+                                : "content-document-loaded",
+                            nullptr);
+      }
+
+      // Notify any devtools about the load.
+      if (TimelineConsumers::HasConsumer(docShell)) {
+        TimelineConsumers::AddMarkerForDocShell(
+            docShell, MakeUnique<DocLoadingTimelineMarker>("document::Load"));
+      }
+
+      nsPIDOMWindowInner* innerWindow = window->GetCurrentInnerWindow();
+      RefPtr<DocGroup> docGroup = d->GetDocGroup();
+      // It is possible that the parent document's load event fires earlier than
+      // childs' load event, and in this case we need to fire some artificial
+      // load events to make the parent thinks the load events for child has
+      // been done
+      if (innerWindow && DocGroup::TryToLoadIframesInBackground()) {
+        nsTArray<nsCOMPtr<nsIDocShell>> docShells;
+        nsCOMPtr<nsIDocShell> container(mContainer);
+        if (container) {
+          int32_t count;
+          container->GetInProcessChildCount(&count);
+          // We first find all background loading iframes that need to
+          // fire artificial load events, and instead of firing them as
+          // soon as we find them, we store them in an array, to prevent
+          // us from skipping some events.
+          for (int32_t i = 0; i < count; ++i) {
+            nsCOMPtr<nsIDocShellTreeItem> child;
+            container->GetInProcessChildAt(i, getter_AddRefs(child));
+            nsCOMPtr<nsIDocShell> childIDocShell = do_QueryInterface(child);
+            RefPtr<nsDocShell> docShell = nsDocShell::Cast(childIDocShell);
+            if (docShell && docShell->TreatAsBackgroundLoad() &&
+                docShell->GetDocument()->GetReadyStateEnum() <
+                    Document::READYSTATE_COMPLETE) {
+              docShells.AppendElement(childIDocShell);
+            }
+          }
+
+          // Re-iterate the stored docShells to fire artificial load events
+          for (size_t i = 0; i < docShells.Length(); ++i) {
+            RefPtr<nsDocShell> docShell = nsDocShell::Cast(docShells[i]);
+            if (docShell && docShell->TreatAsBackgroundLoad() &&
+                docShell->GetDocument()->GetReadyStateEnum() <
+                    Document::READYSTATE_COMPLETE) {
+              nsEventStatus status = nsEventStatus_eIgnore;
+              WidgetEvent event(true, eLoad);
+              event.mFlags.mBubbles = false;
+              event.mFlags.mCancelable = false;
+
+              nsCOMPtr<nsPIDOMWindowOuter> win = docShell->GetWindow();
+              nsCOMPtr<Element> element = win->GetFrameElementInternal();
+
+              docShell->SetFakeOnLoadDispatched();
+              EventDispatcher::Dispatch(element, nullptr, &event, nullptr,
+                                        &status);
+            }
+          }
+        }
+      }
+
+      d->SetLoadEventFiring(true);
+      RefPtr<nsPresContext> presContext = mPresContext;
+      EventDispatcher::Dispatch(window, presContext, &event, nullptr, &status);
+      d->SetLoadEventFiring(false);
+
+      if (docGroup && docShell->TreatAsBackgroundLoad()) {
+        docGroup->TryFlushIframePostMessages(docShell->GetOuterWindowID());
+      }
+
+      if (timing) {
+        timing->NotifyLoadEventEnd();
+      }
+
+      if (innerWindow) {
+        innerWindow->QueuePerformanceNavigationTiming();
+      }
+    }
+  } else {
+    // XXX: Should fire error event to the document...
+
+    // If our load was explicitly aborted, then we want to set our
+    // readyState to COMPLETE, and fire a readystatechange event.
+    if (aStatus == NS_BINDING_ABORTED && mDocument) {
+      mDocument->NotifyAbortedLoad();
+    }
+  }
+
+  // Notify the document that it has been shown (regardless of whether
+  // it was just loaded). Note: mDocument may be null now if the above
+  // firing of onload caused the document to unload. Or, mDocument may not be
+  // the "current active" document, if the above firing of onload caused our
+  // docshell to navigate away. NOTE: In this latter scenario, it's likely that
+  // we fired pagehide (when navigating away) without ever having fired
+  // pageshow, and that's pretty broken... Fortunately, this should be rare.
+  // (It requires us to spin the event loop in onload handler, e.g. via sync
+  // XHR, in order for the navigation-away to happen before onload completes.)
+  // We skip firing pageshow if we're currently handling unload, or if loading
+  // was explicitly aborted.
+  if (mDocument && mDocument->IsCurrentActiveDocument() &&
+      aStatus != NS_BINDING_ABORTED) {
+    // Re-get window, since it might have changed during above firing of onload
+    window = mDocument->GetWindow();
+    if (window) {
+      nsIDocShell* docShell = window->GetDocShell();
+      bool isInUnload;
+      if (docShell && NS_SUCCEEDED(docShell->GetIsInUnload(&isInUnload)) &&
+          !isInUnload) {
+        mDocument->OnPageShow(restoring, nullptr);
+      }
+    }
+  }
+
+  if (!mStopped) {
+    if (mDocument) {
+      nsCOMPtr<Document> document = mDocument;
+      document->ScrollToRef();
+    }
+
+    // Now that the document has loaded, we can tell the presshell
+    // to unsuppress painting.
+    if (mPresShell) {
+      RefPtr<PresShell> presShell = mPresShell;
+      presShell->UnsuppressPainting();
+      // mPresShell could have been removed now, see bug 378682/421432
+      if (mPresShell) {
+        mPresShell->LoadComplete();
+      }
+    }
+  }
+
+  if (mDocument && !restoring) {
+    mDocument->LoadEventFired();
+  }
+
+  // It's probably a good idea to GC soon since we have finished loading.
+  nsJSContext::PokeGC(
+      JS::GCReason::LOAD_END,
+      mDocument ? mDocument->GetWrapperPreserveColor() : nullptr);
+
+#ifdef NS_PRINTING
+  // Check to see if someone tried to print during the load
+  if (window) {
+    auto* outerWin = nsGlobalWindowOuter::Cast(window);
+    outerWin->StopDelayingPrintingUntilAfterLoad();
+    if (outerWin->DelayedPrintUntilAfterLoad()) {
+      // We call into the inner because it ensures there's an active document
+      // and such, and it also waits until the whole thing completes, which is
+      // nice because it allows us to close if needed right here.
+      if (RefPtr inner =
+              nsGlobalWindowInner::Cast(window->GetCurrentInnerWindow())) {
+        inner->Print(IgnoreErrors());
+      }
+      if (outerWin->DelayedCloseForPrinting()) {
+        outerWin->Close();
+      }
+    } else {
+      MOZ_ASSERT(!outerWin->DelayedCloseForPrinting());
+    }
+  }
+#endif
+
+  return rv;
+}
+
+bool nsDocumentViewer::GetLoadCompleted() { return mLoaded; }
+
+bool nsDocumentViewer::GetIsStopped() { return mStopped; }
+
+NS_IMETHODIMP
+nsDocumentViewer::PermitUnload(PermitUnloadAction aAction,
+                               bool* aPermitUnload) {
+  // We're going to be running JS and nested event loops, which could cause our
+  // DocShell to be destroyed. Make sure we stay alive until the end of the
+  // function.
+  RefPtr<nsDocumentViewer> kungFuDeathGrip(this);
+
+  if (StaticPrefs::dom_disable_beforeunload()) {
+    aAction = eDontPromptAndUnload;
+  }
+
+  *aPermitUnload = true;
+
+  RefPtr<BrowsingContext> bc = mContainer->GetBrowsingContext();
+  if (!bc) {
+    return NS_OK;
+  }
+
+  // Per spec, we need to increase the ignore-opens-during-unload counter while
+  // dispatching the "beforeunload" event on both the document we're currently
+  // dispatching the event to and the document that we explicitly asked to
+  // unload.
+  IgnoreOpensDuringUnload ignoreOpens(mDocument);
+
+  bool foundBlocker = false;
+  bool foundOOPListener = false;
+  bc->PreOrderWalk([&](BrowsingContext* aBC) {
+    if (!aBC->IsInProcess()) {
+      WindowContext* wc = aBC->GetCurrentWindowContext();
+      if (wc && wc->HasBeforeUnload()) {
+        foundOOPListener = true;
+      }
+    } else if (aBC->GetDocShell()) {
+      nsCOMPtr<nsIContentViewer> contentViewer(
+          aBC->GetDocShell()->GetContentViewer());
+      if (contentViewer &&
+          contentViewer->DispatchBeforeUnload() == eRequestBlockNavigation) {
+        foundBlocker = true;
+      }
+    }
+  });
+
+  if (!foundOOPListener) {
+    if (!foundBlocker) {
+      return NS_OK;
+    }
+    if (aAction != ePrompt) {
+      *aPermitUnload = aAction == eDontPromptAndUnload;
+      return NS_OK;
+    }
+  }
+
+  // NB: we nullcheck mDocument because it might now be dead as a result of
+  // the event being dispatched.
+  RefPtr<WindowGlobalChild> wgc(mDocument ? mDocument->GetWindowGlobalChild()
+                                          : nullptr);
+  if (!wgc) {
+    return NS_OK;
+  }
+
+  nsAutoSyncOperation sync(mDocument, SyncOperationBehavior::eSuspendInput);
+  AutoSuppressEventHandlingAndSuspend seh(bc->Group());
+
+  mInPermitUnloadPrompt = true;
+
+  bool done = false;
+  wgc->SendCheckPermitUnload(
+      foundBlocker, aAction,
+      [&](bool aPermit) {
+        done = true;
+        *aPermitUnload = aPermit;
+      },
+      [&](auto) {
+        // If the prompt aborted, we tell our consumer that it is not allowed
+        // to unload the page. One reason that prompts abort is that the user
+        // performed some action that caused the page to unload while our prompt
+        // was active. In those cases we don't want our consumer to also unload
+        // the page.
+        //
+        // XXX: Are there other cases where prompts can abort? Is it ok to
+        //      prevent unloading the page in those cases?
+        done = true;
+        *aPermitUnload = false;
+      });
+
+  SpinEventLoopUntil("nsDocumentViewer::PermitUnload"_ns,
+                     [&]() { return done; });
+
+  mInPermitUnloadPrompt = false;
+  return NS_OK;
+}
+
+MOZ_CAN_RUN_SCRIPT_BOUNDARY PermitUnloadResult
+nsDocumentViewer::DispatchBeforeUnload() {
+  AutoDontWarnAboutSyncXHR disableSyncXHRWarning;
+
+  if (!mDocument || mInPermitUnload || mInPermitUnloadPrompt) {
+    return eAllowNavigation;
+  }
+
+  // First, get the script global object from the document...
+  RefPtr<nsGlobalWindowOuter> window =
+      nsGlobalWindowOuter::Cast(mDocument->GetWindow());
+  if (!window) {
+    // This is odd, but not fatal
+    NS_WARNING("window not set for document!");
+    return eAllowNavigation;
+  }
+
+  NS_ASSERTION(nsContentUtils::IsSafeToRunScript(), "This is unsafe");
+
+  // https://html.spec.whatwg.org/multipage/browsing-the-web.html#prompt-to-unload-a-document
+  // Create an RAII object on mDocument that will increment the
+  // should-ignore-opens-during-unload counter on initialization
+  // and decrement it again when it goes out of score (regardless
+  // of how we exit this function).
+  IgnoreOpensDuringUnload ignoreOpens(mDocument);
+
+  // Now, fire an BeforeUnload event to the document and see if it's ok
+  // to unload...
+  nsPresContext* presContext = mDocument->GetPresContext();
+  RefPtr<BeforeUnloadEvent> event =
+      new BeforeUnloadEvent(mDocument, presContext, nullptr);
+  event->InitEvent(u"beforeunload"_ns, false, true);
+
+  // Dispatching to |window|, but using |document| as the target.
