From 36d22d82aa202bb199967e9512281e9a53db42c9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 7 Apr 2024 21:33:14 +0200
Subject: Adding upstream version 115.7.0esr.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 dom/base/nsFocusManager.cpp | 5443 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 5443 insertions(+)
 create mode 100644 dom/base/nsFocusManager.cpp

(limited to 'dom/base/nsFocusManager.cpp')

diff --git a/dom/base/nsFocusManager.cpp b/dom/base/nsFocusManager.cpp
new file mode 100644
index 0000000000..ead05d9103
--- /dev/null
+++ b/dom/base/nsFocusManager.cpp
@@ -0,0 +1,5443 @@
+/* -*- 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/. */
+
+#include "mozilla/dom/BrowserParent.h"
+
+#include "nsFocusManager.h"
+
+#include "LayoutConstants.h"
+#include "ChildIterator.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsGkAtoms.h"
+#include "nsGlobalWindow.h"
+#include "nsContentUtils.h"
+#include "ContentParent.h"
+#include "nsPIDOMWindow.h"
+#include "nsIContentInlines.h"
+#include "nsIDocShell.h"
+#include "nsIDocShellTreeOwner.h"
+#include "nsIFormControl.h"
+#include "nsLayoutUtils.h"
+#include "nsFrameTraversal.h"
+#include "nsIWebNavigation.h"
+#include "nsCaret.h"
+#include "nsIBaseWindow.h"
+#include "nsIAppWindow.h"
+#include "nsTextControlFrame.h"
+#include "nsViewManager.h"
+#include "nsFrameSelection.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/Selection.h"
+#include "nsXULPopupManager.h"
+#include "nsMenuPopupFrame.h"
+#include "nsIScriptError.h"
+#include "nsIScriptObjectPrincipal.h"
+#include "nsIPrincipal.h"
+#include "nsIObserverService.h"
+#include "BrowserChild.h"
+#include "nsFrameLoader.h"
+#include "nsHTMLDocument.h"
+#include "nsNetUtil.h"
+#include "nsRange.h"
+#include "nsFrameLoaderOwner.h"
+#include "nsQueryObject.h"
+
+#include "mozilla/AccessibleCaretEventHub.h"
+#include "mozilla/ContentEvents.h"
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/ElementBinding.h"
+#include "mozilla/dom/HTMLImageElement.h"
+#include "mozilla/dom/HTMLInputElement.h"
+#include "mozilla/dom/HTMLSlotElement.h"
+#include "mozilla/dom/BrowserBridgeChild.h"
+#include "mozilla/dom/Text.h"
+#include "mozilla/dom/XULPopupElement.h"
+#include "mozilla/dom/WindowGlobalParent.h"
+#include "mozilla/dom/WindowGlobalChild.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/EventStateManager.h"
+#include "mozilla/HTMLEditor.h"
+#include "mozilla/IMEStateManager.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/PointerLockManager.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/Services.h"
+#include "mozilla/Unused.h"
+#include "mozilla/StaticPrefs_full_screen_api.h"
+#include <algorithm>
+
+#include "nsIDOMXULMenuListElement.h"
+
+#ifdef ACCESSIBILITY
+#  include "nsAccessibilityService.h"
+#endif
+
+using namespace mozilla;
+using namespace mozilla::dom;
+using namespace mozilla::widget;
+
+// Two types of focus pr logging are available:
+//   'Focus' for normal focus manager calls
+//   'FocusNavigation' for tab and document navigation
+LazyLogModule gFocusLog("Focus");
+LazyLogModule gFocusNavigationLog("FocusNavigation");
+
+#define LOGFOCUS(args) MOZ_LOG(gFocusLog, mozilla::LogLevel::Debug, args)
+#define LOGFOCUSNAVIGATION(args) \
+  MOZ_LOG(gFocusNavigationLog, mozilla::LogLevel::Debug, args)
+
+#define LOGTAG(log, format, content)                      \
+  if (MOZ_LOG_TEST(log, LogLevel::Debug)) {               \
+    nsAutoCString tag("(none)"_ns);                       \
+    if (content) {                                        \
+      content->NodeInfo()->NameAtom()->ToUTF8String(tag); \
+    }                                                     \
+    MOZ_LOG(log, LogLevel::Debug, (format, tag.get()));   \
+  }
+
+#define LOGCONTENT(format, content) LOGTAG(gFocusLog, format, content)
+#define LOGCONTENTNAVIGATION(format, content) \
+  LOGTAG(gFocusNavigationLog, format, content)
+
+struct nsDelayedBlurOrFocusEvent {
+  nsDelayedBlurOrFocusEvent(EventMessage aEventMessage, PresShell* aPresShell,
+                            Document* aDocument, EventTarget* aTarget,
+                            EventTarget* aRelatedTarget)
+      : mPresShell(aPresShell),
+        mDocument(aDocument),
+        mTarget(aTarget),
+        mEventMessage(aEventMessage),
+        mRelatedTarget(aRelatedTarget) {}
+
+  nsDelayedBlurOrFocusEvent(const nsDelayedBlurOrFocusEvent& aOther)
+      : mPresShell(aOther.mPresShell),
+        mDocument(aOther.mDocument),
+        mTarget(aOther.mTarget),
+        mEventMessage(aOther.mEventMessage) {}
+
+  RefPtr<PresShell> mPresShell;
+  nsCOMPtr<Document> mDocument;
+  nsCOMPtr<EventTarget> mTarget;
+  EventMessage mEventMessage;
+  nsCOMPtr<EventTarget> mRelatedTarget;
+};
+
+inline void ImplCycleCollectionUnlink(nsDelayedBlurOrFocusEvent& aField) {
+  aField.mPresShell = nullptr;
+  aField.mDocument = nullptr;
+  aField.mTarget = nullptr;
+  aField.mRelatedTarget = nullptr;
+}
+
+inline void ImplCycleCollectionTraverse(
+    nsCycleCollectionTraversalCallback& aCallback,
+    nsDelayedBlurOrFocusEvent& aField, const char* aName, uint32_t aFlags = 0) {
+  CycleCollectionNoteChild(
+      aCallback, static_cast<nsIDocumentObserver*>(aField.mPresShell.get()),
+      aName, aFlags);
+  CycleCollectionNoteChild(aCallback, aField.mDocument.get(), aName, aFlags);
+  CycleCollectionNoteChild(aCallback, aField.mTarget.get(), aName, aFlags);
+  CycleCollectionNoteChild(aCallback, aField.mRelatedTarget.get(), aName,
+                           aFlags);
+}
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsFocusManager)
+  NS_INTERFACE_MAP_ENTRY(nsIFocusManager)
+  NS_INTERFACE_MAP_ENTRY(nsIObserver)
+  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIFocusManager)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsFocusManager)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsFocusManager)
+
+NS_IMPL_CYCLE_COLLECTION_WEAK(nsFocusManager, mActiveWindow,
+                              mActiveBrowsingContextInContent,
+                              mActiveBrowsingContextInChrome, mFocusedWindow,
+                              mFocusedBrowsingContextInContent,
+                              mFocusedBrowsingContextInChrome, mFocusedElement,
+                              mFirstBlurEvent, mFirstFocusEvent,
+                              mWindowBeingLowered, mDelayedBlurFocusEvents)
+
+StaticRefPtr<nsFocusManager> nsFocusManager::sInstance;
+bool nsFocusManager::sTestMode = false;
+uint64_t nsFocusManager::sFocusActionCounter = 0;
+
+static const char* kObservedPrefs[] = {"accessibility.browsewithcaret",
+                                       "accessibility.tabfocus_applies_to_xul",
+                                       "focusmanager.testmode", nullptr};
+
+nsFocusManager::nsFocusManager()
+    : mActionIdForActiveBrowsingContextInContent(0),
+      mActionIdForActiveBrowsingContextInChrome(0),
+      mActionIdForFocusedBrowsingContextInContent(0),
+      mActionIdForFocusedBrowsingContextInChrome(0),
+      mActiveBrowsingContextInContentSetFromOtherProcess(false),
+      mEventHandlingNeedsFlush(false) {}
+
+nsFocusManager::~nsFocusManager() {
+  Preferences::UnregisterCallbacks(nsFocusManager::PrefChanged, kObservedPrefs,
+                                   this);
+
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (obs) {
+    obs->RemoveObserver(this, "xpcom-shutdown");
+  }
+}
+
+// static
+nsresult nsFocusManager::Init() {
+  sInstance = new nsFocusManager();
+
+  nsIContent::sTabFocusModelAppliesToXUL =
+      Preferences::GetBool("accessibility.tabfocus_applies_to_xul",
+                           nsIContent::sTabFocusModelAppliesToXUL);
+
+  sTestMode = Preferences::GetBool("focusmanager.testmode", false);
+
+  Preferences::RegisterCallbacks(nsFocusManager::PrefChanged, kObservedPrefs,
+                                 sInstance.get());
+
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (obs) {
+    obs->AddObserver(sInstance, "xpcom-shutdown", true);
+  }
+
+  return NS_OK;
+}
+
+// static
+void nsFocusManager::Shutdown() { sInstance = nullptr; }
+
+// static
+void nsFocusManager::PrefChanged(const char* aPref, void* aSelf) {
+  if (RefPtr<nsFocusManager> fm = static_cast<nsFocusManager*>(aSelf)) {
+    fm->PrefChanged(aPref);
+  }
+}
+
+void nsFocusManager::PrefChanged(const char* aPref) {
+  nsDependentCString pref(aPref);
+  if (pref.EqualsLiteral("accessibility.browsewithcaret")) {
+    UpdateCaretForCaretBrowsingMode();
+  } else if (pref.EqualsLiteral("accessibility.tabfocus_applies_to_xul")) {
+    nsIContent::sTabFocusModelAppliesToXUL =
+        Preferences::GetBool("accessibility.tabfocus_applies_to_xul",
+                             nsIContent::sTabFocusModelAppliesToXUL);
+  } else if (pref.EqualsLiteral("focusmanager.testmode")) {
+    sTestMode = Preferences::GetBool("focusmanager.testmode", false);
+  }
+}
+
+NS_IMETHODIMP
+nsFocusManager::Observe(nsISupports* aSubject, const char* aTopic,
+                        const char16_t* aData) {
+  if (!nsCRT::strcmp(aTopic, "xpcom-shutdown")) {
+    mActiveWindow = nullptr;
+    mActiveBrowsingContextInContent = nullptr;
+    mActionIdForActiveBrowsingContextInContent = 0;
+    mActionIdForFocusedBrowsingContextInContent = 0;
+    mActiveBrowsingContextInChrome = nullptr;
+    mActionIdForActiveBrowsingContextInChrome = 0;
+    mActionIdForFocusedBrowsingContextInChrome = 0;
+    mFocusedWindow = nullptr;
+    mFocusedBrowsingContextInContent = nullptr;
+    mFocusedBrowsingContextInChrome = nullptr;
+    mFocusedElement = nullptr;
+    mFirstBlurEvent = nullptr;
+    mFirstFocusEvent = nullptr;
+    mWindowBeingLowered = nullptr;
+    mDelayedBlurFocusEvents.Clear();
+  }
+
+  return NS_OK;
+}
+
+static bool ActionIdComparableAndLower(uint64_t aActionId,
+                                       uint64_t aReference) {
+  MOZ_ASSERT(aActionId, "Uninitialized action id");
+  auto [actionProc, actionId] =
+      nsContentUtils::SplitProcessSpecificId(aActionId);
+  auto [refProc, refId] = nsContentUtils::SplitProcessSpecificId(aReference);
+  return actionProc == refProc && actionId < refId;
+}
+
+// given a frame content node, retrieve the nsIDOMWindow displayed in it
+static nsPIDOMWindowOuter* GetContentWindow(nsIContent* aContent) {
+  Document* doc = aContent->GetComposedDoc();
+  if (doc) {
+    Document* subdoc = doc->GetSubDocumentFor(aContent);
+    if (subdoc) {
+      return subdoc->GetWindow();
+    }
+  }
+
+  return nullptr;
+}
+
+bool nsFocusManager::IsFocused(nsIContent* aContent) {
+  if (!aContent || !mFocusedElement) {
+    return false;
+  }
+  return aContent == mFocusedElement;
+}
+
+bool nsFocusManager::IsTestMode() { return sTestMode; }
+
+bool nsFocusManager::IsInActiveWindow(BrowsingContext* aBC) const {
+  RefPtr<BrowsingContext> top = aBC->Top();
+  if (XRE_IsParentProcess()) {
+    top = top->Canonical()->TopCrossChromeBoundary();
+  }
+  return IsSameOrAncestor(top, GetActiveBrowsingContext());
+}
+
+// get the current window for the given content node
+static nsPIDOMWindowOuter* GetCurrentWindow(nsIContent* aContent) {
+  Document* doc = aContent->GetComposedDoc();
+  return doc ? doc->GetWindow() : nullptr;
+}
+
+// static
+Element* nsFocusManager::GetFocusedDescendant(
+    nsPIDOMWindowOuter* aWindow, SearchRange aSearchRange,
+    nsPIDOMWindowOuter** aFocusedWindow) {
+  NS_ENSURE_TRUE(aWindow, nullptr);
+
+  *aFocusedWindow = nullptr;
+
+  Element* currentElement = nullptr;
+  nsPIDOMWindowOuter* window = aWindow;
+  for (;;) {
+    *aFocusedWindow = window;
+    currentElement = window->GetFocusedElement();
+    if (!currentElement || aSearchRange == eOnlyCurrentWindow) {
+      break;
+    }
+
+    window = GetContentWindow(currentElement);
+    if (!window) {
+      break;
+    }
+
+    if (aSearchRange == eIncludeAllDescendants) {
+      continue;
+    }
+
+    MOZ_ASSERT(aSearchRange == eIncludeVisibleDescendants);
+
+    // If the child window doesn't have PresShell, it means the window is
+    // invisible.