+  event->SetTarget(mDocument);
+  event->SetTrusted(true);
+
+  // In evil cases we might be destroyed while handling the
+  // onbeforeunload event, don't let that happen. (see also bug#331040)
+  RefPtr<nsDocumentViewer> kungFuDeathGrip(this);
+
+  {
+    // Never permit popups from the beforeunload handler, no matter
+    // how we get here.
+    AutoPopupStatePusher popupStatePusher(PopupBlocker::openAbused, true);
+
+    RefPtr<BrowsingContext> bc = mContainer->GetBrowsingContext();
+    NS_ASSERTION(bc, "should have a browsing context in document viewer");
+
+    // Never permit dialogs from the beforeunload handler
+    nsGlobalWindowOuter::TemporarilyDisableDialogs disableDialogs(bc);
+
+    Document::PageUnloadingEventTimeStamp timestamp(mDocument);
+
+    mInPermitUnload = true;
+    RefPtr<nsPresContext> presContext = mPresContext;
+    // TODO: Bug 1506441
+    EventDispatcher::DispatchDOMEvent(MOZ_KnownLive(ToSupports(window)),
+                                      nullptr, event, presContext, nullptr);
+    mInPermitUnload = false;
+  }
+
+  nsAutoString text;
+  event->GetReturnValue(text);
+
+  // NB: we nullcheck mDocument because it might now be dead as a result of
+  // the event being dispatched.
+  if (window->AreDialogsEnabled() && mDocument &&
+      !(mDocument->GetSandboxFlags() & SANDBOXED_MODALS) &&
+      (!StaticPrefs::dom_require_user_interaction_for_beforeunload() ||
+       mDocument->UserHasInteracted()) &&
+      (event->WidgetEventPtr()->DefaultPrevented() || !text.IsEmpty())) {
+    return eRequestBlockNavigation;
+  }
+  return eAllowNavigation;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetBeforeUnloadFiring(bool* aInEvent) {
+  *aInEvent = mInPermitUnload;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetInPermitUnload(bool* aInEvent) {
+  *aInEvent = mInPermitUnloadPrompt;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::PageHide(bool aIsUnload) {
+  AutoDontWarnAboutSyncXHR disableSyncXHRWarning;
+
+  mHidden = true;
+
+  if (!mDocument) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (aIsUnload) {
+    // Poke the GC. The window might be collectable garbage now.
+    nsJSContext::PokeGC(JS::GCReason::PAGE_HIDE,
+                        mDocument->GetWrapperPreserveColor(),
+                        TimeDuration::FromMilliseconds(
+                            StaticPrefs::javascript_options_gc_delay() * 2));
+  }
+
+  mDocument->OnPageHide(!aIsUnload, nullptr);
+
+  // inform the window so that the focus state is reset.
+  NS_ENSURE_STATE(mDocument);
+  nsPIDOMWindowOuter* window = mDocument->GetWindow();
+  if (window) window->PageHidden();
+
+  if (aIsUnload) {
+    // if Destroy() was called during OnPageHide(), mDocument is nullptr.
+    NS_ENSURE_STATE(mDocument);
+
+    // First, get the window from the document...
+    RefPtr<nsPIDOMWindowOuter> window = mDocument->GetWindow();
+
+    if (!window) {
+      // Fail if no window is available...
+      NS_WARNING("window not set for document!");
+      return NS_ERROR_NULL_POINTER;
+    }
+
+    // https://html.spec.whatwg.org/multipage/browsing-the-web.html#unload-a-document
+    // Create an RAII object on mDocument that will increment the
+    // should-ignore-opens-during-unload counter on initialization
+    // and decrement it again when it goes out of scope.
+    IgnoreOpensDuringUnload ignoreOpens(mDocument);
+
+    // Now, fire an Unload event to the document...
+    nsEventStatus status = nsEventStatus_eIgnore;
+    WidgetEvent event(true, eUnload);
+    event.mFlags.mBubbles = false;
+    // XXX Dispatching to |window|, but using |document| as the target.
+    event.mTarget = mDocument;
+
+    // Never permit popups from the unload handler, no matter how we get
+    // here.
+    AutoPopupStatePusher popupStatePusher(PopupBlocker::openAbused, true);
+
+    Document::PageUnloadingEventTimeStamp timestamp(mDocument);
+
+    RefPtr<nsPresContext> presContext = mPresContext;
+    EventDispatcher::Dispatch(window, presContext, &event, nullptr, &status);
+  }
+
+  // look for open menupopups and close them after the unload event, in case
+  // the unload event listeners open any new popups
+  nsContentUtils::HidePopupsInDocument(mDocument);
+
+  return NS_OK;
+}
+
+static void AttachContainerRecurse(nsIDocShell* aShell) {
+  nsCOMPtr<nsIContentViewer> viewer;
+  aShell->GetContentViewer(getter_AddRefs(viewer));
+  if (viewer) {
+    viewer->SetIsHidden(false);
+    Document* doc = viewer->GetDocument();
+    if (doc) {
+      doc->SetContainer(static_cast<nsDocShell*>(aShell));
+    }
+    if (PresShell* presShell = viewer->GetPresShell()) {
+      presShell->SetForwardingContainer(WeakPtr<nsDocShell>());
+    }
+  }
+
+  // Now recurse through the children
+  int32_t childCount;
+  aShell->GetInProcessChildCount(&childCount);
+  for (int32_t i = 0; i < childCount; ++i) {
+    nsCOMPtr<nsIDocShellTreeItem> childItem;
+    aShell->GetInProcessChildAt(i, getter_AddRefs(childItem));
+    nsCOMPtr<nsIDocShell> shell = do_QueryInterface(childItem);
+    AttachContainerRecurse(shell);
+  }
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::Open(nsISupports* aState, nsISHEntry* aSHEntry) {
+  NS_ENSURE_TRUE(mPresShell, NS_ERROR_NOT_INITIALIZED);
+
+  if (mDocument) {
+    mDocument->SetContainer(mContainer);
+  }
+
+  nsresult rv = InitInternal(mParentWidget, aState, nullptr, mBounds, false);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  mHidden = false;
+
+  if (mPresShell) mPresShell->SetForwardingContainer(WeakPtr<nsDocShell>());
+
+  // Rehook the child presentations.  The child shells are still in
+  // session history, so get them from there.
+
+  if (aSHEntry) {
+    nsCOMPtr<nsIDocShellTreeItem> item;
+    int32_t itemIndex = 0;
+    while (NS_SUCCEEDED(
+               aSHEntry->ChildShellAt(itemIndex++, getter_AddRefs(item))) &&
+           item) {
+      nsCOMPtr<nsIDocShell> shell = do_QueryInterface(item);
+      AttachContainerRecurse(shell);
+    }
+  }
+
+  SyncParentSubDocMap();
+
+  ReinitializeFocusListener();
+
+  // XXX re-enable image animations once that works correctly
+
+  PrepareToStartLoad();
+
+  // When loading a page from the bfcache with puppet widgets, we do the
+  // widget attachment here (it is otherwise done in MakeWindow, which is
+  // called for non-bfcache pages in the history, but not bfcache pages).
+  // Attachment is necessary, since we get detached when another page
+  // is browsed to. That is, if we are one page A, then when we go to
+  // page B, we detach. So page A's view has no widget. If we then go
+  // back to it, and it is in the bfcache, we will use that view, which
+  // doesn't have a widget. The attach call here will properly attach us.
+  if (nsIWidget::UsePuppetWidgets() && mPresContext &&
+      ShouldAttachToTopLevel()) {
+    // If the old view is already attached to our parent, detach
+    DetachFromTopLevelWidget();
+
+    nsViewManager* vm = GetViewManager();
+    MOZ_ASSERT(vm, "no view manager");
+    nsView* v = vm->GetRootView();
+    MOZ_ASSERT(v, "no root view");
+    MOZ_ASSERT(mParentWidget, "no mParentWidget to set");
+    v->AttachToTopLevelWidget(mParentWidget);
+
+    mAttachedToParent = true;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::Close(nsISHEntry* aSHEntry) {
+  // All callers are supposed to call close to break circular
+  // references.  If we do this stuff in the destructor, the
+  // destructor might never be called (especially if we're being
+  // used from JS.
+
+  mSHEntry = aSHEntry;
+
+  // Close is also needed to disable scripts during paint suppression,
+  // since we transfer the existing global object to the new document
+  // that is loaded.  In the future, the global object may become a proxy
+  // for an object that can be switched in and out so that we don't need
+  // to disable scripts during paint suppression.
+
+  if (!mDocument) return NS_OK;
+
+  if (mSHEntry) {
+    if (mBFCachePreventionObserver) {
+      mBFCachePreventionObserver->Disconnect();
+    }
+    mBFCachePreventionObserver = new BFCachePreventionObserver(mDocument);
+    mDocument->AddMutationObserver(mBFCachePreventionObserver);
+  }
+
+#ifdef NS_PRINTING
+  // A Close was called while we were printing
+  // so don't clear the ScriptGlobalObject
+  // or clear the mDocument below
+  if (mPrintJob && !mClosingWhilePrinting) {
+    mClosingWhilePrinting = true;
+  } else
+#endif
+  {
+    // out of band cleanup of docshell
+    mDocument->SetScriptGlobalObject(nullptr);
+
+    if (!mSHEntry && mDocument) mDocument->RemovedFromDocShell();
+  }
+
+  RemoveFocusListener();
+  return NS_OK;
+}
+
+static void DetachContainerRecurse(nsIDocShell* aShell) {
+  // Unhook this docshell's presentation
+  aShell->SynchronizeLayoutHistoryState();
+  nsCOMPtr<nsIContentViewer> viewer;
+  aShell->GetContentViewer(getter_AddRefs(viewer));
+  if (viewer) {
+    if (Document* doc = viewer->GetDocument()) {
+      doc->SetContainer(nullptr);
+    }
+    if (PresShell* presShell = viewer->GetPresShell()) {
+      auto weakShell = static_cast<nsDocShell*>(aShell);
+      presShell->SetForwardingContainer(weakShell);
+    }
+  }
+
+  // Now recurse through the children
+  int32_t childCount;
+  aShell->GetInProcessChildCount(&childCount);
+  for (int32_t i = 0; i < childCount; ++i) {
+    nsCOMPtr<nsIDocShellTreeItem> childItem;
+    aShell->GetInProcessChildAt(i, getter_AddRefs(childItem));
+    nsCOMPtr<nsIDocShell> shell = do_QueryInterface(childItem);
+    DetachContainerRecurse(shell);
+  }
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::Destroy() {
+  // Don't let the document get unloaded while we are printing.
+  // this could happen if we hit the back button during printing.
+  // We also keep the viewer from being cached in session history, since
+  // we require all documents there to be sanitized.
+  if (mDestroyBlockedCount != 0) {
+    return NS_OK;
+  }
+
+#ifdef NS_PRINTING
+  // Here is where we check to see if the document was still being prepared
+  // for printing when it was asked to be destroy from someone externally
+  // This usually happens if the document is unloaded while the user is in the
+  // Print Dialog
+  //
+  // So we flip the bool to remember that the document is going away
+  // and we can clean up and abort later after returning from the Print Dialog
+  if (mPrintJob && mPrintJob->CheckBeforeDestroy()) {
+    return NS_OK;
+  }
+#endif
+
+  // We want to make sure to disconnect mBFCachePreventionObserver before we
+  // Sanitize() below.