+    nsIDocShell* docShell = window->GetDocShell();
+    if (!docShell) {
+      break;
+    }
+    if (!docShell->GetPresShell()) {
+      break;
+    }
+  }
+
+  NS_IF_ADDREF(*aFocusedWindow);
+
+  return currentElement;
+}
+
+// static
+InputContextAction::Cause nsFocusManager::GetFocusMoveActionCause(
+    uint32_t aFlags) {
+  if (aFlags & nsIFocusManager::FLAG_BYTOUCH) {
+    return InputContextAction::CAUSE_TOUCH;
+  } else if (aFlags & nsIFocusManager::FLAG_BYMOUSE) {
+    return InputContextAction::CAUSE_MOUSE;
+  } else if (aFlags & nsIFocusManager::FLAG_BYKEY) {
+    return InputContextAction::CAUSE_KEY;
+  } else if (aFlags & nsIFocusManager::FLAG_BYLONGPRESS) {
+    return InputContextAction::CAUSE_LONGPRESS;
+  }
+  return InputContextAction::CAUSE_UNKNOWN;
+}
+
+NS_IMETHODIMP
+nsFocusManager::GetActiveWindow(mozIDOMWindowProxy** aWindow) {
+  MOZ_ASSERT(XRE_IsParentProcess(),
+             "Must not be called outside the parent process.");
+  NS_IF_ADDREF(*aWindow = mActiveWindow);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsFocusManager::GetActiveBrowsingContext(BrowsingContext** aBrowsingContext) {
+  NS_IF_ADDREF(*aBrowsingContext = GetActiveBrowsingContext());
+  return NS_OK;
+}
+
+void nsFocusManager::FocusWindow(nsPIDOMWindowOuter* aWindow,
+                                 CallerType aCallerType) {
+  if (RefPtr<nsFocusManager> fm = sInstance) {
+    fm->SetFocusedWindowWithCallerType(aWindow, aCallerType);
+  }
+}
+
+NS_IMETHODIMP
+nsFocusManager::GetFocusedWindow(mozIDOMWindowProxy** aFocusedWindow) {
+  NS_IF_ADDREF(*aFocusedWindow = mFocusedWindow);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsFocusManager::GetFocusedContentBrowsingContext(
+    BrowsingContext** aBrowsingContext) {
+  MOZ_DIAGNOSTIC_ASSERT(
+      XRE_IsParentProcess(),
+      "We only have use cases for this in the parent process");
+  NS_IF_ADDREF(*aBrowsingContext = GetFocusedBrowsingContextInChrome());
+  return NS_OK;
+}
+
+nsresult nsFocusManager::SetFocusedWindowWithCallerType(
+    mozIDOMWindowProxy* aWindowToFocus, CallerType aCallerType) {
+  LOGFOCUS(("<<SetFocusedWindow begin>>"));
+
+  nsCOMPtr<nsPIDOMWindowOuter> windowToFocus =
+      nsPIDOMWindowOuter::From(aWindowToFocus);
+  NS_ENSURE_TRUE(windowToFocus, NS_ERROR_FAILURE);
+
+  nsCOMPtr<Element> frameElement = windowToFocus->GetFrameElementInternal();
+  Maybe<uint64_t> actionIdFromSetFocusInner;
+  if (frameElement) {
+    // pass false for aFocusChanged so that the caret does not get updated
+    // and scrolling does not occur.
+    actionIdFromSetFocusInner = SetFocusInner(frameElement, 0, false, true);
+  } else {
+    // this is a top-level window. If the window has a child frame focused,
+    // clear the focus. Otherwise, focus should already be in this frame, or
+    // already cleared. This ensures that focus will be in this frame and not
+    // in a child.
+    nsIContent* content = windowToFocus->GetFocusedElement();
+    if (content) {
+      if (nsCOMPtr<nsPIDOMWindowOuter> childWindow = GetContentWindow(content))
+        ClearFocus(windowToFocus);
+    }
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> rootWindow = windowToFocus->GetPrivateRoot();
+  const uint64_t actionId = actionIdFromSetFocusInner.isSome()
+                                ? actionIdFromSetFocusInner.value()
+                                : sInstance->GenerateFocusActionId();
+  if (rootWindow) {
+    RaiseWindow(rootWindow, aCallerType, actionId);
+  }
+
+  LOGFOCUS(("<<SetFocusedWindow end actionid: %" PRIu64 ">>", actionId));
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsFocusManager::SetFocusedWindow(
+    mozIDOMWindowProxy* aWindowToFocus) {
+  return SetFocusedWindowWithCallerType(aWindowToFocus, CallerType::System);
+}
+
+NS_IMETHODIMP
+nsFocusManager::GetFocusedElement(Element** aFocusedElement) {
+  RefPtr<Element> focusedElement = mFocusedElement;
+  focusedElement.forget(aFocusedElement);
+  return NS_OK;
+}
+
+uint32_t nsFocusManager::GetLastFocusMethod(nsPIDOMWindowOuter* aWindow) const {
+  nsPIDOMWindowOuter* window = aWindow ? aWindow : mFocusedWindow.get();
+  uint32_t method = window ? window->GetFocusMethod() : 0;
+  NS_ASSERTION((method & METHOD_MASK) == method, "invalid focus method");
+  return method;
+}
+
+NS_IMETHODIMP
+nsFocusManager::GetLastFocusMethod(mozIDOMWindowProxy* aWindow,
+                                   uint32_t* aLastFocusMethod) {
+  *aLastFocusMethod = GetLastFocusMethod(nsPIDOMWindowOuter::From(aWindow));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsFocusManager::SetFocus(Element* aElement, uint32_t aFlags) {
+  LOGFOCUS(("<<SetFocus begin>>"));
+
+  NS_ENSURE_ARG(aElement);
+
+  SetFocusInner(aElement, aFlags, true, true);
+
+  LOGFOCUS(("<<SetFocus end>>"));
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsFocusManager::ElementIsFocusable(Element* aElement, uint32_t aFlags,
+                                   bool* aIsFocusable) {
+  NS_ENSURE_TRUE(aElement, NS_ERROR_INVALID_ARG);
+  *aIsFocusable = !!FlushAndCheckIfFocusable(aElement, aFlags);
+  return NS_OK;
+}
+
+MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP
+nsFocusManager::MoveFocus(mozIDOMWindowProxy* aWindow, Element* aStartElement,
+                          uint32_t aType, uint32_t aFlags, Element** aElement) {
+  *aElement = nullptr;
+
+  LOGFOCUS(("<<MoveFocus begin Type: %d Flags: %x>>", aType, aFlags));
+
+  if (MOZ_LOG_TEST(gFocusLog, LogLevel::Debug) && mFocusedWindow) {
+    Document* doc = mFocusedWindow->GetExtantDoc();
+    if (doc && doc->GetDocumentURI()) {
+      LOGFOCUS((" Focused Window: %p %s", mFocusedWindow.get(),
+                doc->GetDocumentURI()->GetSpecOrDefault().get()));
+    }
+  }
+
+  LOGCONTENT("  Current Focus: %s", mFocusedElement.get());
+
+  // use FLAG_BYMOVEFOCUS when switching focus with MoveFocus unless one of
+  // the other focus methods is already set, or we're just moving to the root
+  // or caret position.
+  if (aType != MOVEFOCUS_ROOT && aType != MOVEFOCUS_CARET &&
+      (aFlags & METHOD_MASK) == 0) {
+    aFlags |= FLAG_BYMOVEFOCUS;
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> window;
+  if (aStartElement) {
+    window = GetCurrentWindow(aStartElement);
+  } else {
+    window = aWindow ? nsPIDOMWindowOuter::From(aWindow) : mFocusedWindow.get();
+  }
+
+  NS_ENSURE_TRUE(window, NS_ERROR_FAILURE);
+
+  // Flush to ensure that focusability of descendants is computed correctly.
+  if (RefPtr<Document> doc = window->GetExtantDoc()) {
+    doc->FlushPendingNotifications(FlushType::EnsurePresShellInitAndFrames);
+  }
+
+  bool noParentTraversal = aFlags & FLAG_NOPARENTFRAME;
+  nsCOMPtr<nsIContent> newFocus;
+  nsresult rv = DetermineElementToMoveFocus(window, aStartElement, aType,
+                                            noParentTraversal, true,
+                                            getter_AddRefs(newFocus));
+  if (rv == NS_SUCCESS_DOM_NO_OPERATION) {
+    return NS_OK;
+  }
+
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  LOGCONTENTNAVIGATION("Element to be focused: %s", newFocus.get());
+
+  if (newFocus && newFocus->IsElement()) {
+    // for caret movement, pass false for the aFocusChanged argument,
+    // otherwise the caret will end up moving to the focus position. This
+    // would be a problem because the caret would move to the beginning of the
+    // focused link making it impossible to navigate the caret over a link.
+    SetFocusInner(MOZ_KnownLive(newFocus->AsElement()), aFlags,
+                  aType != MOVEFOCUS_CARET, true);
+    *aElement = do_AddRef(newFocus->AsElement()).take();
+  } else if (aType == MOVEFOCUS_ROOT || aType == MOVEFOCUS_CARET) {
+    // no content was found, so clear the focus for these two types.
+    ClearFocus(window);
+  }
+
+  LOGFOCUS(("<<MoveFocus end>>"));
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsFocusManager::ClearFocus(mozIDOMWindowProxy* aWindow) {
+  LOGFOCUS(("<<ClearFocus begin>>"));
+
+  // if the window to clear is the focused window or an ancestor of the
+  // focused window, then blur the existing focused content. Otherwise, the
+  // focus is somewhere else so just update the current node.
+  NS_ENSURE_TRUE(aWindow, NS_ERROR_INVALID_ARG);
+  nsCOMPtr<nsPIDOMWindowOuter> window = nsPIDOMWindowOuter::From(aWindow);
+
+  if (IsSameOrAncestor(window, GetFocusedBrowsingContext())) {
+    RefPtr<BrowsingContext> bc = window->GetBrowsingContext();
+    bool isAncestor = (GetFocusedBrowsingContext() != bc);
+    uint64_t actionId = GenerateFocusActionId();
+    if (Blur(bc, nullptr, isAncestor, true, false, actionId)) {
+      // if we are clearing the focus on an ancestor of the focused window,
+      // the ancestor will become the new focused window, so focus it
+      if (isAncestor) {
+        Focus(window, nullptr, 0, true, false, false, true, actionId);
+      }
+    }
+  } else {
+    window->SetFocusedElement(nullptr);
+  }
+
+  LOGFOCUS(("<<ClearFocus end>>"));
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsFocusManager::GetFocusedElementForWindow(mozIDOMWindowProxy* aWindow,
+                                           bool aDeep,
+                                           mozIDOMWindowProxy** aFocusedWindow,
+                                           Element** aElement) {
+  *aElement = nullptr;
+  if (aFocusedWindow) {
+    *aFocusedWindow = nullptr;
+  }
+
+  NS_ENSURE_TRUE(aWindow, NS_ERROR_INVALID_ARG);
+  nsCOMPtr<nsPIDOMWindowOuter> window = nsPIDOMWindowOuter::From(aWindow);
+
+  nsCOMPtr<nsPIDOMWindowOuter> focusedWindow;
+  RefPtr<Element> focusedElement =
+      GetFocusedDescendant(window,
+                           aDeep ? nsFocusManager::eIncludeAllDescendants
+                                 : nsFocusManager::eOnlyCurrentWindow,
+                           getter_AddRefs(focusedWindow));
+
+  focusedElement.forget(aElement);
+
+  if (aFocusedWindow) {
+    NS_IF_ADDREF(*aFocusedWindow = focusedWindow);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsFocusManager::MoveCaretToFocus(mozIDOMWindowProxy* aWindow) {
+  nsCOMPtr<nsIWebNavigation> webnav = do_GetInterface(aWindow);
+  nsCOMPtr<nsIDocShellTreeItem> dsti = do_QueryInterface(webnav);
+  if (dsti) {
+    if (dsti->ItemType() != nsIDocShellTreeItem::typeChrome) {
+      nsCOMPtr<nsIDocShell> docShell = do_QueryInterface(dsti);
+      NS_ENSURE_TRUE(docShell, NS_ERROR_FAILURE);
+
+      // don't move the caret for editable documents
+      bool isEditable;
+      docShell->GetEditable(&isEditable);
+      if (isEditable) {
+        return NS_OK;
+      }
+
+      RefPtr<PresShell> presShell = docShell->GetPresShell();
+      NS_ENSURE_TRUE(presShell, NS_ERROR_FAILURE);
+
+      nsCOMPtr<nsPIDOMWindowOuter> window = nsPIDOMWindowOuter::From(aWindow);
+      if (RefPtr<Element> focusedElement = window->GetFocusedElement()) {
+        MoveCaretToFocus(presShell, focusedElement);
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+void nsFocusManager::WindowRaised(mozIDOMWindowProxy* aWindow,
+                                  uint64_t aActionId) {
+  if (!aWindow) {
+    return;
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> window = nsPIDOMWindowOuter::From(aWindow);
+  BrowsingContext* bc = window->GetBrowsingContext();
+
+  if (MOZ_LOG_TEST(gFocusLog, LogLevel::Debug)) {
+    LOGFOCUS(("Window %p Raised [Currently: %p %p] actionid: %" PRIu64, aWindow,
+              mActiveWindow.get(), mFocusedWindow.get(), aActionId));
+    Document* doc = window->GetExtantDoc();
+    if (doc && doc->GetDocumentURI()) {
+      LOGFOCUS(("  Raised Window: %p %s", aWindow,
+                doc->GetDocumentURI()->GetSpecOrDefault().get()));
+    }
+    if (mActiveWindow) {
+      doc = mActiveWindow->GetExtantDoc();
+      if (doc && doc->GetDocumentURI()) {
+        LOGFOCUS(("  Active Window: %p %s", mActiveWindow.get(),
+                  doc->GetDocumentURI()->GetSpecOrDefault().get()));
+      }
+    }
+  }
+
+  if (XRE_IsParentProcess()) {
+    if (mActiveWindow == window) {
+      // The window is already active, so there is no need to focus anything,
+      // but make sure that the right widget is focused. This is a special case
+      // for Windows because when restoring a minimized window, a second
+      // activation will occur and the top-level widget could be focused instead
+      // of the child we want. We solve this by calling SetFocus to ensure that
+      // what the focus manager thinks should be the current widget is actually
+      // focused.
+      EnsureCurrentWidgetFocused(CallerType::System);
+      return;
+    }
+
+    // lower the existing window, if any. This shouldn't happen usually.
+    if (nsCOMPtr<nsPIDOMWindowOuter> activeWindow = mActiveWindow) {
+      WindowLowered(activeWindow, aActionId);
+    }
+  } else if (bc->IsTop()) {
+    BrowsingContext* active = GetActiveBrowsingContext();
+    if (active == bc && !mActiveBrowsingContextInContentSetFromOtherProcess) {
+      // EnsureCurrentWidgetFocused() should not be necessary with
+      // PuppetWidget.
+      return;
+    }
+
+    if (active && active != bc) {
+      if (active->IsInProcess()) {
+        nsCOMPtr<nsPIDOMWindowOuter> activeWindow = active->GetDOMWindow();
+        WindowLowered(activeWindow, aActionId);
+      }
+      // No else, because trying to lower other-process windows
+      // from here can result in the BrowsingContext no longer
+      // existing in the parent process by the time it deserializes
+      // the IPC message.
+    }
+  }
+
+  nsCOMPtr<nsIDocShellTreeItem> docShellAsItem = window->GetDocShell();
+  // If there's no docShellAsItem, this window must have been closed,
+  // in that case there is no tree owner.
+  if (!docShellAsItem) {
+    return;
+  }
+
+  // set this as the active window
+  if (XRE_IsParentProcess()) {
+    mActiveWindow = window;
+  } else if (bc->IsTop()) {
+    SetActiveBrowsingContextInContent(bc, aActionId);
+  }
+
+  // ensure that the window is enabled and visible
+  nsCOMPtr<nsIDocShellTreeOwner> treeOwner;
+  docShellAsItem->GetTreeOwner(getter_AddRefs(treeOwner));
+  nsCOMPtr<nsIBaseWindow> baseWindow = do_QueryInterface(treeOwner);
+  if (baseWindow) {
+    bool isEnabled = true;
+    if (NS_SUCCEEDED(baseWindow->GetEnabled(&isEnabled)) && !isEnabled) {
+      return;
+    }
+
+    baseWindow->SetVisibility(true);
+  }
+
+  if (XRE_IsParentProcess()) {
+    // Unsetting top-level focus upon lowering was inhibited to accommodate
+    // ATOK, so we need to do it here.
+    BrowserParent::UnsetTopLevelWebFocusAll();
+    ActivateOrDeactivate(window, true);
+  }
+
+  // retrieve the last focused element within the window that was raised
+  nsCOMPtr<nsPIDOMWindowOuter> currentWindow;
+  RefPtr<Element> currentFocus = GetFocusedDescendant(
+      window, eIncludeAllDescendants, getter_AddRefs(currentWindow));
+
+  NS_ASSERTION(currentWindow, "window raised with no window current");
+  if (!currentWindow) {
+    return;
+  }
+
+  nsCOMPtr<nsIAppWindow> appWin(do_GetInterface(baseWindow));
+  // We use mFocusedWindow here is basically for the case that iframe navigate
+  // from a.com to b.com for example, so it ends up being loaded in a different
+  // process after Fission, but
+  // currentWindow->GetBrowsingContext() == GetFocusedBrowsingContext() would
+  // still be true because focused browsing context is synced, and we won't
+  // fire a focus event while focusing if we use it as condition.
+  Focus(currentWindow, currentFocus, 0, currentWindow != mFocusedWindow, false,
+        appWin != nullptr, true, aActionId);
+}
+
+void nsFocusManager::WindowLowered(mozIDOMWindowProxy* aWindow,
+                                   uint64_t aActionId) {
+  if (!aWindow) {
+    return;
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> window = nsPIDOMWindowOuter::From(aWindow);
+
+  if (MOZ_LOG_TEST(gFocusLog, LogLevel::Debug)) {
+    LOGFOCUS(("Window %p Lowered [Currently: %p %p]", aWindow,
+              mActiveWindow.get(), mFocusedWindow.get()));
+    Document* doc = window->GetExtantDoc();
+    if (doc && doc->GetDocumentURI()) {
+      LOGFOCUS(("  Lowered Window: %s",
+                doc->GetDocumentURI()->GetSpecOrDefault().get()));
+    }
+    if (mActiveWindow) {
+      doc = mActiveWindow->GetExtantDoc();
+      if (doc && doc->GetDocumentURI()) {
+        LOGFOCUS(("  Active Window: %s",
+                  doc->GetDocumentURI()->GetSpecOrDefault().get()));
+      }
+    }
+  }
+
+  if (XRE_IsParentProcess()) {
+    if (mActiveWindow != window) {
+      return;
+    }
+  } else {
+    BrowsingContext* bc = window->GetBrowsingContext();
+    BrowsingContext* active = GetActiveBrowsingContext();
+    if (active != bc->Top()) {
+      return;
+    }
+  }
+
+  // clear the mouse capture as the active window has changed
+  PresShell::ReleaseCapturingContent();
+
+  // In addition, reset the drag state to ensure that we are no longer in
+  // drag-select mode.
+  if (mFocusedWindow) {
+    nsCOMPtr<nsIDocShell> docShell = mFocusedWindow->GetDocShell();
+    if (docShell) {
+      if (PresShell* presShell = docShell->GetPresShell()) {
+        RefPtr<nsFrameSelection> frameSelection = presShell->FrameSelection();
+        frameSelection->SetDragState(false);
+      }
+    }
+  }
+
+  if (XRE_IsParentProcess()) {
+    ActivateOrDeactivate(window, false);
+  }
+
+  // keep track of the window being lowered, so that attempts to raise the
+  // window can be prevented until we return. Otherwise, focus can get into
+  // an unusual state.
+  mWindowBeingLowered = window;
+  if (XRE_IsParentProcess()) {
+    mActiveWindow = nullptr;
+  } else {
+    BrowsingContext* bc = window->GetBrowsingContext();
+    if (bc == bc->Top()) {
+      SetActiveBrowsingContextInContent(nullptr, aActionId);
+    }
+  }
+
+  if (mFocusedWindow) {
+    Blur(nullptr, nullptr, true, true, false, aActionId);
+  }
+
+  mWindowBeingLowered = nullptr;
+}
+
+nsresult nsFocusManager::ContentRemoved(Document* aDocument,
+                                        nsIContent* aContent) {
+  NS_ENSURE_ARG(aDocument);
+  NS_ENSURE_ARG(aContent);
+
+  nsPIDOMWindowOuter* window = aDocument->GetWindow();
+  if (!window) {
+    return NS_OK;
+  }
+
+  // if the content is currently focused in the window, or is an
+  // shadow-including inclusive ancestor of the currently focused element,
+  // reset the focus within that window.
+  Element* content = window->GetFocusedElement();
+  if (!content) {
+    return NS_OK;
+  }
+
+  if (!nsContentUtils::ContentIsHostIncludingDescendantOf(content, aContent)) {
+    return NS_OK;
+  }
+
+  Element* newFocusedElement = [&]() -> Element* {
+    if (auto* sr = ShadowRoot::FromNode(aContent)) {
+      if (sr->IsUAWidget() && sr->Host()->IsHTMLElement(nsGkAtoms::input)) {
+        return sr->Host();
+      }
+    }
+    return nullptr;
+  }();
+
+  window->SetFocusedElement(newFocusedElement);
+
+  // if this window is currently focused, clear the global focused
+  // element as well, but don't fire any events.
+  if (window->GetBrowsingContext() == GetFocusedBrowsingContext()) {
+    mFocusedElement = newFocusedElement;
+  } else if (Document* subdoc = aDocument->GetSubDocumentFor(content)) {
+    // Check if the node that was focused is an iframe or similar by looking if
+    // it has a subdocument. This would indicate that this focused iframe
+    // and its descendants will be going away. We will need to move the focus
+    // somewhere else, so just clear the focus in the toplevel window so that no
+    // element is focused.
+    //
+    // The Fission case is handled in FlushAndCheckIfFocusable().
+    if (nsCOMPtr<nsIDocShell> docShell = subdoc->GetDocShell()) {
+      nsCOMPtr<nsPIDOMWindowOuter> childWindow = docShell->GetWindow();
+      if (childWindow &&
+          IsSameOrAncestor(childWindow, GetFocusedBrowsingContext())) {
+        if (XRE_IsParentProcess()) {
+          nsCOMPtr<nsPIDOMWindowOuter> activeWindow = mActiveWindow;
+          ClearFocus(activeWindow);
+        } else {
+          BrowsingContext* active = GetActiveBrowsingContext();
+          if (active) {
+            if (active->IsInProcess()) {
+              nsCOMPtr<nsPIDOMWindowOuter> activeWindow =
+                  active->GetDOMWindow();
+              ClearFocus(activeWindow);
+            } else {
+              mozilla::dom::ContentChild* contentChild =
+                  mozilla::dom::ContentChild::GetSingleton();
+              MOZ_ASSERT(contentChild);
+              contentChild->SendClearFocus(active);
+            }
+          }  // no else, because ClearFocus does nothing with nullptr
+        }
+      }
+    }
+  }
+
+  // Notify the editor in case we removed its ancestor limiter.
+  if (content->IsEditable()) {
+    if (nsCOMPtr<nsIDocShell> docShell = aDocument->GetDocShell()) {
+      if (RefPtr<HTMLEditor> htmlEditor = docShell->GetHTMLEditor()) {
+        RefPtr<Selection> selection = htmlEditor->GetSelection();
+        if (selection && selection->GetFrameSelection() &&
+            content == selection->GetFrameSelection()->GetAncestorLimiter()) {
+          htmlEditor->FinalizeSelection();
+        }
+      }
+    }
+  }
+
+  if (!newFocusedElement) {
+    NotifyFocusStateChange(content, newFocusedElement, 0,
+                           /* aGettingFocus = */ false, false);
+  } else {
+    // We should already have the right state, which is managed by the <input>
+    // widget.
+    MOZ_ASSERT(newFocusedElement->State().HasState(ElementState::FOCUS));
+  }
+  return NS_OK;
+}
+
+void nsFocusManager::WindowShown(mozIDOMWindowProxy* aWindow,
+                                 bool aNeedsFocus) {
+  if (!aWindow) {
+    return;
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> window = nsPIDOMWindowOuter::From(aWindow);
+
+  if (MOZ_LOG_TEST(gFocusLog, LogLevel::Debug)) {
+    LOGFOCUS(("Window %p Shown [Currently: %p %p]", window.get(),
+              mActiveWindow.get(), mFocusedWindow.get()));
+    Document* doc = window->GetExtantDoc();
+    if (doc && doc->GetDocumentURI()) {
+      LOGFOCUS(("Shown Window: %s",
+                doc->GetDocumentURI()->GetSpecOrDefault().get()));
+    }
+
+    if (mFocusedWindow) {
+      doc = mFocusedWindow->GetExtantDoc();
+      if (doc && doc->GetDocumentURI()) {
+        LOGFOCUS((" Focused Window: %s",
+                  doc->GetDocumentURI()->GetSpecOrDefault().get()));
+      }
+    }
+  }
+
+  if (XRE_IsParentProcess()) {
+    if (BrowsingContext* bc = window->GetBrowsingContext()) {
+      if (bc->IsTop()) {
+        bc->SetIsActiveBrowserWindow(bc->GetIsActiveBrowserWindow());
+      }
+    }
+  }
+
+  if (XRE_IsParentProcess()) {
+    if (mFocusedWindow != window) {
+      return;
+    }
+  } else {
+    BrowsingContext* bc = window->GetBrowsingContext();
+    if (!bc || mFocusedBrowsingContextInContent != bc) {
+      return;
+    }
+    // Sync the window for a newly-created OOP iframe
+    // Set actionId to zero to signify that it should be ignored.