+  if (mBFCachePreventionObserver) {
+    mBFCachePreventionObserver->Disconnect();
+    mBFCachePreventionObserver = nullptr;
+  }
+
+  if (mSHEntry && mDocument && !mDocument->IsBFCachingAllowed()) {
+    // Just drop the SHEntry now and pretend like we never even tried to bfcache
+    // this viewer.  This should only happen when someone calls
+    // DisallowBFCaching() after CanSavePresentation() already ran.  Ensure that
+    // the SHEntry has no viewer and its state is synced up.  We want to do this
+    // via a stack reference, in case those calls mess with our members.
+    MOZ_LOG(gPageCacheLog, LogLevel::Debug,
+            ("BFCache not allowed, dropping SHEntry"));
+    nsCOMPtr<nsISHEntry> shEntry = std::move(mSHEntry);
+    shEntry->SetContentViewer(nullptr);
+    shEntry->SyncPresentationState();
+  }
+
+  // If we were told to put ourselves into session history instead of destroy
+  // the presentation, do that now.
+  if (mSHEntry) {
+    if (mPresShell) mPresShell->Freeze();
+
+    // Make sure the presentation isn't torn down by Hide().
+    mSHEntry->SetSticky(mIsSticky);
+    mIsSticky = true;
+
+    // Remove our root view from the view hierarchy.
+    if (mPresShell) {
+      nsViewManager* vm = mPresShell->GetViewManager();
+      if (vm) {
+        nsView* rootView = vm->GetRootView();
+
+        if (rootView) {
+          nsView* rootViewParent = rootView->GetParent();
+          if (rootViewParent) {
+            nsView* subdocview = rootViewParent->GetParent();
+            if (subdocview) {
+              nsIFrame* f = subdocview->GetFrame();
+              if (f) {
+                nsSubDocumentFrame* s = do_QueryFrame(f);
+                if (s) {
+                  s->ClearDisplayItems();
+                }
+              }
+            }
+            nsViewManager* parentVM = rootViewParent->GetViewManager();
+            if (parentVM) {
+              parentVM->RemoveChild(rootView);
+            }
+          }
+        }
+      }
+    }
+
+    Hide();
+
+    // This is after Hide() so that the user doesn't see the inputs clear.
+    if (mDocument) {
+      mDocument->Sanitize();
+    }
+
+    // Reverse ownership. Do this *after* calling sanitize so that sanitize
+    // doesn't cause mutations that make the SHEntry drop the presentation
+
+    // Grab a reference to mSHEntry before calling into things like
+    // SyncPresentationState that might mess with our members.
+    nsCOMPtr<nsISHEntry> shEntry =
+        std::move(mSHEntry);  // we'll need this below
+
+    MOZ_LOG(gPageCacheLog, LogLevel::Debug,
+            ("Storing content viewer into cache entry"));
+    shEntry->SetContentViewer(this);
+
+    // Always sync the presentation state.  That way even if someone screws up
+    // and shEntry has no window state at this point we'll be ok; we just won't
+    // cache ourselves.
+    shEntry->SyncPresentationState();
+    // XXX Synchronize layout history state to parent once bfcache is supported
+    //     in session-history-in-parent.
+
+    // Shut down accessibility for the document before we start to tear it down.
+#ifdef ACCESSIBILITY
+    if (mPresShell) {
+      a11y::DocAccessible* docAcc = mPresShell->GetDocAccessible();
+      if (docAcc) {
+        docAcc->Shutdown();
+      }
+    }
+#endif
+
+    // Break the link from the document/presentation to the docshell, so that
+    // link traversals cannot affect the currently-loaded document.
+    // When the presentation is restored, Open() and InitInternal() will reset
+    // these pointers to their original values.
+
+    if (mDocument) {
+      mDocument->SetContainer(nullptr);
+    }
+    if (mPresShell) {
+      mPresShell->SetForwardingContainer(mContainer);
+    }
+
+    // Do the same for our children.  Note that we need to get the child
+    // docshells from the SHEntry now; the docshell will have cleared them.
+    nsCOMPtr<nsIDocShellTreeItem> item;
+    int32_t itemIndex = 0;
+    while (NS_SUCCEEDED(
+               shEntry->ChildShellAt(itemIndex++, getter_AddRefs(item))) &&
+           item) {
+      nsCOMPtr<nsIDocShell> shell = do_QueryInterface(item);
+      DetachContainerRecurse(shell);
+    }
+
+    return NS_OK;
+  }
+
+  // The document was not put in the bfcache
+
+  // Protect against pres shell destruction running scripts and re-entrantly
+  // creating a new presentation.
+  nsAutoScriptBlocker scriptBlocker;
+
+  if (mPresShell) {
+    DestroyPresShell();
+  }
+  if (mDocument) {
+    mDocument->Destroy();
+    mDocument = nullptr;
+  }
+
+  // All callers are supposed to call destroy to break circular
+  // references.  If we do this stuff in the destructor, the
+  // destructor might never be called (especially if we're being
+  // used from JS.
+
+#ifdef NS_PRINTING
+  if (mPrintJob) {
+    RefPtr<nsPrintJob> printJob = std::move(mPrintJob);
+#  ifdef NS_PRINT_PREVIEW
+    if (printJob->CreatedForPrintPreview()) {
+      printJob->FinishPrintPreview();
+    }
+#  endif
+    printJob->Destroy();
+    MOZ_ASSERT(!mPrintJob,
+               "mPrintJob shouldn't be recreated while destroying it");
+  }
+#endif
+
+  // Avoid leaking the old viewer.
+  if (mPreviousViewer) {
+    mPreviousViewer->Destroy();
+    mPreviousViewer = nullptr;
+  }
+
+  mDeviceContext = nullptr;
+
+  if (mPresContext) {
+    DestroyPresContext();
+  }
+
+  mWindow = nullptr;
+  mViewManager = nullptr;
+  mContainer = WeakPtr<nsDocShell>();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::Stop(void) {
+  NS_ASSERTION(mDocument, "Stop called too early or too late");
+  if (mDocument) {
+    mDocument->StopDocumentLoad();
+  }
+
+  mStopped = true;
+
+  if (!mLoaded && mPresShell) {
+    // Well, we might as well paint what we have so far.
+    RefPtr<PresShell> presShell = mPresShell;  // bug 378682
+    presShell->UnsuppressPainting();
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetDOMDocument(Document** aResult) {
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_NOT_AVAILABLE);
+  nsCOMPtr<Document> document = mDocument;
+  document.forget(aResult);
+  return NS_OK;
+}
+
+Document* nsDocumentViewer::GetDocument() { return mDocument; }
+
+nsresult nsDocumentViewer::SetDocument(Document* aDocument) {
+  // Assumptions:
+  //
+  // 1) this document viewer has been initialized with a call to Init().
+  // 2) the stylesheets associated with the document have been added
+  // to the document.
+
+  // XXX Right now, this method assumes that the layout of the current
+  // document hasn't started yet.  More cleanup will probably be
+  // necessary to make this method work for the case when layout *has*
+  // occurred for the current document.
+  // That work can happen when and if it is needed.
+
+  if (!aDocument) return NS_ERROR_NULL_POINTER;
+
+  return SetDocumentInternal(aDocument, false);
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::SetDocumentInternal(Document* aDocument,
+                                      bool aForceReuseInnerWindow) {
+  MOZ_ASSERT(aDocument);
+
+  // Set new container
+  aDocument->SetContainer(mContainer);
+
+  if (mDocument != aDocument) {
+    if (aForceReuseInnerWindow) {
+      // Transfer the navigation timing information to the new document, since
+      // we're keeping the same inner and hence should really have the same
+      // timing information.
+      aDocument->SetNavigationTiming(mDocument->GetNavigationTiming());
+    }
+
+    if (mDocument &&
+        (mDocument->IsStaticDocument() || aDocument->IsStaticDocument())) {
+      nsContentUtils::AddScriptRunner(NewRunnableMethod(
+          "Document::Destroy", mDocument, &Document::Destroy));
+    }
+
+    // Clear the list of old child docshells. Child docshells for the new
+    // document will be constructed as frames are created.
+    if (!aDocument->IsStaticDocument()) {
+      nsCOMPtr<nsIDocShell> node(mContainer);
+      if (node) {
+        int32_t count;
+        node->GetInProcessChildCount(&count);
+        for (int32_t i = 0; i < count; ++i) {
+          nsCOMPtr<nsIDocShellTreeItem> child;
+          node->GetInProcessChildAt(0, getter_AddRefs(child));
+          node->RemoveChild(child);
+        }
+      }
+    }
+
+    // Replace the old document with the new one. Do this only when
+    // the new document really is a new document.
+    mDocument = aDocument;
+
+    // Set the script global object on the new document
+    nsCOMPtr<nsPIDOMWindowOuter> window =
+        mContainer ? mContainer->GetWindow() : nullptr;
+    if (window) {
+      nsresult rv =
+          window->SetNewDocument(aDocument, nullptr, aForceReuseInnerWindow);
+      if (NS_FAILED(rv)) {
+        Destroy();
+        return rv;
+      }
+    }
+  }
+
+  nsresult rv = SyncParentSubDocMap();
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Replace the current pres shell with a new shell for the new document
+
+  // Protect against pres shell destruction running scripts and re-entrantly
+  // creating a new presentation.
+  nsAutoScriptBlocker scriptBlocker;
+
+  if (mPresShell) {
+    DestroyPresShell();
+  }
+
+  if (mPresContext) {
+    DestroyPresContext();
+
+    mWindow = nullptr;
+    rv = InitInternal(mParentWidget, nullptr, nullptr, mBounds, true, true,
+                      false);
+  }
+
+  return rv;
+}
+
+PresShell* nsDocumentViewer::GetPresShell() { return mPresShell; }
+
+nsPresContext* nsDocumentViewer::GetPresContext() { return mPresContext; }
+
+nsViewManager* nsDocumentViewer::GetViewManager() { return mViewManager; }
+
+NS_IMETHODIMP
+nsDocumentViewer::GetBounds(nsIntRect& aResult) {
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_NOT_AVAILABLE);
+  aResult = mBounds;
+  return NS_OK;
+}
+
+nsIContentViewer* nsDocumentViewer::GetPreviousViewer() {
+  return mPreviousViewer;
+}
+
+void nsDocumentViewer::SetPreviousViewer(nsIContentViewer* aViewer) {
+  // NOTE:  |Show| sets |mPreviousViewer| to null without calling this
+  // function.
+
+  if (aViewer) {
+    NS_ASSERTION(!mPreviousViewer,
+                 "can't set previous viewer when there already is one");
+
+    // In a multiple chaining situation (which occurs when running a thrashing
+    // test like i-bench or jrgm's tests with no delay), we can build up a
+    // whole chain of viewers.  In order to avoid this, we always set our
+    // previous viewer to the MOST previous viewer in the chain, and then dump
+    // the intermediate link from the chain.  This ensures that at most only 2
+    // documents are alive and undestroyed at any given time (the one that is
+    // showing and the one that is loading with painting suppressed). It's very
+    // important that if this ever gets changed the code before the
+    // RestorePresentation call in nsDocShell::InternalLoad be changed
+    // accordingly.
+    //
+    // Make sure we hold a strong ref to prevViewer here, since we'll
+    // tell aViewer to drop it.
+    nsCOMPtr<nsIContentViewer> prevViewer = aViewer->GetPreviousViewer();
+    if (prevViewer) {
+      aViewer->SetPreviousViewer(nullptr);
+      aViewer->Destroy();
+      return SetPreviousViewer(prevViewer);
+    }
+  }
+
+  mPreviousViewer = aViewer;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::SetBoundsWithFlags(const nsIntRect& aBounds,
+                                     uint32_t aFlags) {
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_NOT_AVAILABLE);
+
+  bool boundsChanged = !mBounds.IsEqualEdges(aBounds);
+  mBounds = aBounds;
+
+  if (mWindow && !mAttachedToParent) {
+    // Resize the widget, but don't trigger repaint. Layout will generate
+    // repaint requests during reflow.
+    mWindow->Resize(aBounds.x, aBounds.y, aBounds.width, aBounds.height, false);
+  } else if (mPresContext && mViewManager) {
+    // Ensure presContext's deviceContext is up to date, as we sometimes get
+    // here before a resolution-change notification has been fully handled
+    // during display configuration changes, especially when there are lots
+    // of windows/widgets competing to handle the notifications.
+    // (See bug 1154125.)
+    if (mPresContext->DeviceContext()->CheckDPIChange()) {
+      mPresContext->UIResolutionChangedSync();
+    }
+
+    int32_t p2a = mPresContext->AppUnitsPerDevPixel();
+    nscoord width = NSIntPixelsToAppUnits(mBounds.width, p2a);
+    nscoord height = NSIntPixelsToAppUnits(mBounds.height, p2a);
+    nsView* rootView = mViewManager->GetRootView();
+    if (boundsChanged && rootView) {
+      nsRect viewDims = rootView->GetDimensions();
+      // If the view/frame tree and prescontext visible area already has the new
+      // size but we did not, then it's likely that we got reflowed in response
+      // to a call to GetContentSize. Thus there is a disconnect between the
+      // size on the document viewer/docshell/containing widget and view
+      // tree/frame tree/prescontext visible area). SetWindowDimensions compares
+      // to the root view dimenstions to determine if it needs to do anything;
+      // if they are the same as the new size it won't do anything, but we still
+      // need to invalidate because what we want to draw to the screen has
+      // changed.
+      if (viewDims.width == width && viewDims.height == height) {
+        nsIFrame* f = rootView->GetFrame();
+        if (f) {
+          f->InvalidateFrame();
+        }
+      }
+    }
+
+    mViewManager->SetWindowDimensions(
+        width, height, !!(aFlags & nsIContentViewer::eDelayResize));
+  }
+
+  // If there's a previous viewer, it's the one that's actually showing,
+  // so be sure to resize it as well so it paints over the right area.
+  // This may slow down the performance of the new page load, but resize
+  // during load is also probably a relatively unusual condition
+  // relating to things being hidden while something is loaded.  It so
+  // happens that Firefox does this a good bit with its infobar, and it
+  // looks ugly if we don't do this.
+  if (mPreviousViewer) {
+    nsCOMPtr<nsIContentViewer> previousViewer = mPreviousViewer;
+    previousViewer->SetBounds(aBounds);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::SetBounds(const nsIntRect& aBounds) {
+  return SetBoundsWithFlags(aBounds, 0);
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::Move(int32_t aX, int32_t aY) {
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_NOT_AVAILABLE);
+  mBounds.MoveTo(aX, aY);
+  if (mWindow) {
+    mWindow->Move(aX, aY);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::Show() {
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_NOT_AVAILABLE);
+
+  // We don't need the previous viewer anymore since we're not
+  // displaying it.
+  if (mPreviousViewer) {
+    // This little dance *may* only be to keep
+    // PresShell::EndObservingDocument happy, but I'm not sure.
+    nsCOMPtr<nsIContentViewer> prevViewer(mPreviousViewer);
+    mPreviousViewer = nullptr;
+    prevViewer->Destroy();
+
+    // Make sure we don't have too many cached ContentViewers
+    nsCOMPtr<nsIDocShellTreeItem> treeItem(mContainer);
+    if (treeItem) {
+      // We need to find the root DocShell since only that object has an
+      // SHistory and we need the SHistory to evict content viewers
+      nsCOMPtr<nsIDocShellTreeItem> root;
+      treeItem->GetInProcessSameTypeRootTreeItem(getter_AddRefs(root));
+      nsCOMPtr<nsIWebNavigation> webNav = do_QueryInterface(root);
+      RefPtr<ChildSHistory> history = webNav->GetSessionHistory();
+      if (!mozilla::SessionHistoryInParent() && history) {
+        int32_t prevIndex, loadedIndex;
+        nsCOMPtr<nsIDocShell> docShell = do_QueryInterface(treeItem);
+        docShell->GetPreviousEntryIndex(&prevIndex);
+        docShell->GetLoadedEntryIndex(&loadedIndex);
+        MOZ_LOG(gPageCacheLog, LogLevel::Verbose,
+                ("About to evict content viewers: prev=%d, loaded=%d",
+                 prevIndex, loadedIndex));
+        history->LegacySHistory()->EvictOutOfRangeContentViewers(loadedIndex);
+      }
+    }
+  }
+
+  if (mWindow) {
+    // When attached to a top level xul window, we do not need to call
+    // Show on the widget. Underlying window management code handles
+    // this when the window is initialized.
+    if (!mAttachedToParent) {
+      mWindow->Show(true);
+    }
+  }
+
+  // Hold on to the document so we can use it after the script blocker below
+  // has been released (which might re-entrantly call into other
+  // nsDocumentViewer methods).
+  nsCOMPtr<Document> document = mDocument;
+
+  if (mDocument && !mPresShell) {
+    // The InitPresentationStuff call below requires a script blocker, because
+    // its PresShell::Initialize call can cause scripts to run and therefore
+    // re-entrant calls to nsDocumentViewer methods to be made.
+    nsAutoScriptBlocker scriptBlocker;
+
+    NS_ASSERTION(!mWindow, "Window already created but no presshell?");
+
+    nsCOMPtr<nsIBaseWindow> base_win(mContainer);
+    if (base_win) {
+      base_win->GetParentWidget(&mParentWidget);
+      if (mParentWidget) {
+        // GetParentWidget AddRefs, but mParentWidget is weak
+        mParentWidget->Release();
+      }
+    }
+
+    nsView* containerView = FindContainerView();
+
+    nsresult rv = CreateDeviceContext(containerView);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    // Create presentation context
+    NS_ASSERTION(!mPresContext,
+                 "Shouldn't have a prescontext if we have no shell!");
+    mPresContext = CreatePresContext(mDocument, nsPresContext::eContext_Galley,
+                                     containerView);
+    NS_ENSURE_TRUE(mPresContext, NS_ERROR_OUT_OF_MEMORY);
+
+    rv = mPresContext->Init(mDeviceContext);
+    if (NS_FAILED(rv)) {
+      mPresContext = nullptr;
+      return rv;
+    }
+
+    rv = MakeWindow(nsSize(mPresContext->DevPixelsToAppUnits(mBounds.width),
+                           mPresContext->DevPixelsToAppUnits(mBounds.height)),
+                    containerView);
+    if (NS_FAILED(rv)) return rv;
+
+    if (mPresContext) {
+      Hide();
+
+      rv = InitPresentationStuff(mDocument->MayStartLayout());
+    }
+
+    // If we get here the document load has already started and the
+    // window is shown because some JS on the page caused it to be
+    // shown...
+
+    if (mPresShell) {
+      RefPtr<PresShell> presShell = mPresShell;  // bug 378682
+      presShell->UnsuppressPainting();
+    }
+  }
+
+  // Notify observers that a new page has been shown. This will get run
+  // from the event loop after we actually draw the page.
+  RefPtr<nsDocumentShownDispatcher> event =
+      new nsDocumentShownDispatcher(document);
+  document->Dispatch(TaskCategory::Other, event.forget());
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::Hide() {
+  if (!mAttachedToParent && mWindow) {
+    mWindow->Show(false);
+  }
+
+  if (!mPresShell) return NS_OK;
+
+  NS_ASSERTION(mPresContext, "Can't have a presshell and no prescontext!");
+
+  // Avoid leaking the old viewer.
+  if (mPreviousViewer) {
+    mPreviousViewer->Destroy();
+    mPreviousViewer = nullptr;
+  }
+
+  if (mIsSticky) {
+    // This window is sticky, that means that it might be shown again
+    // and we don't want the presshell n' all that to be thrown away
+    // just because the window is hidden.
+
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIDocShell> docShell(mContainer);
+  if (docShell) {
+#ifdef DEBUG
+    nsCOMPtr<nsIContentViewer> currentViewer;
+    docShell->GetContentViewer(getter_AddRefs(currentViewer));
+    MOZ_ASSERT(currentViewer == this);
+#endif
+    nsCOMPtr<nsILayoutHistoryState> layoutState;
+    mPresShell->CaptureHistoryState(getter_AddRefs(layoutState));
+  }
+
+  // Do not run ScriptRunners queued by DestroyPresShell() in the intermediate
+  // state before we're done destroying PresShell, PresContext, ViewManager,
+  // etc.
+  nsAutoScriptBlocker scriptBlocker;
+
+  DestroyPresShell();
+
+  DestroyPresContext();
+
+  mViewManager = nullptr;
+  mWindow = nullptr;
+  mDeviceContext = nullptr;
+  mParentWidget = nullptr;
+
+  nsCOMPtr<nsIBaseWindow> base_win(mContainer);
+
+  if (base_win && !mAttachedToParent) {
+    base_win->SetParentWidget(nullptr);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetSticky(bool* aSticky) {
+  *aSticky = mIsSticky;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::SetSticky(bool aSticky) {
+  mIsSticky = aSticky;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::ClearHistoryEntry() {
+  if (mDocument) {
+    nsJSContext::PokeGC(JS::GCReason::PAGE_HIDE,
+                        mDocument->GetWrapperPreserveColor(),
+                        TimeDuration::FromMilliseconds(
+                            StaticPrefs::javascript_options_gc_delay() * 2));
+  }
+
+  mSHEntry = nullptr;
+  return NS_OK;
+}
+
+//-------------------------------------------------------
+
+nsresult nsDocumentViewer::MakeWindow(const nsSize& aSize,
+                                      nsView* aContainerView) {
+  if (GetIsPrintPreview()) {
+    return NS_OK;
+  }
+
+  bool shouldAttach = ShouldAttachToTopLevel();
+
+  if (shouldAttach) {
+    // If the old view is already attached to our parent, detach
+    DetachFromTopLevelWidget();
+  }
+
+  mViewManager = new nsViewManager();
+
+  nsDeviceContext* dx = mPresContext->DeviceContext();
+
+  nsresult rv = mViewManager->Init(dx);
+  if (NS_FAILED(rv)) return rv;
+
+  // The root view is always at 0,0.
+  nsRect tbounds(nsPoint(0, 0), aSize);
+  // Create a view
+  nsView* view = mViewManager->CreateView(tbounds, aContainerView);
+  if (!view) return NS_ERROR_OUT_OF_MEMORY;
+
+  // Create a widget if we were given a parent widget or don't have a
+  // container view that we can hook up to without a widget.
+  // Don't create widgets for ResourceDocs (external resources & svg images),
+  // because when they're displayed, they're painted into *another* document's
+  // widget.
+  if (!mDocument->IsResourceDoc() && (mParentWidget || !aContainerView)) {
+    // pass in a native widget to be the parent widget ONLY if the view
+    // hierarchy will stand alone. otherwise the view will find its own parent
+    // widget and "do the right thing" to establish a parent/child widget
+    // relationship
+    nsWidgetInitData initData;
+    nsWidgetInitData* initDataPtr;
+    if (!mParentWidget) {
+      initDataPtr = &initData;
+      initData.mWindowType = eWindowType_invisible;
+    } else {
+      initDataPtr = nullptr;
+    }
+
+    if (shouldAttach) {
+      // Reuse the top level parent widget.