+    SetFocusedWindowInternal(window, 0, false);
+  }
+
+  if (aNeedsFocus) {
+    nsCOMPtr<nsPIDOMWindowOuter> currentWindow;
+    RefPtr<Element> currentFocus = GetFocusedDescendant(
+        window, eIncludeAllDescendants, getter_AddRefs(currentWindow));
+
+    if (currentWindow) {
+      Focus(currentWindow, currentFocus, 0, true, false, false, true,
+            GenerateFocusActionId());
+    }
+  } else {
+    // Sometimes, an element in a window can be focused before the window is
+    // visible, which would mean that the widget may not be properly focused.
+    // When the window becomes visible, make sure the right widget is focused.
+    EnsureCurrentWidgetFocused(CallerType::System);
+  }
+}
+
+void nsFocusManager::WindowHidden(mozIDOMWindowProxy* aWindow,
+                                  uint64_t aActionId) {
+  // if there is no window or it is not the same or an ancestor of the
+  // currently focused window, just return, as the current focus will not
+  // be affected.
+
+  if (!aWindow) {
+    return;
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> window = nsPIDOMWindowOuter::From(aWindow);
+
+  if (MOZ_LOG_TEST(gFocusLog, LogLevel::Debug)) {
+    LOGFOCUS(("Window %p Hidden [Currently: %p %p] actionid: %" PRIu64,
+              window.get(), mActiveWindow.get(), mFocusedWindow.get(),
+              aActionId));
+    nsAutoCString spec;
+    Document* doc = window->GetExtantDoc();
+    if (doc && doc->GetDocumentURI()) {
+      LOGFOCUS(("  Hide Window: %s",
+                doc->GetDocumentURI()->GetSpecOrDefault().get()));
+    }
+
+    if (mFocusedWindow) {
+      doc = mFocusedWindow->GetExtantDoc();
+      if (doc && doc->GetDocumentURI()) {
+        LOGFOCUS(("  Focused Window: %s",
+                  doc->GetDocumentURI()->GetSpecOrDefault().get()));
+      }
+    }
+
+    if (mActiveWindow) {
+      doc = mActiveWindow->GetExtantDoc();
+      if (doc && doc->GetDocumentURI()) {
+        LOGFOCUS(("  Active Window: %s",
+                  doc->GetDocumentURI()->GetSpecOrDefault().get()));
+      }
+    }
+  }
+
+  if (!IsSameOrAncestor(window, mFocusedWindow)) {
+    return;
+  }
+
+  // at this point, we know that the window being hidden is either the focused
+  // window, or an ancestor of the focused window. Either way, the focus is no
+  // longer valid, so it needs to be updated.
+
+  const RefPtr<Element> oldFocusedElement = std::move(mFocusedElement);
+
+  nsCOMPtr<nsIDocShell> focusedDocShell = mFocusedWindow->GetDocShell();
+  if (!focusedDocShell) {
+    return;
+  }
+
+  const RefPtr<PresShell> presShell = focusedDocShell->GetPresShell();
+
+  if (oldFocusedElement && oldFocusedElement->IsInComposedDoc()) {
+    NotifyFocusStateChange(oldFocusedElement, nullptr, 0, false, false);
+    window->UpdateCommands(u"focus"_ns, nullptr, 0);
+
+    if (presShell) {
+      RefPtr<Document> composedDoc = oldFocusedElement->GetComposedDoc();
+      SendFocusOrBlurEvent(eBlur, presShell, composedDoc, oldFocusedElement,
+                           false);
+    }
+  }
+
+  const RefPtr<nsPresContext> focusedPresContext =
+      presShell ? presShell->GetPresContext() : nullptr;
+  IMEStateManager::OnChangeFocus(focusedPresContext, nullptr,
+                                 GetFocusMoveActionCause(0));
+  if (presShell) {
+    SetCaretVisible(presShell, false, nullptr);
+  }
+
+  // If a window is being "hidden" because its BrowsingContext is changing
+  // remoteness, we don't want to handle docshell destruction by moving focus.
+  // Instead, the focused browsing context should stay the way it is (so that
+  // the newly "shown" window in the other process knows to take focus) and
+  // we should just null out the process-local field.
+  nsCOMPtr<nsIDocShell> docShellBeingHidden = window->GetDocShell();
+  // Check if we're currently hiding a non-remote nsDocShell due to its
+  // BrowsingContext navigating to become remote. Normally, when a focused
+  // subframe is hidden, focus is moved to the frame element, but focus should
+  // stay with the BrowsingContext when performing a process switch. We don't
+  // need to consider process switches where the hiding docshell is already
+  // remote (ie. GetEmbedderElement is nullptr), as shifting remoteness to the
+  // frame element is handled elsewhere.
+  if (docShellBeingHidden &&
+      nsDocShell::Cast(docShellBeingHidden)->WillChangeProcess() &&
+      docShellBeingHidden->GetBrowsingContext()->GetEmbedderElement()) {
+    if (mFocusedWindow != window) {
+      // The window being hidden is an ancestor of the focused window.
+#ifdef DEBUG
+      BrowsingContext* ancestor = window->GetBrowsingContext();
+      BrowsingContext* bc = mFocusedWindow->GetBrowsingContext();
+      for (;;) {
+        if (!bc) {
+          MOZ_ASSERT(false, "Should have found ancestor");
+        }
+        bc = bc->GetParent();
+        if (ancestor == bc) {
+          break;
+        }
+      }
+#endif
+      // This call adjusts the focused browsing context and window.
+      // The latter gets nulled out immediately below.
+      SetFocusedWindowInternal(window, aActionId);
+    }
+    mFocusedWindow = nullptr;
+    window->SetFocusedElement(nullptr);
+    return;
+  }
+
+  // if the docshell being hidden is being destroyed, then we want to move
+  // focus somewhere else. Call ClearFocus on the toplevel window, which
+  // will have the effect of clearing the focus and moving the focused window
+  // to the toplevel window. But if the window isn't being destroyed, we are
+  // likely just loading a new document in it, so we want to maintain the
+  // focused window so that the new document gets properly focused.
+  bool beingDestroyed = !docShellBeingHidden;
+  if (docShellBeingHidden) {
+    docShellBeingHidden->IsBeingDestroyed(&beingDestroyed);
+  }
+  if (beingDestroyed) {
+    // There is usually no need to do anything if a toplevel window is going
+    // away, as we assume that WindowLowered will be called. However, this may
+    // not happen if nsIAppStartup::eForceQuit is used to quit, and can cause
+    // a leak. So if the active window is being destroyed, call WindowLowered
+    // directly.
+
+    if (XRE_IsParentProcess()) {
+      nsCOMPtr<nsPIDOMWindowOuter> activeWindow = mActiveWindow;
+      if (activeWindow == mFocusedWindow || activeWindow == window) {
+        WindowLowered(activeWindow, aActionId);
+      } else {
+        ClearFocus(activeWindow);
+      }
+    } else {
+      BrowsingContext* active = GetActiveBrowsingContext();
+      if (active) {
+        if (nsCOMPtr<nsPIDOMWindowOuter> activeWindow =
+                active->GetDOMWindow()) {
+          if ((mFocusedWindow &&
+               mFocusedWindow->GetBrowsingContext() == active) ||
+              (window->GetBrowsingContext() == active)) {
+            WindowLowered(activeWindow, aActionId);
+          } else {
+            ClearFocus(activeWindow);
+          }
+        }  // else do nothing when an out-of-process iframe is torn down
+      }
+    }
+    return;
+  }
+
+  if (!XRE_IsParentProcess() &&
+      mActiveBrowsingContextInContent ==
+          docShellBeingHidden->GetBrowsingContext() &&
+      mActiveBrowsingContextInContent->GetIsInBFCache()) {
+    SetActiveBrowsingContextInContent(nullptr, aActionId);
+  }
+
+  // if the window being hidden is an ancestor of the focused window, adjust
+  // the focused window so that it points to the one being hidden. This
+  // ensures that the focused window isn't in a chain of frames that doesn't
+  // exist any more.
+  if (window != mFocusedWindow) {
+    nsCOMPtr<nsIDocShellTreeItem> dsti =
+        mFocusedWindow ? mFocusedWindow->GetDocShell() : nullptr;
+    if (dsti) {
+      nsCOMPtr<nsIDocShellTreeItem> parentDsti;
+      dsti->GetInProcessParent(getter_AddRefs(parentDsti));
+      if (parentDsti) {
+        if (nsCOMPtr<nsPIDOMWindowOuter> parentWindow =
+                parentDsti->GetWindow()) {
+          parentWindow->SetFocusedElement(nullptr);
+        }
+      }
+    }
+
+    SetFocusedWindowInternal(window, aActionId);
+  }
+}
+
+void nsFocusManager::FireDelayedEvents(Document* aDocument) {
+  MOZ_ASSERT(aDocument);
+
+  // fire any delayed focus and blur events in the same order that they were
+  // added
+  for (uint32_t i = 0; i < mDelayedBlurFocusEvents.Length(); i++) {
+    if (mDelayedBlurFocusEvents[i].mDocument == aDocument) {
+      if (!aDocument->GetInnerWindow() ||
+          !aDocument->GetInnerWindow()->IsCurrentInnerWindow()) {
+        // If the document was navigated away from or is defunct, don't bother
+        // firing events on it. Note the symmetry between this condition and
+        // the similar one in Document.cpp:FireOrClearDelayedEvents.
+        mDelayedBlurFocusEvents.RemoveElementAt(i);
+        --i;
+      } else if (!aDocument->EventHandlingSuppressed()) {
+        EventMessage message = mDelayedBlurFocusEvents[i].mEventMessage;
+        nsCOMPtr<EventTarget> target = mDelayedBlurFocusEvents[i].mTarget;
+        RefPtr<PresShell> presShell = mDelayedBlurFocusEvents[i].mPresShell;
+        nsCOMPtr<EventTarget> relatedTarget =
+            mDelayedBlurFocusEvents[i].mRelatedTarget;
+        mDelayedBlurFocusEvents.RemoveElementAt(i);
+
+        FireFocusOrBlurEvent(message, presShell, target, false, false,
+                             relatedTarget);
+        --i;
+      }
+    }
+  }
+}
+
+void nsFocusManager::WasNuked(nsPIDOMWindowOuter* aWindow) {
+  MOZ_ASSERT(aWindow, "Expected non-null window.");
+  MOZ_ASSERT(aWindow != mActiveWindow,
+             "How come we're nuking a window that's still active?");
+  if (aWindow == mFocusedWindow) {
+    mFocusedWindow = nullptr;
+    SetFocusedBrowsingContext(nullptr, GenerateFocusActionId());
+    mFocusedElement = nullptr;
+  }
+}
+
+nsFocusManager::BlurredElementInfo::BlurredElementInfo(Element& aElement)
+    : mElement(aElement) {}
+
+nsFocusManager::BlurredElementInfo::~BlurredElementInfo() = default;
+
+// https://drafts.csswg.org/selectors-4/#the-focus-visible-pseudo
+static bool ShouldMatchFocusVisible(nsPIDOMWindowOuter* aWindow,
+                                    const Element& aElement,
+                                    int32_t aFocusFlags) {
+  // If we were explicitly requested to show the ring, do it.
+  if (aFocusFlags & nsIFocusManager::FLAG_SHOWRING) {
+    return true;
+  }
+
+  if (aFocusFlags & nsIFocusManager::FLAG_NOSHOWRING) {
+    return false;
+  }
+
+  if (aWindow->ShouldShowFocusRing()) {
+    // The window decision also trumps any other heuristic.
+    return true;
+  }
+
+  // Any element which supports keyboard input (such as an input element, or any
+  // other element which may trigger a virtual keyboard to be shown on focus if
+  // a physical keyboard is not present) should always match :focus-visible when
+  // focused.
+  {
+    if (aElement.IsHTMLElement(nsGkAtoms::textarea) || aElement.IsEditable()) {
+      return true;
+    }
+
+    if (auto* input = HTMLInputElement::FromNode(aElement)) {
+      if (input->IsSingleLineTextControl()) {
+        return true;
+      }
+    }
+  }
+
+  switch (nsFocusManager::GetFocusMoveActionCause(aFocusFlags)) {
+    case InputContextAction::CAUSE_KEY:
+      // If the user interacts with the page via the keyboard, the currently
+      // focused element should match :focus-visible (i.e. keyboard usage may
+      // change whether this pseudo-class matches even if it doesn't affect
+      // :focus).
+      return true;
+    case InputContextAction::CAUSE_UNKNOWN:
+      // We render outlines if the last "known" focus method was by key or there
+      // was no previous known focus method, otherwise we don't.
+      return aWindow->UnknownFocusMethodShouldShowOutline();
+    case InputContextAction::CAUSE_MOUSE:
+    case InputContextAction::CAUSE_TOUCH:
+    case InputContextAction::CAUSE_LONGPRESS:
+      // If the user interacts with the page via a pointing device, such that
+      // the focus is moved to a new element which does not support user input,
+      // the newly focused element should not match :focus-visible.