+      rv = view->AttachToTopLevelWidget(mParentWidget);
+      mAttachedToParent = true;
+    } else if (!aContainerView && mParentWidget) {
+      rv = view->CreateWidgetForParent(mParentWidget, initDataPtr, true, false);
+    } else {
+      rv = view->CreateWidget(initDataPtr, true, false);
+    }
+    if (NS_FAILED(rv)) return rv;
+  }
+
+  // Setup hierarchical relationship in view manager
+  mViewManager->SetRootView(view);
+
+  mWindow = view->GetWidget();
+
+  // This SetFocus is necessary so the Arrow Key and Page Key events
+  // go to the scrolled view as soon as the Window is created instead of going
+  // to the browser window (this enables keyboard scrolling of the document)
+  // mWindow->SetFocus();
+
+  return rv;
+}
+
+void nsDocumentViewer::DetachFromTopLevelWidget() {
+  if (mViewManager) {
+    nsView* oldView = mViewManager->GetRootView();
+    if (oldView && oldView->IsAttachedToTopLevel()) {
+      oldView->DetachFromTopLevelWidget();
+    }
+  }
+  mAttachedToParent = false;
+}
+
+nsView* nsDocumentViewer::FindContainerView() {
+  if (!mContainer) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIDocShell> docShell(mContainer);
+  nsCOMPtr<nsPIDOMWindowOuter> pwin(docShell->GetWindow());
+  if (!pwin) {
+    return nullptr;
+  }
+
+  nsCOMPtr<Element> containerElement = pwin->GetFrameElementInternal();
+  if (!containerElement) {
+    return nullptr;
+  }
+
+  nsIFrame* subdocFrame = containerElement->GetPrimaryFrame();
+  if (!subdocFrame) {
+    // XXX Silenced by default in bug 1175289
+    LAYOUT_WARNING("Subdocument container has no frame");
+    return nullptr;
+  }
+
+  // Check subdocFrame just to be safe. If this somehow fails we treat that as
+  // display:none, the document is not displayed.
+  if (!subdocFrame->IsSubDocumentFrame()) {
+    NS_WARNING_ASSERTION(subdocFrame->Type() == LayoutFrameType::None,
+                         "Subdocument container has non-subdocument frame");
+    return nullptr;
+  }
+
+  NS_ASSERTION(subdocFrame->GetView(), "Subdoc frames must have views");
+  return static_cast<nsSubDocumentFrame*>(subdocFrame)->EnsureInnerView();
+}
+
+nsresult nsDocumentViewer::CreateDeviceContext(nsView* aContainerView) {
+  MOZ_ASSERT(!mPresShell && !mWindow,
+             "This will screw up our existing presentation");
+  MOZ_ASSERT(mDocument, "Gotta have a document here");
+
+  Document* doc = mDocument->GetDisplayDocument();
+  if (doc) {
+    NS_ASSERTION(!aContainerView,
+                 "External resource document embedded somewhere?");
+    // We want to use our display document's device context if possible
+    nsPresContext* ctx = doc->GetPresContext();
+    if (ctx) {
+      mDeviceContext = ctx->DeviceContext();
+      return NS_OK;
+    }
+  }
+
+  // Create a device context even if we already have one, since our widget
+  // might have changed.
+  nsIWidget* widget = nullptr;
+  if (aContainerView) {
+    widget = aContainerView->GetNearestWidget(nullptr);
+  }
+  if (!widget) {
+    widget = mParentWidget;
+  }
+  if (widget) {
+    widget = widget->GetTopLevelWidget();
+  }
+
+  mDeviceContext = new nsDeviceContext();
+  mDeviceContext->Init(widget);
+  return NS_OK;
+}
+
+// Return the selection for the document. Note that text fields have their
+// own selection, which cannot be accessed with this method.
+mozilla::dom::Selection* nsDocumentViewer::GetDocumentSelection() {
+  if (!mPresShell) {
+    return nullptr;
+  }
+
+  return mPresShell->GetCurrentSelection(SelectionType::eNormal);
+}
+
+/* ============================================================================
+ * nsIContentViewerEdit
+ * ============================================================================
+ */
+
+MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP nsDocumentViewer::ClearSelection() {
+  // use nsCopySupport::GetSelectionForCopy() ?
+  RefPtr<mozilla::dom::Selection> selection = GetDocumentSelection();
+  if (!selection) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult rv;
+  selection->CollapseToStart(rv);
+  return rv.StealNSResult();
+}
+
+MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP nsDocumentViewer::SelectAll() {
+  // XXX this is a temporary implementation copied from nsWebShell
+  // for now. I think Document and friends should have some helper
+  // functions to make this easier.
+
+  // use nsCopySupport::GetSelectionForCopy() ?
+  RefPtr<mozilla::dom::Selection> selection = GetDocumentSelection();
+  if (!selection) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (!mDocument) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsINode> bodyNode;
+  if (mDocument->IsHTMLOrXHTML()) {
+    // XXXbz why not just do GetBody() for all documents, then GetRootElement()
+    // if GetBody() is null?
+    bodyNode = mDocument->GetBody();
+  } else {
+    bodyNode = mDocument->GetRootElement();
+  }
+  if (!bodyNode) return NS_ERROR_FAILURE;
+
+  ErrorResult err;
+  selection->RemoveAllRanges(err);
+  if (err.Failed()) {
+    return err.StealNSResult();
+  }
+
+  mozilla::dom::Selection::AutoUserInitiated userSelection(selection);
+  selection->SelectAllChildren(*bodyNode, err);
+  return err.StealNSResult();
+}
+
+NS_IMETHODIMP nsDocumentViewer::CopySelection() {
+  RefPtr<PresShell> presShell = mPresShell;
+  nsCopySupport::FireClipboardEvent(eCopy, nsIClipboard::kGlobalClipboard,
+                                    presShell, nullptr);
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocumentViewer::CopyLinkLocation() {
+  NS_ENSURE_TRUE(mPresShell, NS_ERROR_NOT_INITIALIZED);
+  nsCOMPtr<nsINode> node = GetPopupLinkNode();
+  // make noise if we're not in a link
+  NS_ENSURE_TRUE(node, NS_ERROR_FAILURE);
+
+  nsCOMPtr<dom::Element> elm(do_QueryInterface(node));
+  NS_ENSURE_TRUE(elm, NS_ERROR_FAILURE);
+
+  nsAutoString locationText;
+  nsContentUtils::GetLinkLocation(elm, locationText);
+  if (locationText.IsEmpty()) return NS_ERROR_FAILURE;
+
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsIClipboardHelper> clipboard(
+      do_GetService("@mozilla.org/widget/clipboardhelper;1", &rv));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // copy the href onto the clipboard
+  return clipboard->CopyString(locationText);
+}
+
+NS_IMETHODIMP nsDocumentViewer::CopyImage(int32_t aCopyFlags) {
+  NS_ENSURE_TRUE(mPresShell, NS_ERROR_NOT_INITIALIZED);
+  nsCOMPtr<nsIImageLoadingContent> node = GetPopupImageNode();
+  // make noise if we're not in an image
+  NS_ENSURE_TRUE(node, NS_ERROR_FAILURE);
+
+  nsCOMPtr<nsILoadContext> loadContext(mContainer);
+  return nsCopySupport::ImageCopy(node, loadContext, aCopyFlags);
+}
+
+NS_IMETHODIMP nsDocumentViewer::GetCopyable(bool* aCopyable) {
+  NS_ENSURE_ARG_POINTER(aCopyable);
+  *aCopyable = nsCopySupport::CanCopy(mDocument);
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocumentViewer::GetContents(const char* mimeType,
+                                            bool selectionOnly,
+                                            nsAString& aOutValue) {
+  aOutValue.Truncate();
+
+  NS_ENSURE_TRUE(mPresShell, NS_ERROR_NOT_INITIALIZED);
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_NOT_INITIALIZED);
+
+  // Now we have the selection.  Make sure it's nonzero:
+  RefPtr<Selection> sel;
+  if (selectionOnly) {
+    sel = nsCopySupport::GetSelectionForCopy(mDocument);
+    NS_ENSURE_TRUE(sel, NS_ERROR_FAILURE);
+
+    if (sel->IsCollapsed()) {
+      return NS_OK;
+    }
+  }
+
+  // call the copy code
+  return nsCopySupport::GetContents(nsDependentCString(mimeType), 0, sel,
+                                    mDocument, aOutValue);
+}
+
+NS_IMETHODIMP nsDocumentViewer::GetCanGetContents(bool* aCanGetContents) {
+  NS_ENSURE_ARG_POINTER(aCanGetContents);
+  *aCanGetContents = false;
+  NS_ENSURE_STATE(mDocument);
+  *aCanGetContents = nsCopySupport::CanCopy(mDocument);
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocumentViewer::SetCommandNode(nsINode* aNode) {
+  Document* document = GetDocument();
+  NS_ENSURE_STATE(document);
+
+  nsCOMPtr<nsPIDOMWindowOuter> window(document->GetWindow());
+  NS_ENSURE_TRUE(window, NS_ERROR_NOT_AVAILABLE);
+
+  nsCOMPtr<nsPIWindowRoot> root = window->GetTopWindowRoot();
+  NS_ENSURE_STATE(root);
+
+  root->SetPopupNode(aNode);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetDeviceFullZoomForTest(float* aDeviceFullZoom) {
+  NS_ENSURE_ARG_POINTER(aDeviceFullZoom);
+  nsPresContext* pc = GetPresContext();
+  *aDeviceFullZoom = pc ? pc->GetDeviceFullZoom() : 1.0;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::SetAuthorStyleDisabled(bool aStyleDisabled) {
+  if (mPresShell) {
+    mPresShell->SetAuthorStyleDisabled(aStyleDisabled);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetAuthorStyleDisabled(bool* aStyleDisabled) {
+  if (mPresShell) {
+    *aStyleDisabled = mPresShell->GetAuthorStyleDisabled();
+  } else {
+    *aStyleDisabled = false;
+  }
+  return NS_OK;
+}
+
+/* [noscript,notxpcom] Encoding getHintCharset (); */
+NS_IMETHODIMP_(const Encoding*)
+nsDocumentViewer::GetReloadEncodingAndSource(int32_t* aSource) {
+  *aSource = mReloadEncodingSource;
+  if (kCharsetUninitialized == mReloadEncodingSource) {
+    return nullptr;
+  }
+  return mReloadEncoding;
+}
+
+NS_IMETHODIMP_(void)
+nsDocumentViewer::SetReloadEncodingAndSource(const Encoding* aEncoding,
+                                             int32_t aSource) {
+  MOZ_ASSERT(
+      aSource == kCharsetUninitialized ||
+      (aSource >=
+           kCharsetFromFinalAutoDetectionWouldHaveBeenUTF8InitialWasASCII &&
+       aSource <=
+           kCharsetFromFinalAutoDetectionWouldNotHaveBeenUTF8DependedOnTLDInitialWasASCII) ||
+      aSource == kCharsetFromFinalUserForcedAutoDetection);
+  mReloadEncoding = aEncoding;
+  mReloadEncodingSource = aSource;
+}
+
+NS_IMETHODIMP_(void)
+nsDocumentViewer::ForgetReloadEncoding() {
+  mReloadEncoding = nullptr;
+  mReloadEncodingSource = kCharsetUninitialized;
+}
+
+MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP nsDocumentViewer::GetContentSize(
+    int32_t aMaxWidth, int32_t aMaxHeight, int32_t aPrefWidth, int32_t* aWidth,
+    int32_t* aHeight) {
+  RefPtr<BrowsingContext> bc = mContainer->GetBrowsingContext();
+  NS_ENSURE_TRUE(bc, NS_ERROR_NOT_AVAILABLE);
+
+  // It's only valid to access this from a top frame.  Doesn't work from
+  // sub-frames.
+  NS_ENSURE_TRUE(bc->IsTop(), NS_ERROR_FAILURE);
+
+  // Convert max-width/height and pref-width to app units.