+      return false;
+    case InputContextAction::CAUSE_UNKNOWN_CHROME:
+    case InputContextAction::CAUSE_UNKNOWN_DURING_KEYBOARD_INPUT:
+    case InputContextAction::CAUSE_UNKNOWN_DURING_NON_KEYBOARD_INPUT:
+      // TODO(emilio): We could return some of these though, looking at
+      // UserActivation. We may want to suppress focus rings for unknown /
+      // programatic focus if the user is interacting with the page but not
+      // during keyboard input, or such.
+      MOZ_ASSERT_UNREACHABLE(
+          "These don't get returned by GetFocusMoveActionCause");
+      break;
+  }
+  return false;
+}
+
+/* static */
+void nsFocusManager::NotifyFocusStateChange(Element* aElement,
+                                            Element* aElementToFocus,
+                                            int32_t aFlags, bool aGettingFocus,
+                                            bool aShouldShowFocusRing) {
+  MOZ_ASSERT_IF(aElementToFocus, !aGettingFocus);
+  nsIContent* commonAncestor = nullptr;
+  if (aElementToFocus) {
+    commonAncestor = nsContentUtils::GetCommonFlattenedTreeAncestor(
+        aElement, aElementToFocus);
+  }
+
+  if (aGettingFocus) {
+    ElementState stateToAdd = ElementState::FOCUS;
+    if (aShouldShowFocusRing) {
+      stateToAdd |= ElementState::FOCUSRING;
+    }
+    aElement->AddStates(stateToAdd);
+
+    for (nsIContent* host = aElement->GetContainingShadowHost(); host;
+         host = host->GetContainingShadowHost()) {
+      host->AsElement()->AddStates(ElementState::FOCUS);
+    }
+  } else {
+    constexpr auto kStatesToRemove =
+        ElementState::FOCUS | ElementState::FOCUSRING;
+    aElement->RemoveStates(kStatesToRemove);
+    for (nsIContent* host = aElement->GetContainingShadowHost(); host;
+         host = host->GetContainingShadowHost()) {
+      host->AsElement()->RemoveStates(kStatesToRemove);
+    }
+  }
+
+  // Special case for <input type="checkbox"> and <input type="radio">.
+  // The other browsers cancel active state when they gets lost focus, but
+  // does not do it for the other elements such as <button> and <a href="...">.
+  // Additionally, they may be activated with <label>, but they will get focus
+  // at `click`, but activated at `mousedown`.  Therefore, we need to cancel
+  // active state at moving focus.
+  if (RefPtr<nsPresContext> presContext =
+          aElement->GetPresContext(Element::PresContextFor::eForComposedDoc)) {
+    RefPtr<EventStateManager> esm = presContext->EventStateManager();
+    auto* activeInputElement =
+        HTMLInputElement::FromNodeOrNull(esm->GetActiveContent());
+    if (activeInputElement &&
+        (activeInputElement->ControlType() == FormControlType::InputCheckbox ||
+         activeInputElement->ControlType() == FormControlType::InputRadio) &&
+        !activeInputElement->State().HasState(ElementState::FOCUS)) {
+      esm->SetContentState(nullptr, ElementState::ACTIVE);
+    }
+  }
+
+  for (nsIContent* content = aElement; content && content != commonAncestor;
+       content = content->GetFlattenedTreeParent()) {
+    Element* element = Element::FromNode(content);
+    if (!element) {
+      continue;
+    }
+
+    if (aGettingFocus) {
+      if (element->State().HasState(ElementState::FOCUS_WITHIN)) {
+        break;
+      }
+      element->AddStates(ElementState::FOCUS_WITHIN);
+    } else {
+      element->RemoveStates(ElementState::FOCUS_WITHIN);
+    }
+  }
+}
+
+// static
+void nsFocusManager::EnsureCurrentWidgetFocused(CallerType aCallerType) {
+  if (!mFocusedWindow || sTestMode) return;
+
+  // get the main child widget for the focused window and ensure that the
+  // platform knows that this widget is focused.
+  nsCOMPtr<nsIDocShell> docShell = mFocusedWindow->GetDocShell();
+  if (!docShell) {
+    return;
+  }
+  RefPtr<PresShell> presShell = docShell->GetPresShell();
+  if (!presShell) {
+    return;
+  }
+  nsViewManager* vm = presShell->GetViewManager();
+  if (!vm) {
+    return;
+  }
+  nsCOMPtr<nsIWidget> widget = vm->GetRootWidget();
+  if (!widget) {
+    return;
+  }
+  widget->SetFocus(nsIWidget::Raise::No, aCallerType);
+}
+
+void nsFocusManager::ActivateOrDeactivate(nsPIDOMWindowOuter* aWindow,
+                                          bool aActive) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  if (!aWindow) {
+    return;
+  }
+
+  if (BrowsingContext* bc = aWindow->GetBrowsingContext()) {
+    MOZ_ASSERT(bc->IsTop());
+
+    RefPtr<CanonicalBrowsingContext> chromeTop =
+        bc->Canonical()->TopCrossChromeBoundary();
+    MOZ_ASSERT(bc == chromeTop);
+
+    chromeTop->SetIsActiveBrowserWindow(aActive);
+    chromeTop->CallOnAllTopDescendants(
+        [aActive](CanonicalBrowsingContext* aBrowsingContext) -> CallState {
+          aBrowsingContext->SetIsActiveBrowserWindow(aActive);
+          return CallState::Continue;
+        });
+  }
+
+  if (aWindow->GetExtantDoc()) {
+    nsContentUtils::DispatchEventOnlyToChrome(
+        aWindow->GetExtantDoc(), aWindow->GetCurrentInnerWindow(),
+        aActive ? u"activate"_ns : u"deactivate"_ns, CanBubble::eYes,
+        Cancelable::eYes, nullptr);
+  }
+}
+
+// Retrieves innerWindowId of the window of the last focused element to
+// log a warning to the website console.
+void LogWarningFullscreenWindowRaise(Element* aElement) {
+  nsCOMPtr<nsFrameLoaderOwner> frameLoaderOwner(do_QueryInterface(aElement));
+  NS_ENSURE_TRUE_VOID(frameLoaderOwner);
+
+  RefPtr<nsFrameLoader> frameLoader = frameLoaderOwner->GetFrameLoader();
+  NS_ENSURE_TRUE_VOID(frameLoaderOwner);
+
+  RefPtr<BrowsingContext> browsingContext = frameLoader->GetBrowsingContext();
+  NS_ENSURE_TRUE_VOID(browsingContext);
+
+  WindowGlobalParent* windowGlobalParent =
+      browsingContext->Canonical()->GetCurrentWindowGlobal();
+  NS_ENSURE_TRUE_VOID(windowGlobalParent);
+
+  // Log to console
+  nsAutoString localizedMsg;
+  nsTArray<nsString> params;
+  nsresult rv = nsContentUtils::FormatLocalizedString(
+      nsContentUtils::eDOM_PROPERTIES, "FullscreenExitWindowFocus", params,
+      localizedMsg);
+
+  NS_ENSURE_SUCCESS_VOID(rv);
+
+  Unused << nsContentUtils::ReportToConsoleByWindowID(
+      localizedMsg, nsIScriptError::warningFlag, "DOM"_ns,
+      windowGlobalParent->InnerWindowId(),
+      windowGlobalParent->GetDocumentURI());
+}
+
+// Ensure that when an embedded popup with a noautofocus attribute
+// like a date picker is opened and focused, the parent page does not blur
+static bool IsEmeddededInNoautofocusPopup(BrowsingContext& aBc) {
+  auto* embedder = aBc.GetEmbedderElement();
+  if (!embedder) {
+    return false;
+  }
+  nsIFrame* f = embedder->GetPrimaryFrame();
+  if (!f || !f->HasAnyStateBits(NS_FRAME_IN_POPUP)) {
+    return false;
+  }
+
+  nsIFrame* menuPopup =
+      nsLayoutUtils::GetClosestFrameOfType(f, LayoutFrameType::MenuPopup);
+  MOZ_ASSERT(menuPopup, "NS_FRAME_IN_POPUP lied?");
+  return static_cast<nsMenuPopupFrame*>(menuPopup)
+      ->PopupElement()
+      .GetXULBoolAttr(nsGkAtoms::noautofocus);
+}
+
+Maybe<uint64_t> nsFocusManager::SetFocusInner(Element* aNewContent,
+                                              int32_t aFlags,
+                                              bool aFocusChanged,
+                                              bool aAdjustWidget) {
+  // if the element is not focusable, just return and leave the focus as is
+  RefPtr<Element> elementToFocus =
+      FlushAndCheckIfFocusable(aNewContent, aFlags);
+  if (!elementToFocus) {
+    return Nothing();
+  }
+
+  const RefPtr<BrowsingContext> focusedBrowsingContext =
+      GetFocusedBrowsingContext();
+
+  // check if the element to focus is a frame (iframe) containing a child
+  // document. Frames are never directly focused; instead focusing a frame
+  // means focus what is inside the frame. To do this, the descendant content
+  // within the frame is retrieved and that will be focused instead.
+  nsCOMPtr<nsPIDOMWindowOuter> newWindow;
+  nsCOMPtr<nsPIDOMWindowOuter> subWindow = GetContentWindow(elementToFocus);
+  if (subWindow) {
+    elementToFocus = GetFocusedDescendant(subWindow, eIncludeAllDescendants,
+                                          getter_AddRefs(newWindow));
+
+    // since a window is being refocused, clear aFocusChanged so that the
+    // caret position isn't updated.
+    aFocusChanged = false;
+  }
+
+  // unless it was set above, retrieve the window for the element to focus
+  if (!newWindow) {
+    newWindow = GetCurrentWindow(elementToFocus);
+  }
+
+  RefPtr<BrowsingContext> newBrowsingContext;
+  if (newWindow) {
+    newBrowsingContext = newWindow->GetBrowsingContext();
+  }
+
+  // if the element is already focused, just return. Note that this happens
+  // after the frame check above so that we compare the element that will be
+  // focused rather than the frame it is in.
+  if (!newWindow || (newBrowsingContext == GetFocusedBrowsingContext() &&
+                     elementToFocus == mFocusedElement)) {
+    return Nothing();
+  }
+
+  MOZ_ASSERT(newBrowsingContext);
+
+  BrowsingContext* browsingContextToFocus = newBrowsingContext;
+  if (RefPtr<nsFrameLoaderOwner> flo = do_QueryObject(elementToFocus)) {
+    // Only look at pre-existing browsing contexts. If this function is
+    // called during reflow, calling GetBrowsingContext() could cause frame
+    // loader initialization at a time when it isn't safe.
+    if (BrowsingContext* bc = flo->GetExtantBrowsingContext()) {
+      // If focus is already in the subtree rooted at bc, return early
+      // to match the single-process focus semantics. Otherwise, we'd
+      // blur and immediately refocus whatever is focused.
+      BrowsingContext* walk = focusedBrowsingContext;
+      while (walk) {
+        if (walk == bc) {
+          return Nothing();
+        }
+        walk = walk->GetParent();
+      }
+      browsingContextToFocus = bc;
+    }
+  }
+
+  // don't allow focus to be placed in docshells or descendants of docshells
+  // that are being destroyed. Also, ensure that the page hasn't been
+  // unloaded. The prevents content from being refocused during an unload event.
+  nsCOMPtr<nsIDocShell> newDocShell = newWindow->GetDocShell();
+  nsCOMPtr<nsIDocShell> docShell = newDocShell;
+  while (docShell) {
+    bool inUnload;
+    docShell->GetIsInUnload(&inUnload);
+    if (inUnload) {
+      return Nothing();
+    }
+
+    bool beingDestroyed;
+    docShell->IsBeingDestroyed(&beingDestroyed);
+    if (beingDestroyed) {
+      return Nothing();
+    }
+
+    BrowsingContext* bc = docShell->GetBrowsingContext();
+
+    nsCOMPtr<nsIDocShellTreeItem> parentDsti;
+    docShell->GetInProcessParent(getter_AddRefs(parentDsti));
+    docShell = do_QueryInterface(parentDsti);
+    if (!docShell && !XRE_IsParentProcess()) {
+      // We don't have an in-process parent, but let's see if we have
+      // an in-process ancestor or if an out-of-process ancestor
+      // is discarded.
+      do {
+        bc = bc->GetParent();
+        if (bc && bc->IsDiscarded()) {
+          return Nothing();
+        }
+      } while (bc && !bc->IsInProcess());
+      if (bc) {
+        docShell = bc->GetDocShell();
+      } else {
+        docShell = nullptr;
+      }
+    }
+  }
+
+  bool focusMovesToDifferentBC =
+      (focusedBrowsingContext != browsingContextToFocus);
+
+  if (focusedBrowsingContext && focusMovesToDifferentBC &&
+      nsContentUtils::IsHandlingKeyBoardEvent() &&
+      !nsContentUtils::LegacyIsCallerChromeOrNativeCode()) {
+    MOZ_ASSERT(browsingContextToFocus,
+               "BrowsingContext to focus should be non-null.");
+
+    nsIPrincipal* focusedPrincipal = nullptr;
+    nsIPrincipal* newPrincipal = nullptr;
+
+    if (XRE_IsParentProcess()) {
+      if (WindowGlobalParent* focusedWindowGlobalParent =
+              focusedBrowsingContext->Canonical()->GetCurrentWindowGlobal()) {
+        focusedPrincipal = focusedWindowGlobalParent->DocumentPrincipal();
+      }
+
+      if (WindowGlobalParent* newWindowGlobalParent =
+              browsingContextToFocus->Canonical()->GetCurrentWindowGlobal()) {
+        newPrincipal = newWindowGlobalParent->DocumentPrincipal();
+      }
+    } else if (focusedBrowsingContext->IsInProcess() &&
+               browsingContextToFocus->IsInProcess()) {
+      nsCOMPtr<nsIScriptObjectPrincipal> focused =
+          do_QueryInterface(focusedBrowsingContext->GetDOMWindow());
+      nsCOMPtr<nsIScriptObjectPrincipal> newFocus =
+          do_QueryInterface(browsingContextToFocus->GetDOMWindow());
+      MOZ_ASSERT(focused && newFocus,
+                 "BrowsingContext should always have a window here.");
+      focusedPrincipal = focused->GetPrincipal();
+      newPrincipal = newFocus->GetPrincipal();
+    }
+
+    if (!focusedPrincipal || !newPrincipal) {
+      return Nothing();
+    }
+
+    if (!focusedPrincipal->Subsumes(newPrincipal)) {
+      NS_WARNING("Not allowed to focus the new window!");
+      return Nothing();
+    }
+  }
+
+  // to check if the new element is in the active window, compare the
+  // new root docshell for the new element with the active window's docshell.
+  RefPtr<BrowsingContext> newRootBrowsingContext = nullptr;
+  bool isElementInActiveWindow = false;
+  if (XRE_IsParentProcess()) {
+    nsCOMPtr<nsPIDOMWindowOuter> newRootWindow = nullptr;
+    nsCOMPtr<nsIDocShellTreeItem> dsti = newWindow->GetDocShell();
+    if (dsti) {
+      nsCOMPtr<nsIDocShellTreeItem> root;
+      dsti->GetInProcessRootTreeItem(getter_AddRefs(root));
+      newRootWindow = root ? root->GetWindow() : nullptr;
+
+      isElementInActiveWindow =
+          (mActiveWindow && newRootWindow == mActiveWindow);
+    }
+    if (newRootWindow) {
+      newRootBrowsingContext = newRootWindow->GetBrowsingContext();
+    }
+  } else {
+    // XXX This is wrong for `<iframe mozbrowser>` and for XUL
+    // `<browser remote="true">`. See:
+    // https://searchfox.org/mozilla-central/rev/8a63fc190b39ed6951abb4aef4a56487a43962bc/dom/base/nsFrameLoader.cpp#229-232
+    newRootBrowsingContext = newBrowsingContext->Top();
+    // to check if the new element is in the active window, compare the
+    // new root docshell for the new element with the active window's docshell.
+    isElementInActiveWindow =
+        (GetActiveBrowsingContext() == newRootBrowsingContext);
+  }
+
+  // Exit fullscreen if a website focuses another window
+  if (StaticPrefs::full_screen_api_exit_on_windowRaise() &&
+      !isElementInActiveWindow && (aFlags & FLAG_RAISE)) {
+    if (XRE_IsParentProcess()) {
+      if (Document* doc = mActiveWindow ? mActiveWindow->GetDoc() : nullptr) {
+        Document::ClearPendingFullscreenRequests(doc);
+        if (doc->GetFullscreenElement()) {
+          LogWarningFullscreenWindowRaise(mFocusedElement);
+          Document::AsyncExitFullscreen(doc);
+        }
+      }
+    } else {
+      BrowsingContext* activeBrowsingContext = GetActiveBrowsingContext();
+      if (activeBrowsingContext) {
+        nsIDocShell* shell = activeBrowsingContext->GetDocShell();
+        if (shell) {
+          if (Document* doc = shell->GetDocument()) {
+            Document::ClearPendingFullscreenRequests(doc);
+            if (doc->GetFullscreenElement()) {
+              Document::AsyncExitFullscreen(doc);
+            }
+          }
+        } else {
+          mozilla::dom::ContentChild* contentChild =
+              mozilla::dom::ContentChild::GetSingleton();
+          MOZ_ASSERT(contentChild);
+          contentChild->SendMaybeExitFullscreen(activeBrowsingContext);
+        }
+      }
+    }
+  }
+
+  // Exit fullscreen if we're focusing a windowed plugin on a non-MacOSX
+  // system. We don't control event dispatch to windowed plugins on non-MacOSX,
+  // so we can't display the "Press ESC to leave fullscreen mode" warning on
+  // key input if a windowed plugin is focused, so just exit fullscreen
+  // to guard against phishing.
+#ifndef XP_MACOSX
+  if (elementToFocus &&
+      nsContentUtils::GetInProcessSubtreeRootDocument(
+          elementToFocus->OwnerDoc())
+          ->GetFullscreenElement() &&
+      nsContentUtils::HasPluginWithUncontrolledEventDispatch(elementToFocus)) {
+    nsContentUtils::ReportToConsole(nsIScriptError::warningFlag, "DOM"_ns,
+                                    elementToFocus->OwnerDoc(),
+                                    nsContentUtils::eDOM_PROPERTIES,
+                                    "FocusedWindowedPluginWhileFullscreen");
+    Document::AsyncExitFullscreen(elementToFocus->OwnerDoc());
+  }
+#endif
+
+  // if the FLAG_NOSWITCHFRAME flag is used, only allow the focus to be
+  // shifted away from the current element if the new shell to focus is
+  // the same or an ancestor shell of the currently focused shell.
+  bool allowFrameSwitch = !(aFlags & FLAG_NOSWITCHFRAME) ||
+                          IsSameOrAncestor(newWindow, focusedBrowsingContext);
+
+  // if the element is in the active window, frame switching is allowed and
+  // the content is in a visible window, fire blur and focus events.
+  bool sendFocusEvent =
+      isElementInActiveWindow && allowFrameSwitch && IsWindowVisible(newWindow);
+
+  // Don't allow to steal the focus from chrome nodes if the caller cannot
+  // access them.
+  if (sendFocusEvent && mFocusedElement &&
+      mFocusedElement->OwnerDoc() != aNewContent->OwnerDoc() &&
+      mFocusedElement->NodePrincipal()->IsSystemPrincipal() &&
+      !nsContentUtils::LegacyIsCallerNativeCode() &&
+      !nsContentUtils::CanCallerAccess(mFocusedElement)) {
+    sendFocusEvent = false;
+  }
+
+  LOGCONTENT("Shift Focus: %s", elementToFocus.get());
+  LOGFOCUS((" Flags: %x Current Window: %p New Window: %p Current Element: %p",
+            aFlags, mFocusedWindow.get(), newWindow.get(),
+            mFocusedElement.get()));
+  const uint64_t actionId = GenerateFocusActionId();
+  LOGFOCUS(
+      (" In Active Window: %d Moves to different BrowsingContext: %d "
+       "SendFocus: %d actionid: %" PRIu64,
+       isElementInActiveWindow, focusMovesToDifferentBC, sendFocusEvent,
+       actionId));
+
+  if (sendFocusEvent) {
+    Maybe<BlurredElementInfo> blurredInfo;
+    if (mFocusedElement) {
+      blurredInfo.emplace(*mFocusedElement);
+    }
+    // return if blurring fails or the focus changes during the blur
+    if (focusedBrowsingContext) {
+      // find the common ancestor of the currently focused window and the new
+      // window. The ancestor will need to have its currently focused node
+      // cleared once the document has been blurred. Otherwise, we'll be in a
+      // state where a document is blurred yet the chain of windows above it
+      // still points to that document.
+      // For instance, in the following frame tree:
+      //   A
+      //  B C
+      //  D
+      // D is focused and we want to focus C. Once D has been blurred, we need
+      // to clear out the focus in A, otherwise A would still maintain that B
+      // was focused, and B that D was focused.
+      RefPtr<BrowsingContext> commonAncestor =
+          focusMovesToDifferentBC
+              ? GetCommonAncestor(newWindow, focusedBrowsingContext)
+              : nullptr;
+
+      const bool needToClearFocusedElement = [&] {
+        if (focusedBrowsingContext->IsChrome()) {
+          // Always reset focused element if focus is currently in chrome
+          // window, unless we're moving focus to a popup.
+          return !IsEmeddededInNoautofocusPopup(*browsingContextToFocus);
+        }
+        if (focusedBrowsingContext->Top() != browsingContextToFocus->Top()) {
+          // Only reset focused element if focus moves within the same top-level
+          // content window.
+          return false;
+        }
+        // XXX for the case that we try to focus an
+        // already-focused-remote-frame, we would still send blur and focus
+        // IPC to it, but they will not generate blur or focus event, we don't
+        // want to reset activeElement on the remote frame.
+        return focusMovesToDifferentBC || focusedBrowsingContext->IsInProcess();
+      }();
+
+      const bool remainActive =
+          focusMovesToDifferentBC &&
+          IsEmeddededInNoautofocusPopup(*browsingContextToFocus);
+
+      // TODO: MOZ_KnownLive is required due to bug 1770680
+      if (!Blur(MOZ_KnownLive(needToClearFocusedElement
+                                  ? focusedBrowsingContext.get()
+                                  : nullptr),
+                commonAncestor, focusMovesToDifferentBC, aAdjustWidget,
+                remainActive, actionId, elementToFocus)) {
+        return Some(actionId);
+      }
+    }
+
+    Focus(newWindow, elementToFocus, aFlags, focusMovesToDifferentBC,
+          aFocusChanged, false, aAdjustWidget, actionId, blurredInfo);
+  } else {
+    // otherwise, for inactive windows and when the caller cannot steal the
+    // focus, update the node in the window, and  raise the window if desired.
+    if (allowFrameSwitch) {
+      AdjustWindowFocus(newBrowsingContext, true, IsWindowVisible(newWindow),
+                        actionId);
+    }
+
+    // set the focus node and method as needed
+    uint32_t focusMethod =
+        aFocusChanged ? aFlags & METHODANDRING_MASK
+                      : newWindow->GetFocusMethod() |
+                            (aFlags & (FLAG_SHOWRING | FLAG_NOSHOWRING));
+    newWindow->SetFocusedElement(elementToFocus, focusMethod);
+    if (aFocusChanged) {
+      if (nsCOMPtr<nsIDocShell> docShell = newWindow->GetDocShell()) {
+        RefPtr<PresShell> presShell = docShell->GetPresShell();
+        if (presShell && presShell->DidInitialize()) {
+          ScrollIntoView(presShell, elementToFocus, aFlags);
+        }
+      }
+    }
+
+    // update the commands even when inactive so that the attributes for that
+    // window are up to date.
+    if (allowFrameSwitch) {
+      newWindow->UpdateCommands(u"focus"_ns, nullptr, 0);
+    }
+
+    if (aFlags & FLAG_RAISE) {
+      if (newRootBrowsingContext) {
+        if (XRE_IsParentProcess() || newRootBrowsingContext->IsInProcess()) {
+          nsCOMPtr<nsPIDOMWindowOuter> outerWindow =
+              newRootBrowsingContext->GetDOMWindow();
+          RaiseWindow(outerWindow,
+                      aFlags & FLAG_NONSYSTEMCALLER ? CallerType::NonSystem
+                                                    : CallerType::System,
+                      actionId);
+        } else {
+          mozilla::dom::ContentChild* contentChild =
+              mozilla::dom::ContentChild::GetSingleton();
+          MOZ_ASSERT(contentChild);
+          contentChild->SendRaiseWindow(newRootBrowsingContext,
+                                        aFlags & FLAG_NONSYSTEMCALLER
+                                            ? CallerType::NonSystem
+                                            : CallerType::System,
+                                        actionId);
+        }
+      }
+    }
+  }
+  return Some(actionId);
+}
+
+static already_AddRefed<BrowsingContext> GetParentIgnoreChromeBoundary(
+    BrowsingContext* aBC) {
+  // Chrome BrowsingContexts are only available in the parent process, so if
+  // we're in a content process, we only worry about the context tree.