+  if (aMaxWidth > 0) {
+    aMaxWidth = CSSPixel::ToAppUnits(aMaxWidth);
+  } else {
+    aMaxWidth = NS_UNCONSTRAINEDSIZE;
+  }
+  if (aMaxHeight > 0) {
+    aMaxHeight = CSSPixel::ToAppUnits(aMaxHeight);
+  } else {
+    aMaxHeight = NS_UNCONSTRAINEDSIZE;
+  }
+  if (aPrefWidth > 0) {
+    aPrefWidth = CSSPixel::ToAppUnits(aPrefWidth);
+  } else {
+    aPrefWidth = 0;
+  }
+
+  RefPtr<PresShell> presShell = GetPresShell();
+  NS_ENSURE_TRUE(presShell, NS_ERROR_FAILURE);
+
+  // Flush out all content and style updates. We can't use a resize reflow
+  // because it won't change some sizes that a style change reflow will.
+  mDocument->FlushPendingNotifications(FlushType::Layout);
+
+  nsIFrame* root = presShell->GetRootFrame();
+  NS_ENSURE_TRUE(root, NS_ERROR_FAILURE);
+
+  WritingMode wm = root->GetWritingMode();
+
+  nscoord prefISize;
+  {
+    RefPtr<gfxContext> rcx(presShell->CreateReferenceRenderingContext());
+    nscoord maxISize = wm.IsVertical() ? aMaxHeight : aMaxWidth;
+    if (aPrefWidth) {
+      prefISize = std::max(root->GetMinISize(rcx), aPrefWidth);
+    } else {
+      prefISize = root->GetPrefISize(rcx);
+    }
+    prefISize = std::min(prefISize, maxISize);
+  }
+
+  // We should never intentionally get here with this sentinel value, but it's
+  // possible that a document with huge sizes might inadvertently have a
+  // prefISize that exactly matches NS_UNCONSTRAINEDSIZE.
+  // Just bail if that happens.
+  NS_ENSURE_TRUE(prefISize != NS_UNCONSTRAINEDSIZE, NS_ERROR_FAILURE);
+
+  nscoord height = wm.IsVertical() ? prefISize : aMaxHeight;
+  nscoord width = wm.IsVertical() ? aMaxWidth : prefISize;
+
+  presShell->ResizeReflow(width, height, ResizeReflowOptions::BSizeLimit);
+
+  RefPtr<nsPresContext> presContext = GetPresContext();
+  NS_ENSURE_TRUE(presContext, NS_ERROR_FAILURE);
+
+  // Protect against bogus returns here
+  nsRect shellArea = presContext->GetVisibleArea();
+  NS_ENSURE_TRUE(shellArea.width != NS_UNCONSTRAINEDSIZE &&
+                     shellArea.height != NS_UNCONSTRAINEDSIZE,
+                 NS_ERROR_FAILURE);
+
+  // Ceil instead of rounding here, so we can actually guarantee showing all the
+  // content.
+  *aWidth = std::ceil(CSSPixel::FromAppUnits(shellArea.width));
+  *aHeight = std::ceil(CSSPixel::FromAppUnits(shellArea.height));
+
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(nsDocViewerSelectionListener, nsISelectionListener)
+
+/*
+ * GetPopupNode, GetPopupLinkNode and GetPopupImageNode are helpers
+ * for the cmd_copyLink / cmd_copyImageLocation / cmd_copyImageContents family
+ * of commands. The focus controller stores the popup node, these retrieve
+ * them and munge appropriately. Note that we have to store the popup node
+ * rather than retrieving it from EventStateManager::GetFocusedContent because
+ * not all content (images included) can receive focus.
+ */
+
+already_AddRefed<nsINode> nsDocumentViewer::GetPopupNode() {
+  // get the document
+  Document* document = GetDocument();
+  NS_ENSURE_TRUE(document, nullptr);
+
+  // get the private dom window
+  nsCOMPtr<nsPIDOMWindowOuter> window(document->GetWindow());
+  NS_ENSURE_TRUE(window, nullptr);
+  if (window) {
+    nsCOMPtr<nsPIWindowRoot> root = window->GetTopWindowRoot();
+    NS_ENSURE_TRUE(root, nullptr);
+
+    // get the popup node
+    nsCOMPtr<nsINode> node = root->GetPopupNode();
+    if (!node) {
+      nsPIDOMWindowOuter* rootWindow = root->GetWindow();
+      if (rootWindow) {
+        nsCOMPtr<Document> rootDoc = rootWindow->GetExtantDoc();
+        if (rootDoc) {
+          nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+          if (pm) {
+            node = pm->GetLastTriggerPopupNode(rootDoc);
+          }
+        }
+      }
+    }
+    return node.forget();
+  }
+
+  return nullptr;
+}
+
+// GetPopupLinkNode: return popup link node or fail
+already_AddRefed<nsINode> nsDocumentViewer::GetPopupLinkNode() {
+  // find popup node
+  nsCOMPtr<nsINode> node = GetPopupNode();
+
+  // find out if we have a link in our ancestry
+  while (node) {
+    if (const auto* element = Element::FromNode(*node)) {
+      if (element->IsLink()) {
+        return node.forget();
+      }
+    }
+
+    // get our parent and keep trying...
+    node = node->GetParentNode();
+  }
+
+  // if we have no node, fail
+  return nullptr;
+}
+
+// GetPopupLinkNode: return popup image node or fail
+already_AddRefed<nsIImageLoadingContent> nsDocumentViewer::GetPopupImageNode() {
+  // find popup node
+  nsCOMPtr<nsINode> node = GetPopupNode();
+  nsCOMPtr<nsIImageLoadingContent> img = do_QueryInterface(node);
+  return img.forget();
+}
+
+/*
+ * XXX dr
+ * ------
+ * These two functions -- GetInLink and GetInImage -- are kind of annoying
+ * in that they only get called from the controller (in
+ * nsDOMWindowController::IsCommandEnabled). The actual construction of the
+ * context menus in communicator (nsContextMenu.js) has its own, redundant
+ * tests. No big deal, but good to keep in mind if we ever clean context
+ * menus.
+ */
+
+NS_IMETHODIMP nsDocumentViewer::GetInLink(bool* aInLink) {
+#ifdef DEBUG_dr
+  printf("dr :: nsDocumentViewer::GetInLink\n");
+#endif
+
+  NS_ENSURE_ARG_POINTER(aInLink);
+
+  // we're not in a link unless i say so
+  *aInLink = false;
+
+  // get the popup link
+  nsCOMPtr<nsINode> node = GetPopupLinkNode();
+  if (!node) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // if we made it here, we're in a link
+  *aInLink = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocumentViewer::GetInImage(bool* aInImage) {
+#ifdef DEBUG_dr
+  printf("dr :: nsDocumentViewer::GetInImage\n");
+#endif
+
+  NS_ENSURE_ARG_POINTER(aInImage);
+
+  // we're not in an image unless i say so
+  *aInImage = false;
+
+  // get the popup image
+  nsCOMPtr<nsIImageLoadingContent> node = GetPopupImageNode();
+  if (!node) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Make sure there is a URI assigned. This allows <input type="image"> to
+  // be an image but rejects other <input> types. This matches what
+  // nsContextMenu.js does.
+  nsCOMPtr<nsIURI> uri;
+  node->GetCurrentURI(getter_AddRefs(uri));
+  if (uri) {
+    // if we made it here, we're in an image
+    *aInImage = true;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocViewerSelectionListener::NotifySelectionChanged(
+    Document*, Selection*, int16_t aReason, int32_t aAmount) {
+  if (!mDocViewer) {
+    return NS_OK;
+  }
+
+  // get the selection state
+  RefPtr<mozilla::dom::Selection> selection =
+      mDocViewer->GetDocumentSelection();
+  if (!selection) {
+    return NS_ERROR_FAILURE;
+  }
+
+  Document* theDoc = mDocViewer->GetDocument();
+  if (!theDoc) return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsPIDOMWindowOuter> domWindow = theDoc->GetWindow();
+  if (!domWindow) return NS_ERROR_FAILURE;
+
+  bool selectionCollapsed = selection->IsCollapsed();
+  // We only call UpdateCommands when the selection changes from collapsed to
+  // non-collapsed or vice versa, however we skip the initializing collapse. We
+  // might need another update string for simple selection changes, but that
+  // would be expenseive.
+  if (mSelectionWasCollapsed != selectionCollapsed) {
+    domWindow->UpdateCommands(u"select"_ns, selection, aReason);
+    mSelectionWasCollapsed = selectionCollapsed;
+  }
+
+  return NS_OK;
+}
+
+// nsDocViewerFocusListener
+NS_IMPL_ISUPPORTS(nsDocViewerFocusListener, nsIDOMEventListener)
+
+nsresult nsDocViewerFocusListener::HandleEvent(Event* aEvent) {
+  NS_ENSURE_STATE(mDocViewer);
+
+  RefPtr<PresShell> presShell = mDocViewer->GetPresShell();
+  NS_ENSURE_TRUE(presShell, NS_ERROR_FAILURE);
+
+  RefPtr<nsFrameSelection> selection =
+      presShell->GetLastFocusedFrameSelection();
+  NS_ENSURE_TRUE(selection, NS_ERROR_FAILURE);
+  auto selectionStatus = selection->GetDisplaySelection();
+  nsAutoString eventType;
+  aEvent->GetType(eventType);
+  if (eventType.EqualsLiteral("focus")) {
+    // If selection was disabled, re-enable it.
+    if (selectionStatus == nsISelectionController::SELECTION_DISABLED ||
+        selectionStatus == nsISelectionController::SELECTION_HIDDEN) {
+      selection->SetDisplaySelection(nsISelectionController::SELECTION_ON);
+      selection->RepaintSelection(SelectionType::eNormal);
+    }
+  } else {
+    MOZ_ASSERT(eventType.EqualsLiteral("blur"), "Unexpected event type");
+    // If selection was on, disable it.
+    if (selectionStatus == nsISelectionController::SELECTION_ON ||
+        selectionStatus == nsISelectionController::SELECTION_ATTENTION) {
+      selection->SetDisplaySelection(
+          nsISelectionController::SELECTION_DISABLED);
+      selection->RepaintSelection(SelectionType::eNormal);
+    }
+  }
+
+  return NS_OK;
+}
+
+/** ---------------------------------------------------
+ *  From nsIWebBrowserPrint
+ */
+
+#ifdef NS_PRINTING
+
+NS_IMETHODIMP
+nsDocumentViewer::Print(nsIPrintSettings* aPrintSettings,
+                        RemotePrintJobChild* aRemotePrintJob,
+                        nsIWebProgressListener* aWebProgressListener) {
+  if (NS_WARN_IF(!mContainer)) {
+    PR_PL(("Container was destroyed yet we are still trying to use it!"));
+    return NS_ERROR_FAILURE;
+  }
+
+  if (NS_WARN_IF(!mDocument) || NS_WARN_IF(!mDeviceContext)) {
+    PR_PL(("Can't Print without a document and a device context"));
+    return NS_ERROR_FAILURE;
+  }
+
+  if (NS_WARN_IF(mPrintJob && mPrintJob->GetIsPrinting())) {
+    // If we are printing another URL, then exit.
+    // The reason we check here is because this method can be called while
+    // another is still in here (the printing dialog is a good example).  the
+    // only time we can print more than one job at a time is the regression
+    // tests.
+    nsresult rv = NS_ERROR_NOT_AVAILABLE;
+    RefPtr<nsPrintJob>(mPrintJob)->FirePrintingErrorEvent(rv);
+    return rv;
+  }
+
+  OnDonePrinting();
+
+  // Note: mContainer and mDocument are known to be non-null via null-checks
+  // earlier in this function.
+  // TODO(dholbert) Do we need to bother with this stack-owned local RefPtr?
+  // (Is there an edge case where it's needed to keep the nsPrintJob alive?)
+  RefPtr<nsPrintJob> printJob =
+      new nsPrintJob(*this, *mContainer, *mDocument,
+                     float(AppUnitsPerCSSInch()) /
+                         float(mDeviceContext->AppUnitsPerDevPixel()));
+  mPrintJob = printJob;
+
+  nsresult rv = printJob->Print(*mDocument, aPrintSettings, aRemotePrintJob,
+                                aWebProgressListener);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    OnDonePrinting();
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::PrintPreview(nsIPrintSettings* aPrintSettings,
+                               nsIWebProgressListener* aWebProgressListener,
+                               PrintPreviewResolver&& aCallback) {
+#  ifdef NS_PRINT_PREVIEW
+  RefPtr<Document> doc = mDocument.get();
+  NS_ENSURE_STATE(doc);
+
+  if (NS_WARN_IF(GetIsPrinting())) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsIDocShell> docShell(mContainer);
+  if (NS_WARN_IF(!docShell) || NS_WARN_IF(!mDeviceContext)) {
+    PR_PL(("Can't Print Preview without device context and docshell"));
+    return NS_ERROR_FAILURE;
+  }
+
+  NS_ENSURE_STATE(!GetIsPrinting());
+  // beforeprint event may have caused ContentViewer to be shutdown.
+  NS_ENSURE_STATE(mContainer);
+  NS_ENSURE_STATE(mDeviceContext);
+
+  OnDonePrinting();
+
+  // Note: mContainer and doc are known to be non-null via null-checks earlier
+  // in this function.
+  // TODO(dholbert) Do we need to bother with this stack-owned local RefPtr?
+  // (Is there an edge case where it's needed to keep the nsPrintJob alive?)
+  RefPtr<nsPrintJob> printJob =
+      new nsPrintJob(*this, *mContainer, *doc,
+                     float(AppUnitsPerCSSInch()) /
+                         float(mDeviceContext->AppUnitsPerDevPixel()));
+  mPrintJob = printJob;
+
+  nsresult rv = printJob->PrintPreview(
+      *doc, aPrintSettings, aWebProgressListener, std::move(aCallback));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    OnDonePrinting();
+  }
+  return rv;
+#  else
+  return NS_ERROR_FAILURE;
+#  endif  // NS_PRINT_PREVIEW
+}
+
+static const nsIFrame* GetTargetPageFrame(int32_t aTargetPageNum,
+                                          nsPageSequenceFrame* aSequenceFrame) {
+  MOZ_ASSERT(aTargetPageNum > 0 &&
+             aTargetPageNum <=
+                 aSequenceFrame->PrincipalChildList().GetLength());
+  return aSequenceFrame->PrincipalChildList().FrameAt(aTargetPageNum - 1);
+}
+
+// Calculate the scroll position where the center of |aFrame| is positioned at
+// the center of |aScrollable|'s scroll port for the print preview.
+// So what we do for that is;
+// 1) Calculate the position of the center of |aFrame| in the print preview
+//    coordinates.
+// 2) Reduce the half height of the scroll port from the result of 1.
+static nscoord ScrollPositionForFrame(const nsIFrame* aFrame,
+                                      nsIScrollableFrame* aScrollable,
+                                      float aPreviewScale) {
+  // Note that even if the computed scroll position is out of the range of
+  // the scroll port, it gets clamped in nsIScrollableFrame::ScrollTo.
+  return nscoord(aPreviewScale * aFrame->GetRect().Center().y -
+                 float(aScrollable->GetScrollPortRect().height) / 2.0f);
+}
+
+//----------------------------------------------------------------------
+NS_IMETHODIMP
+nsDocumentViewer::PrintPreviewScrollToPage(int16_t aType, int32_t aPageNum) {
+  if (!GetIsPrintPreview() || mPrintJob->GetIsCreatingPrintPreview())
+    return NS_ERROR_FAILURE;
+
+  nsIScrollableFrame* sf = mPresShell->GetRootScrollFrameAsScrollable();
+  if (!sf) return NS_OK;
+
+  auto [seqFrame, sheetCount] = mPrintJob->GetSeqFrameAndCountSheets();
+  Unused << sheetCount;
+  if (!seqFrame) {
+    return NS_ERROR_FAILURE;
+  }
+
+  float previewScale = seqFrame->GetPrintPreviewScale();
+
+  nsPoint dest = sf->GetScrollPosition();
+
+  switch (aType) {
+    case nsIWebBrowserPrint::PRINTPREVIEW_HOME:
+      dest.y = 0;
+      break;
+    case nsIWebBrowserPrint::PRINTPREVIEW_END:
+      dest.y = sf->GetScrollRange().YMost();
+      break;
+    case nsIWebBrowserPrint::PRINTPREVIEW_PREV_PAGE:
+    case nsIWebBrowserPrint::PRINTPREVIEW_NEXT_PAGE: {
+      auto [currentFrame, currentSheetNumber] = GetCurrentSheetFrameAndNumber();
+      Unused << currentSheetNumber;
+      if (!currentFrame) {
+        return NS_OK;
+      }
+
+      const nsIFrame* targetFrame = nullptr;
+      if (aType == nsIWebBrowserPrint::PRINTPREVIEW_PREV_PAGE) {
+        targetFrame = currentFrame->GetPrevInFlow();
+      } else {
+        targetFrame = currentFrame->GetNextInFlow();
+      }
+      if (!targetFrame) {
+        return NS_OK;
+      }
+
+      dest.y = ScrollPositionForFrame(targetFrame, sf, previewScale);
+      break;
+    }
+    case nsIWebBrowserPrint::PRINTPREVIEW_GOTO_PAGENUM: {
+      if (aPageNum <= 0 || aPageNum > sheetCount) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      const nsIFrame* targetFrame = GetTargetPageFrame(aPageNum, seqFrame);
+      MOZ_ASSERT(targetFrame);
+
+      dest.y = ScrollPositionForFrame(targetFrame, sf, previewScale);
+      break;
+    }
+    default:
+      return NS_ERROR_INVALID_ARG;
+      break;
+  }
+
+  sf->ScrollTo(dest, ScrollMode::Instant);
+
+  return NS_OK;
+}
+
+std::tuple<const nsIFrame*, int32_t>
+nsDocumentViewer::GetCurrentSheetFrameAndNumber() const {
+  MOZ_ASSERT(mPrintJob);
+  MOZ_ASSERT(GetIsPrintPreview() && !mPrintJob->GetIsCreatingPrintPreview());
+
+  // in PP mPrtPreview->mPrintObject->mSeqFrame is null
+  auto [seqFrame, sheetCount] = mPrintJob->GetSeqFrameAndCountSheets();
+  Unused << sheetCount;
+  if (!seqFrame) {
+    return {nullptr, 0};
+  }
+
+  nsIScrollableFrame* sf = mPresShell->GetRootScrollFrameAsScrollable();
+  if (!sf) {
+    // No scrollable contents, returns 1 even if there are multiple sheets.
+    return {seqFrame->PrincipalChildList().FirstChild(), 1};
+  }
+
+  nsPoint currentScrollPosition = sf->GetScrollPosition();
+  float halfwayPoint =
+      currentScrollPosition.y + float(sf->GetScrollPortRect().height) / 2.0f;
+  float lastDistanceFromHalfwayPoint = std::numeric_limits<float>::max();
+  int32_t sheetNumber = 0;
+  const nsIFrame* currentSheet = nullptr;
+  float previewScale = seqFrame->GetPrintPreviewScale();
+  for (const nsIFrame* sheetFrame : seqFrame->PrincipalChildList()) {
+    nsRect sheetRect = sheetFrame->GetRect();
+    sheetNumber++;
+    currentSheet = sheetFrame;
+
+    float bottomOfSheet = sheetRect.YMost() * previewScale;
+    if (bottomOfSheet < halfwayPoint) {
+      // If the bottom of the sheet is not yet over the halfway point, iterate
+      // the next frame to see if the next frame is over the halfway point and
+      // compare the distance from the halfway point.
+      lastDistanceFromHalfwayPoint = halfwayPoint - bottomOfSheet;
+      continue;
+    }
+
+    float topOfSheet = sheetRect.Y() * previewScale;
+    if (topOfSheet <= halfwayPoint) {
+      // If the top of the sheet is not yet over the halfway point or on the
+      // point, it's the current sheet.
+      break;
+    }
+
+    // Now the sheet rect is completely over the halfway point, compare the
+    // distances from the halfway point.
+    if ((topOfSheet - halfwayPoint) >= lastDistanceFromHalfwayPoint) {
+      // If the previous sheet distance is less than or equal to the current
+      // sheet distance, choose the previous one as the current.
+      sheetNumber--;
+      MOZ_ASSERT(sheetNumber > 0);
+      currentSheet = currentSheet->GetPrevInFlow();
+      MOZ_ASSERT(currentSheet);
+    }
+    break;
+  }
+
+  MOZ_ASSERT(sheetNumber <= sheetCount);
+  return {currentSheet, sheetNumber};
+}
+
+// XXXdholbert As noted in nsIWebBrowserPrint.idl, this API (the IDL attr
+// 'printPreviewCurrentPageNumber') is misnamed and needs s/Page/Sheet/.  See
+// bug 1669762.
+NS_IMETHODIMP
+nsDocumentViewer::GetPrintPreviewCurrentPageNumber(int32_t* aNumber) {
+  NS_ENSURE_ARG_POINTER(aNumber);
+  NS_ENSURE_TRUE(mPrintJob, NS_ERROR_FAILURE);
+  if (!GetIsPrintPreview() || mPrintJob->GetIsCreatingPrintPreview()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  auto [currentFrame, currentSheetNumber] = GetCurrentSheetFrameAndNumber();
+  Unused << currentFrame;
+  if (!currentSheetNumber) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aNumber = currentSheetNumber;
+
+  return NS_OK;
+}
+
+// XXX This always returns false for subdocuments
+NS_IMETHODIMP
+nsDocumentViewer::GetDoingPrint(bool* aDoingPrint) {
+  NS_ENSURE_ARG_POINTER(aDoingPrint);
+
+  // XXX shouldn't this be GetDoingPrint() ?
+  *aDoingPrint = mPrintJob ? mPrintJob->CreatedForPrintPreview() : false;
+  return NS_OK;
+}
+
+// XXX This always returns false for subdocuments
+NS_IMETHODIMP
+nsDocumentViewer::GetDoingPrintPreview(bool* aDoingPrintPreview) {
+  NS_ENSURE_ARG_POINTER(aDoingPrintPreview);
+
+  *aDoingPrintPreview = mPrintJob ? mPrintJob->CreatedForPrintPreview() : false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::ExitPrintPreview() {
+  NS_ENSURE_TRUE(mPrintJob, NS_ERROR_FAILURE);
+
+  if (GetIsPrinting()) {
+    // Block exiting the print preview window if we're in the middle of an
+    // actual print.
+    return NS_ERROR_FAILURE;
+  }
+
+  if (!GetIsPrintPreview()) {
+    NS_ERROR("Wow, we should never get here!");
+    return NS_OK;
+  }
+
+#  ifdef NS_PRINT_PREVIEW
+  mPrintJob->Destroy();
+  mPrintJob = nullptr;
+
+  // Since the print preview implementation discards the window that was used
+  // to show the print preview, we skip certain cleanup that we would otherwise
+  // want to do.  Specifically, we do not call `SetIsPrintPreview(false)` to
+  // unblock navigation, we do not call `SetOverrideDPPX` to reset the
+  // devicePixelRatio, and we do not call `Show` to make such changes take
+  // affect.
+#  endif  // NS_PRINT_PREVIEW
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetRawNumPages(int32_t* aRawNumPages) {
+  NS_ENSURE_ARG_POINTER(aRawNumPages);
+  NS_ENSURE_TRUE(mPrintJob, NS_ERROR_FAILURE);
+
+  *aRawNumPages = mPrintJob->GetRawNumPages();
+  return *aRawNumPages > 0 ? NS_OK : NS_ERROR_FAILURE;
+}
+
+// XXXdholbert As noted in nsIWebBrowserPrint.idl, this API (the IDL attr
+// 'printPreviewNumPages') is misnamed and needs s/Page/Sheet/.