+  if (XRE_IsParentProcess()) {
+    return aBC->Canonical()->GetParentCrossChromeBoundary();
+  }
+  return do_AddRef(aBC->GetParent());
+}
+
+bool nsFocusManager::IsSameOrAncestor(BrowsingContext* aPossibleAncestor,
+                                      BrowsingContext* aContext) const {
+  if (!aPossibleAncestor) {
+    return false;
+  }
+
+  for (RefPtr<BrowsingContext> bc = aContext; bc;
+       bc = GetParentIgnoreChromeBoundary(bc)) {
+    if (bc == aPossibleAncestor) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool nsFocusManager::IsSameOrAncestor(nsPIDOMWindowOuter* aPossibleAncestor,
+                                      nsPIDOMWindowOuter* aWindow) const {
+  if (aWindow && aPossibleAncestor) {
+    return IsSameOrAncestor(aPossibleAncestor->GetBrowsingContext(),
+                            aWindow->GetBrowsingContext());
+  }
+  return false;
+}
+
+bool nsFocusManager::IsSameOrAncestor(nsPIDOMWindowOuter* aPossibleAncestor,
+                                      BrowsingContext* aContext) const {
+  if (aPossibleAncestor) {
+    return IsSameOrAncestor(aPossibleAncestor->GetBrowsingContext(), aContext);
+  }
+  return false;
+}
+
+bool nsFocusManager::IsSameOrAncestor(BrowsingContext* aPossibleAncestor,
+                                      nsPIDOMWindowOuter* aWindow) const {
+  if (aWindow) {
+    return IsSameOrAncestor(aPossibleAncestor, aWindow->GetBrowsingContext());
+  }
+  return false;
+}
+
+mozilla::dom::BrowsingContext* nsFocusManager::GetCommonAncestor(
+    nsPIDOMWindowOuter* aWindow, mozilla::dom::BrowsingContext* aContext) {
+  NS_ENSURE_TRUE(aWindow && aContext, nullptr);
+
+  if (XRE_IsParentProcess()) {
+    nsCOMPtr<nsIDocShellTreeItem> dsti1 = aWindow->GetDocShell();
+    NS_ENSURE_TRUE(dsti1, nullptr);
+
+    nsCOMPtr<nsIDocShellTreeItem> dsti2 = aContext->GetDocShell();
+    NS_ENSURE_TRUE(dsti2, nullptr);
+
+    AutoTArray<nsIDocShellTreeItem*, 30> parents1, parents2;
+    do {
+      parents1.AppendElement(dsti1);
+      nsCOMPtr<nsIDocShellTreeItem> parentDsti1;
+      dsti1->GetInProcessParent(getter_AddRefs(parentDsti1));
+      dsti1.swap(parentDsti1);
+    } while (dsti1);
+    do {
+      parents2.AppendElement(dsti2);
+      nsCOMPtr<nsIDocShellTreeItem> parentDsti2;
+      dsti2->GetInProcessParent(getter_AddRefs(parentDsti2));
+      dsti2.swap(parentDsti2);
+    } while (dsti2);
+
+    uint32_t pos1 = parents1.Length();
+    uint32_t pos2 = parents2.Length();
+    nsIDocShellTreeItem* parent = nullptr;
+    uint32_t len;
+    for (len = std::min(pos1, pos2); len > 0; --len) {
+      nsIDocShellTreeItem* child1 = parents1.ElementAt(--pos1);
+      nsIDocShellTreeItem* child2 = parents2.ElementAt(--pos2);
+      if (child1 != child2) {
+        break;
+      }
+      parent = child1;
+    }
+
+    return parent ? parent->GetBrowsingContext() : nullptr;
+  }
+
+  BrowsingContext* bc1 = aWindow->GetBrowsingContext();
+  NS_ENSURE_TRUE(bc1, nullptr);
+
+  BrowsingContext* bc2 = aContext;
+
+  AutoTArray<BrowsingContext*, 30> parents1, parents2;
+  do {
+    parents1.AppendElement(bc1);
+    bc1 = bc1->GetParent();
+  } while (bc1);
+  do {
+    parents2.AppendElement(bc2);
+    bc2 = bc2->GetParent();
+  } while (bc2);
+
+  uint32_t pos1 = parents1.Length();
+  uint32_t pos2 = parents2.Length();
+  BrowsingContext* parent = nullptr;
+  uint32_t len;
+  for (len = std::min(pos1, pos2); len > 0; --len) {
+    BrowsingContext* child1 = parents1.ElementAt(--pos1);
+    BrowsingContext* child2 = parents2.ElementAt(--pos2);
+    if (child1 != child2) {
+      break;
+    }
+    parent = child1;
+  }
+
+  return parent;
+}
+
+bool nsFocusManager::AdjustInProcessWindowFocus(
+    BrowsingContext* aBrowsingContext, bool aCheckPermission, bool aIsVisible,
+    uint64_t aActionId) {
+  if (ActionIdComparableAndLower(aActionId,
+                                 mActionIdForFocusedBrowsingContextInContent)) {
+    LOGFOCUS(
+        ("Ignored an attempt to adjust an in-process BrowsingContext [%p] as "
+         "focused from another process due to stale action id %" PRIu64 ".",
+         aBrowsingContext, aActionId));
+    return false;
+  }
+
+  BrowsingContext* bc = aBrowsingContext;
+  bool needToNotifyOtherProcess = false;
+  while (bc) {
+    // get the containing <iframe> or equivalent element so that it can be
+    // focused below.
+    nsCOMPtr<Element> frameElement = bc->GetEmbedderElement();
+    BrowsingContext* parent = bc->GetParent();
+    if (!parent && XRE_IsParentProcess()) {
+      CanonicalBrowsingContext* canonical = bc->Canonical();
+      RefPtr<WindowGlobalParent> embedder =
+          canonical->GetEmbedderWindowGlobal();
+      if (embedder) {
+        parent = embedder->BrowsingContext();
+      }
+    }
+    bc = parent;
+    if (!bc) {
+      break;
+    }
+    if (!frameElement && XRE_IsContentProcess()) {
+      needToNotifyOtherProcess = true;
+      continue;
+    }
+
+    nsCOMPtr<nsPIDOMWindowOuter> window = bc->GetDOMWindow();
+    MOZ_ASSERT(window);
+    // if the parent window is visible but the original window was not, then we
+    // have likely moved up and out from a hidden tab to the browser window, or
+    // a similar such arrangement. Stop adjusting the current nodes.
+    if (IsWindowVisible(window) != aIsVisible) {
+      break;
+    }
+
+    // When aCheckPermission is true, we should check whether the caller can
+    // access the window or not.  If it cannot access, we should stop the
+    // adjusting.
+    if (aCheckPermission && !nsContentUtils::LegacyIsCallerNativeCode() &&
+        !nsContentUtils::CanCallerAccess(window->GetCurrentInnerWindow())) {
+      break;
+    }
+
+    if (frameElement != window->GetFocusedElement()) {
+      window->SetFocusedElement(frameElement);
+
+      RefPtr<nsFrameLoaderOwner> loaderOwner = do_QueryObject(frameElement);
+      MOZ_ASSERT(loaderOwner);
+      RefPtr<nsFrameLoader> loader = loaderOwner->GetFrameLoader();
+      if (loader && loader->IsRemoteFrame() &&
+          GetFocusedBrowsingContext() == bc) {
+        Blur(nullptr, nullptr, true, true, false, aActionId);
+      }
+    }
+  }
+  return needToNotifyOtherProcess;
+}
+
+void nsFocusManager::AdjustWindowFocus(BrowsingContext* aBrowsingContext,
+                                       bool aCheckPermission, bool aIsVisible,
+                                       uint64_t aActionId) {
+  if (AdjustInProcessWindowFocus(aBrowsingContext, aCheckPermission, aIsVisible,
+                                 aActionId)) {
+    // Some ancestors of aBrowsingContext isn't in this process, so notify other
+    // processes to adjust their focused element.
+    mozilla::dom::ContentChild* contentChild =
+        mozilla::dom::ContentChild::GetSingleton();
+    MOZ_ASSERT(contentChild);
+    contentChild->SendAdjustWindowFocus(aBrowsingContext, aIsVisible,
+                                        aActionId);
+  }
+}
+
+bool nsFocusManager::IsWindowVisible(nsPIDOMWindowOuter* aWindow) {
+  if (!aWindow || aWindow->IsFrozen()) {
+    return false;
+  }
+
+  // Check if the inner window is frozen as well. This can happen when a focus
+  // change occurs while restoring a previous page.
+  nsPIDOMWindowInner* innerWindow = aWindow->GetCurrentInnerWindow();
+  if (!innerWindow || innerWindow->IsFrozen()) {
+    return false;
+  }
+
+  nsCOMPtr<nsIDocShell> docShell = aWindow->GetDocShell();
+  nsCOMPtr<nsIBaseWindow> baseWin(do_QueryInterface(docShell));
+  if (!baseWin) {
+    return false;
+  }
+
+  bool visible = false;
+  baseWin->GetVisibility(&visible);
+  return visible;
+}
+
+bool nsFocusManager::IsNonFocusableRoot(nsIContent* aContent) {
+  MOZ_ASSERT(aContent, "aContent must not be NULL");
+  MOZ_ASSERT(aContent->IsInComposedDoc(), "aContent must be in a document");
+
+  // If the uncomposed document of aContent is in designMode, the root element
+  // is not focusable.
+  // NOTE: Most elements whose uncomposed document is in design mode are not
+  //       focusable, just the document is focusable.  However, if it's in a
+  //       shadow tree, it may be focus able even if the shadow host is in
+  //       design mode.
+  // Also, if aContent is not editable and it's not in designMode, it's not
+  // focusable.
+  // And in userfocusignored context nothing is focusable.
+  Document* doc = aContent->GetComposedDoc();
+  NS_ASSERTION(doc, "aContent must have current document");
+  return aContent == doc->GetRootElement() &&
+         (aContent->IsInDesignMode() || !aContent->IsEditable());
+}
+
+Element* nsFocusManager::FlushAndCheckIfFocusable(Element* aElement,
+                                                  uint32_t aFlags) {
+  if (!aElement) {
+    return nullptr;
+  }
+
+  nsCOMPtr<Document> doc = aElement->GetComposedDoc();
+  // can't focus elements that are not in documents
+  if (!doc) {
+    LOGCONTENT("Cannot focus %s because content not in document", aElement)
+    return nullptr;
+  }
+
+  // Make sure that our frames are up to date while ensuring the presshell is
+  // also initialized in case we come from a script calling focus() early.
+  mEventHandlingNeedsFlush = false;
+  doc->FlushPendingNotifications(FlushType::EnsurePresShellInitAndFrames);
+
+  PresShell* presShell = doc->GetPresShell();
+  if (!presShell) {
+    return nullptr;
+  }
+
+  // If this is an iframe that doesn't have an in-process subdocument, it is
+  // either an OOP iframe or an in-process iframe without lazy about:blank
+  // creation having taken place. In the OOP case, iframe is always focusable.
+  // In the in-process case, create the initial about:blank for in-process
+  // BrowsingContexts in order to have the `GetSubDocumentFor` call after this
+  // block return something.
+  //
+  // TODO(emilio): This block can probably go after bug 543435 lands.
+  if (RefPtr<nsFrameLoaderOwner> flo = do_QueryObject(aElement)) {
+    if (!aElement->IsXULElement()) {
+      // Only look at pre-existing browsing contexts. If this function is
+      // called during reflow, calling GetBrowsingContext() could cause frame
+      // loader initialization at a time when it isn't safe.
+      if (BrowsingContext* bc = flo->GetExtantBrowsingContext()) {
+        // This call may create a contentViewer-created about:blank.
+        // That's intentional, so we can move focus there.
+        Unused << bc->GetDocument();
+      }
+    }
+  }
+
+  return GetTheFocusableArea(aElement, aFlags);
+}
+
+bool nsFocusManager::Blur(BrowsingContext* aBrowsingContextToClear,
+                          BrowsingContext* aAncestorBrowsingContextToFocus,
+                          bool aIsLeavingDocument, bool aAdjustWidget,
+                          bool aRemainActive, uint64_t aActionId,
+                          Element* aElementToFocus) {
+  if (XRE_IsParentProcess()) {
+    return BlurImpl(aBrowsingContextToClear, aAncestorBrowsingContextToFocus,
+                    aIsLeavingDocument, aAdjustWidget, aRemainActive,
+                    aElementToFocus, aActionId);
+  }
+  mozilla::dom::ContentChild* contentChild =
+      mozilla::dom::ContentChild::GetSingleton();
+  MOZ_ASSERT(contentChild);
+  bool windowToClearHandled = false;
+  bool ancestorWindowToFocusHandled = false;
+
+  RefPtr<BrowsingContext> focusedBrowsingContext = GetFocusedBrowsingContext();
+  if (focusedBrowsingContext && focusedBrowsingContext->IsDiscarded()) {
+    focusedBrowsingContext = nullptr;
+  }
+  if (!focusedBrowsingContext) {
+    mFocusedElement = nullptr;
+    return true;
+  }
+  if (aBrowsingContextToClear && aBrowsingContextToClear->IsDiscarded()) {
+    aBrowsingContextToClear = nullptr;
+  }
+  if (aAncestorBrowsingContextToFocus &&
+      aAncestorBrowsingContextToFocus->IsDiscarded()) {
+    aAncestorBrowsingContextToFocus = nullptr;
+  }
+  // XXX should more early returns from BlurImpl be hoisted here to avoid
+  // processing aBrowsingContextToClear and aAncestorBrowsingContextToFocus in
+  // other processes when BlurImpl returns early in this process? Or should the
+  // IPC messages for those be sent by BlurImpl itself, in which case they could
+  // arrive late?