+// See bug 1669762.
+NS_IMETHODIMP
+nsDocumentViewer::GetPrintPreviewNumPages(int32_t* aPrintPreviewNumPages) {
+  NS_ENSURE_ARG_POINTER(aPrintPreviewNumPages);
+  NS_ENSURE_TRUE(mPrintJob, NS_ERROR_FAILURE);
+  *aPrintPreviewNumPages = mPrintJob->GetPrintPreviewNumSheets();
+  return *aPrintPreviewNumPages > 0 ? NS_OK : NS_ERROR_FAILURE;
+}
+
+//----------------------------------------------------------------------------------
+// Printing/Print Preview Helpers
+//----------------------------------------------------------------------------------
+
+//----------------------------------------------------------------------------------
+// Walks the document tree and tells each DocShell whether Printing/PP is
+// happening
+#endif  // NS_PRINTING
+
+bool nsDocumentViewer::ShouldAttachToTopLevel() {
+  if (!mParentWidget) {
+    return false;
+  }
+
+  if (!mContainer) {
+    return false;
+  }
+
+  // We always attach when using puppet widgets
+  if (nsIWidget::UsePuppetWidgets()) {
+    return true;
+  }
+
+#if defined(XP_WIN) || defined(MOZ_WIDGET_GTK) || \
+    defined(MOZ_WIDGET_ANDROID) || defined(MOZ_WIDGET_UIKIT)
+  if (!mPresContext) {
+    return false;
+  }
+
+  // On windows, in the parent process we also attach, but just to
+  // chrome items
+  nsWindowType winType = mParentWidget->WindowType();
+  if ((winType == eWindowType_toplevel || winType == eWindowType_dialog ||
+       winType == eWindowType_invisible) &&
+      mPresContext->IsChrome()) {
+    return true;
+  }
+#endif
+
+  return false;
+}
+
+//------------------------------------------------------------
+// XXX this always returns false for subdocuments
+bool nsDocumentViewer::GetIsPrinting() const {
+#ifdef NS_PRINTING
+  if (mPrintJob) {
+    return mPrintJob->GetIsPrinting();
+  }
+#endif
+  return false;
+}
+
+//------------------------------------------------------------
+// The PrintJob holds the current value
+// this called from inside the DocViewer.
+// XXX it always returns false for subdocuments
+bool nsDocumentViewer::GetIsPrintPreview() const {
+#ifdef NS_PRINTING
+  return mPrintJob && mPrintJob->CreatedForPrintPreview();
+#else
+  return false;
+#endif
+}
+
+//------------------------------------------------------------
+// Notification from the PrintJob of the current PP status
+void nsDocumentViewer::SetIsPrintPreview(bool aIsPrintPreview) {
+  // Protect against pres shell destruction running scripts.
+  nsAutoScriptBlocker scriptBlocker;
+
+  if (!aIsPrintPreview) {
+    InvalidatePotentialSubDocDisplayItem();
+    if (mPresShell) {
+      DestroyPresShell();
+    }
+    mWindow = nullptr;
+    mViewManager = nullptr;
+    mPresContext = nullptr;
+    mPresShell = nullptr;
+  }
+}
+
+//----------------------------------------------------------------------------------
+// nsIDocumentViewerPrint IFace
+//----------------------------------------------------------------------------------
+
+//------------------------------------------------------------
+void nsDocumentViewer::IncrementDestroyBlockedCount() {
+  ++mDestroyBlockedCount;
+}
+
+void nsDocumentViewer::DecrementDestroyBlockedCount() {
+  --mDestroyBlockedCount;
+}
+
+//------------------------------------------------------------
+// This called ONLY when printing has completed and the DV
+// is being notified that it should get rid of the nsPrintJob.
+//
+// BUT, if we are in Print Preview then we want to ignore the
+// notification (we do not get rid of the nsPrintJob)
+//
+// One small caveat:
+//   This IS called from two places in this module for cleaning
+//   up when an error occurred during the start up printing
+//   and print preview
+//
+void nsDocumentViewer::OnDonePrinting() {
+#if defined(NS_PRINTING) && defined(NS_PRINT_PREVIEW)
+  // If Destroy() has been called during calling nsPrintJob::Print() or
+  // nsPrintJob::PrintPreview(), mPrintJob is already nullptr here.
+  // So, the following clean up does nothing in such case.
+  // (Do we need some of this for that case?)
+  if (mPrintJob) {
+    RefPtr<nsPrintJob> printJob = std::move(mPrintJob);
+    if (GetIsPrintPreview()) {
+      printJob->DestroyPrintingData();
+    } else {
+      printJob->Destroy();
+    }
+
+    // We are done printing, now clean up.
+    //
+    // For non-print-preview jobs, we are actually responsible for cleaning up
+    // our whole <browser> or window (see the OPEN_PRINT_BROWSER code), so gotta
+    // run window.close(), which will take care of this.
+    //
+    // For print preview jobs the front-end code is responsible for cleaning the
+    // UI.
+    if (!printJob->CreatedForPrintPreview()) {
+      if (mContainer) {
+        if (nsCOMPtr<nsPIDOMWindowOuter> win = mContainer->GetWindow()) {
+          win->Close();
+        }
+      }
+    } else if (mClosingWhilePrinting) {
+      if (mDocument) {
+        mDocument->Destroy();
+        mDocument = nullptr;
+      }
+      mClosingWhilePrinting = false;
+    }
+  }
+#endif  // NS_PRINTING && NS_PRINT_PREVIEW
+}
+
+NS_IMETHODIMP nsDocumentViewer::SetPrintSettingsForSubdocument(
+    nsIPrintSettings* aPrintSettings, RemotePrintJobChild* aRemotePrintJob) {
+#ifdef NS_PRINTING
+  {
+    nsAutoScriptBlocker scriptBlocker;
+
+    if (mPresShell) {
+      DestroyPresShell();
+    }
+
+    if (mPresContext) {
+      DestroyPresContext();
+    }
+
+    MOZ_ASSERT(!mPresContext);
+    MOZ_ASSERT(!mPresShell);
+
+    if (MOZ_UNLIKELY(!mDocument)) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    RefPtr<nsDeviceContextSpecProxy> devspec =
+        new nsDeviceContextSpecProxy(aRemotePrintJob);
+    nsresult rv = devspec->Init(aPrintSettings, /* aIsPrintPreview = */ true);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    mDeviceContext = new nsDeviceContext();
+    rv = mDeviceContext->InitForPrinting(devspec);
+
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    mPresContext = CreatePresContext(
+        mDocument, nsPresContext::eContext_PrintPreview, FindContainerView());
+    mPresContext->SetPrintSettings(aPrintSettings);
+    rv = mPresContext->Init(mDeviceContext);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = MakeWindow(nsSize(mPresContext->DevPixelsToAppUnits(mBounds.width),
+                           mPresContext->DevPixelsToAppUnits(mBounds.height)),
+                    FindContainerView());
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    MOZ_TRY(InitPresentationStuff(true));
+  }
+
+  RefPtr<PresShell> shell = mPresShell;
+  shell->FlushPendingNotifications(FlushType::Layout);
+#endif
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocumentViewer::SetPageModeForTesting(
+    bool aPageMode, nsIPrintSettings* aPrintSettings) {
+  // XXX Page mode is only partially working; it's currently used for
+  // reftests that require a paginated context
+  mIsPageMode = aPageMode;
+
+  // The DestroyPresShell call requires a script blocker, since the
+  // PresShell::Destroy call it does can cause scripts to run, which could
+  // re-entrantly call methods on the nsDocumentViewer.
+  nsAutoScriptBlocker scriptBlocker;
+
+  if (mPresShell) {
+    DestroyPresShell();
+  }
+
+  if (mPresContext) {
+    DestroyPresContext();
+  }
+
+  mViewManager = nullptr;
+  mWindow = nullptr;
+
+  NS_ENSURE_STATE(mDocument);
+  if (aPageMode) {
+    mPresContext = CreatePresContext(
+        mDocument, nsPresContext::eContext_PageLayout, FindContainerView());
+    NS_ENSURE_TRUE(mPresContext, NS_ERROR_OUT_OF_MEMORY);
+    mPresContext->SetPaginatedScrolling(true);
+    mPresContext->SetPrintSettings(aPrintSettings);
+    nsresult rv = mPresContext->Init(mDeviceContext);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+  NS_ENSURE_SUCCESS(InitInternal(mParentWidget, nullptr, nullptr, mBounds, true,
+                                 false, false),
+                    NS_ERROR_FAILURE);
+
+  Show();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetHistoryEntry(nsISHEntry** aHistoryEntry) {
+  NS_IF_ADDREF(*aHistoryEntry = mSHEntry);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetIsTabModalPromptAllowed(bool* aAllowed) {
+  *aAllowed = !mHidden;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::GetIsHidden(bool* aHidden) {
+  *aHidden = mHidden;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::SetIsHidden(bool aHidden) {
+  mHidden = aHidden;
+  return NS_OK;
+}
+
+void nsDocumentViewer::DestroyPresShell() {
+  // We assert this because destroying the pres shell could otherwise cause
+  // re-entrancy into nsDocumentViewer methods, and all callers of
+  // DestroyPresShell need to do other cleanup work afterwards before it
+  // is safe for those re-entrant method calls to be made.
+  MOZ_ASSERT(!nsContentUtils::IsSafeToRunScript(),
+             "DestroyPresShell must only be called when scripts are blocked");
+
+  // Break circular reference (or something)
+  mPresShell->EndObservingDocument();
+
+  RefPtr<mozilla::dom::Selection> selection = GetDocumentSelection();
+  if (selection && mSelectionListener)
+    selection->RemoveSelectionListener(mSelectionListener);
+
+  mPresShell->Destroy();
+  mPresShell = nullptr;
+}
+
+void nsDocumentViewer::InvalidatePotentialSubDocDisplayItem() {
+  if (mViewManager) {
+    if (nsView* rootView = mViewManager->GetRootView()) {
+      if (nsView* rootViewParent = rootView->GetParent()) {
+        if (nsView* subdocview = rootViewParent->GetParent()) {
+          if (nsIFrame* f = subdocview->GetFrame()) {
+            if (nsSubDocumentFrame* s = do_QueryFrame(f)) {
+              s->MarkNeedsDisplayItemRebuild();
+            }
+          }
+        }
+      }
+    }
+  }
+}
+
+void nsDocumentViewer::DestroyPresContext() {
+  InvalidatePotentialSubDocDisplayItem();
+  mPresContext = nullptr;
+}
+
+void nsDocumentViewer::SetPrintPreviewPresentation(nsViewManager* aViewManager,
+                                                   nsPresContext* aPresContext,
+                                                   PresShell* aPresShell) {
+  // Protect against pres shell destruction running scripts and re-entrantly
+  // creating a new presentation.
+  nsAutoScriptBlocker scriptBlocker;
+
+  if (mPresShell) {
+    DestroyPresShell();
+  }
+
+  mWindow = nullptr;
+  mViewManager = aViewManager;
+  mPresContext = aPresContext;
+  mPresShell = aPresShell;
+
+  if (ShouldAttachToTopLevel()) {
+    DetachFromTopLevelWidget();
+    nsView* rootView = mViewManager->GetRootView();
+    rootView->AttachToTopLevelWidget(mParentWidget);
+    mAttachedToParent = true;
+  }
+}
+
+// Fires the "document-shown" event so that interested parties are aware of it.
+NS_IMETHODIMP
+nsDocumentShownDispatcher::Run() {
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (observerService) {
+    observerService->NotifyObservers(ToSupports(mDocument), "document-shown",
+                                     nullptr);
+  }
+  return NS_OK;
+}