+  if (focusedBrowsingContext->IsInProcess()) {
+    if (aBrowsingContextToClear && !aBrowsingContextToClear->IsInProcess()) {
+      MOZ_RELEASE_ASSERT(!(aAncestorBrowsingContextToFocus &&
+                           !aAncestorBrowsingContextToFocus->IsInProcess()),
+                         "Both aBrowsingContextToClear and "
+                         "aAncestorBrowsingContextToFocus are "
+                         "out-of-process.");
+      contentChild->SendSetFocusedElement(aBrowsingContextToClear, false);
+    }
+    if (aAncestorBrowsingContextToFocus &&
+        !aAncestorBrowsingContextToFocus->IsInProcess()) {
+      contentChild->SendSetFocusedElement(aAncestorBrowsingContextToFocus,
+                                          true);
+    }
+    return BlurImpl(aBrowsingContextToClear, aAncestorBrowsingContextToFocus,
+                    aIsLeavingDocument, aAdjustWidget, aRemainActive,
+                    aElementToFocus, aActionId);
+  }
+  if (aBrowsingContextToClear && aBrowsingContextToClear->IsInProcess()) {
+    nsPIDOMWindowOuter* windowToClear = aBrowsingContextToClear->GetDOMWindow();
+    MOZ_ASSERT(windowToClear);
+    windowToClear->SetFocusedElement(nullptr);
+    windowToClearHandled = true;
+  }
+  if (aAncestorBrowsingContextToFocus &&
+      aAncestorBrowsingContextToFocus->IsInProcess()) {
+    nsPIDOMWindowOuter* ancestorWindowToFocus =
+        aAncestorBrowsingContextToFocus->GetDOMWindow();
+    MOZ_ASSERT(ancestorWindowToFocus);
+    ancestorWindowToFocus->SetFocusedElement(nullptr, 0, true);
+    ancestorWindowToFocusHandled = true;
+  }
+  // The expectation is that the blurring would eventually result in an IPC
+  // message doing this anyway, but this doesn't happen if the focus is in OOP
+  // iframe which won't try to bounce an IPC message to its parent frame.
+  SetFocusedWindowInternal(nullptr, aActionId);
+  contentChild->SendBlurToParent(
+      focusedBrowsingContext, aBrowsingContextToClear,
+      aAncestorBrowsingContextToFocus, aIsLeavingDocument, aAdjustWidget,
+      windowToClearHandled, ancestorWindowToFocusHandled, aActionId);
+  return true;
+}
+
+void nsFocusManager::BlurFromOtherProcess(
+    mozilla::dom::BrowsingContext* aFocusedBrowsingContext,
+    mozilla::dom::BrowsingContext* aBrowsingContextToClear,
+    mozilla::dom::BrowsingContext* aAncestorBrowsingContextToFocus,
+    bool aIsLeavingDocument, bool aAdjustWidget, uint64_t aActionId) {
+  if (aFocusedBrowsingContext != GetFocusedBrowsingContext()) {
+    return;
+  }
+  BlurImpl(aBrowsingContextToClear, aAncestorBrowsingContextToFocus,
+           aIsLeavingDocument, aAdjustWidget, /* aRemainActive = */ false,
+           nullptr, aActionId);
+}
+
+bool nsFocusManager::BlurImpl(BrowsingContext* aBrowsingContextToClear,
+                              BrowsingContext* aAncestorBrowsingContextToFocus,
+                              bool aIsLeavingDocument, bool aAdjustWidget,
+                              bool aRemainActive, Element* aElementToFocus,
+                              uint64_t aActionId) {
+  LOGFOCUS(("<<Blur begin actionid: %" PRIu64 ">>", aActionId));
+
+  // hold a reference to the focused content, which may be null
+  RefPtr<Element> element = mFocusedElement;
+  if (element) {
+    if (!element->IsInComposedDoc()) {
+      mFocusedElement = nullptr;
+      return true;
+    }
+    if (element == mFirstBlurEvent) {
+      return true;
+    }
+  }
+
+  RefPtr<BrowsingContext> focusedBrowsingContext = GetFocusedBrowsingContext();
+  // hold a reference to the focused window
+  nsCOMPtr<nsPIDOMWindowOuter> window;
+  if (focusedBrowsingContext) {
+    window = focusedBrowsingContext->GetDOMWindow();
+  }
+  if (!window) {
+    mFocusedElement = nullptr;
+    return true;
+  }
+
+  nsCOMPtr<nsIDocShell> docShell = window->GetDocShell();
+  if (!docShell) {
+    if (XRE_IsContentProcess() &&
+        ActionIdComparableAndLower(
+            aActionId, mActionIdForFocusedBrowsingContextInContent)) {
+      // Unclear if this ever happens.
+      LOGFOCUS(
+          ("Ignored an attempt to null out focused BrowsingContext when "
+           "docShell is null due to a stale action id %" PRIu64 ".",
+           aActionId));
+      return true;
+    }
+
+    mFocusedWindow = nullptr;
+    // Setting focused BrowsingContext to nullptr to avoid leaking in print
+    // preview.
+    SetFocusedBrowsingContext(nullptr, aActionId);
+    mFocusedElement = nullptr;
+    return true;
+  }
+
+  // Keep a ref to presShell since dispatching the DOM event may cause
+  // the document to be destroyed.
+  RefPtr<PresShell> presShell = docShell->GetPresShell();
+  if (!presShell) {
+    if (XRE_IsContentProcess() &&
+        ActionIdComparableAndLower(
+            aActionId, mActionIdForFocusedBrowsingContextInContent)) {
+      // Unclear if this ever happens.
+      LOGFOCUS(
+          ("Ignored an attempt to null out focused BrowsingContext when "
+           "presShell is null due to a stale action id %" PRIu64 ".",
+           aActionId));
+      return true;
+    }
+    mFocusedElement = nullptr;
+    mFocusedWindow = nullptr;
+    // Setting focused BrowsingContext to nullptr to avoid leaking in print
+    // preview.
+    SetFocusedBrowsingContext(nullptr, aActionId);
+    return true;
+  }
+
+  Maybe<AutoRestore<RefPtr<Element>>> ar;
+  if (!mFirstBlurEvent) {
+    ar.emplace(mFirstBlurEvent);
+    mFirstBlurEvent = element;
+  }
+
+  const RefPtr<nsPresContext> focusedPresContext =
+      GetActiveBrowsingContext() ? presShell->GetPresContext() : nullptr;
+  IMEStateManager::OnChangeFocus(focusedPresContext, nullptr,
+                                 GetFocusMoveActionCause(0));
+
+  // now adjust the actual focus, by clearing the fields in the focus manager
+  // and in the window.
+  mFocusedElement = nullptr;
+  if (aBrowsingContextToClear) {
+    nsPIDOMWindowOuter* windowToClear = aBrowsingContextToClear->GetDOMWindow();
+    if (windowToClear) {
+      windowToClear->SetFocusedElement(nullptr);
+    }
+  }
+
+  LOGCONTENT("Element %s has been blurred", element.get());
+
+  // Don't fire blur event on the root content which isn't editable.
+  bool sendBlurEvent =
+      element && element->IsInComposedDoc() && !IsNonFocusableRoot(element);
+  if (element) {
+    if (sendBlurEvent) {
+      NotifyFocusStateChange(element, aElementToFocus, 0, false, false);
+    }
+
+    if (!aRemainActive) {
+      bool windowBeingLowered = !aBrowsingContextToClear &&
+                                !aAncestorBrowsingContextToFocus &&
+                                aIsLeavingDocument && aAdjustWidget;
+      // If the object being blurred is a remote browser, deactivate remote
+      // content
+      if (BrowserParent* remote = BrowserParent::GetFrom(element)) {
+        MOZ_ASSERT(XRE_IsParentProcess());
+        // Let's deactivate all remote browsers.
+        BrowsingContext* topLevelBrowsingContext = remote->GetBrowsingContext();
+        topLevelBrowsingContext->PreOrderWalk([&](BrowsingContext* aContext) {
+          if (WindowGlobalParent* windowGlobalParent =
+                  aContext->Canonical()->GetCurrentWindowGlobal()) {
+            if (RefPtr<BrowserParent> browserParent =
+                    windowGlobalParent->GetBrowserParent()) {
+              browserParent->Deactivate(windowBeingLowered, aActionId);
+              LOGFOCUS(
+                  ("%s remote browser deactivated %p, %d, actionid: %" PRIu64,
+                   aContext == topLevelBrowsingContext ? "Top-level"
+                                                       : "OOP iframe",
+                   browserParent.get(), windowBeingLowered, aActionId));
+            }
+          }
+        });
+      }
+
+      // Same as above but for out-of-process iframes
+      if (BrowserBridgeChild* bbc = BrowserBridgeChild::GetFrom(element)) {
+        bbc->Deactivate(windowBeingLowered, aActionId);
+        LOGFOCUS(
+            ("Out-of-process iframe deactivated %p, %d, actionid: %" PRIu64,
+             bbc, windowBeingLowered, aActionId));
+      }
+    }
+  }
+
+  bool result = true;
+  if (sendBlurEvent) {
+    // if there is an active window, update commands. If there isn't an active
+    // window, then this was a blur caused by the active window being lowered,
+    // so there is no need to update the commands
+    if (GetActiveBrowsingContext()) {
+      window->UpdateCommands(u"focus"_ns, nullptr, 0);
+    }
+
+    SendFocusOrBlurEvent(eBlur, presShell, element->GetComposedDoc(), element,
+                         false, false, aElementToFocus);
+  }
+
+  // if we are leaving the document or the window was lowered, make the caret
+  // invisible.
+  if (aIsLeavingDocument || !GetActiveBrowsingContext()) {
+    SetCaretVisible(presShell, false, nullptr);
+  }
+
+  RefPtr<AccessibleCaretEventHub> eventHub =
+      presShell->GetAccessibleCaretEventHub();
+  if (eventHub) {
+    eventHub->NotifyBlur(aIsLeavingDocument || !GetActiveBrowsingContext());
+  }
+
+  // at this point, it is expected that this window will be still be
+  // focused, but the focused element will be null, as it was cleared before
+  // the event. If this isn't the case, then something else was focused during
+  // the blur event above and we should just return. However, if
+  // aIsLeavingDocument is set, a new document is desired, so make sure to
+  // blur the document and window.
+  if (GetFocusedBrowsingContext() != window->GetBrowsingContext() ||
+      (mFocusedElement != nullptr && !aIsLeavingDocument)) {
+    result = false;
+  } else if (aIsLeavingDocument) {
+    window->TakeFocus(false, 0);
+
+    // clear the focus so that the ancestor frame hierarchy is in the correct
+    // state. Pass true because aAncestorBrowsingContextToFocus is thought to be
+    // focused at this point.
+    if (aAncestorBrowsingContextToFocus) {
+      nsPIDOMWindowOuter* ancestorWindowToFocus =
+          aAncestorBrowsingContextToFocus->GetDOMWindow();
+      if (ancestorWindowToFocus) {
+        ancestorWindowToFocus->SetFocusedElement(nullptr, 0, true);
+      }
+    }
+
+    SetFocusedWindowInternal(nullptr, aActionId);
+    mFocusedElement = nullptr;
+
+    RefPtr<Document> doc = window->GetExtantDoc();
+    if (doc) {
+      SendFocusOrBlurEvent(eBlur, presShell, doc,
+                           MOZ_KnownLive(ToSupports(doc)), false);
+    }
+    if (!GetFocusedBrowsingContext()) {
+      nsCOMPtr<nsPIDOMWindowInner> innerWindow =
+          window->GetCurrentInnerWindow();
+      SendFocusOrBlurEvent(eBlur, presShell, doc, innerWindow, false);
+    }
+
+    // check if a different window was focused
+    result = (!GetFocusedBrowsingContext() && GetActiveBrowsingContext());
+  } else if (GetActiveBrowsingContext()) {
+    // Otherwise, the blur of the element without blurring the document
+    // occurred normally. Call UpdateCaret to redisplay the caret at the right
+    // location within the document. This is needed to ensure that the caret
+    // used for caret browsing is made visible again when an input field is
+    // blurred.
+    UpdateCaret(false, true, nullptr);
+  }
+
+  return result;
+}
+
+void nsFocusManager::ActivateRemoteFrameIfNeeded(Element& aElement,
+                                                 uint64_t aActionId) {
+  if (BrowserParent* remote = BrowserParent::GetFrom(&aElement)) {
+    remote->Activate(aActionId);
+    LOGFOCUS(
+        ("Remote browser activated %p, actionid: %" PRIu64, remote, aActionId));
+  }
+
+  // Same as above but for out-of-process iframes
+  if (BrowserBridgeChild* bbc = BrowserBridgeChild::GetFrom(&aElement)) {
+    bbc->Activate(aActionId);
+    LOGFOCUS(("Out-of-process iframe activated %p, actionid: %" PRIu64, bbc,
+              aActionId));
+  }
+}
+
+void nsFocusManager::Focus(
+    nsPIDOMWindowOuter* aWindow, Element* aElement, uint32_t aFlags,
+    bool aIsNewDocument, bool aFocusChanged, bool aWindowRaised,
+    bool aAdjustWidget, uint64_t aActionId,
+    const Maybe<BlurredElementInfo>& aBlurredElementInfo) {
+  LOGFOCUS(("<<Focus begin actionid: %" PRIu64 ">>", aActionId));
+
+  if (!aWindow) {
+    return;
+  }
+
+  if (aElement &&
+      (aElement == mFirstFocusEvent || aElement == mFirstBlurEvent)) {
+    return;
+  }
+
+  // Keep a reference to the presShell since dispatching the DOM event may
+  // cause the document to be destroyed.
+  nsCOMPtr<nsIDocShell> docShell = aWindow->GetDocShell();
+  if (!docShell) {
+    return;
+  }
+
+  const RefPtr<PresShell> presShell = docShell->GetPresShell();
+  if (!presShell) {
+    return;
+  }
+
+  bool focusInOtherContentProcess = false;
+  // Keep mochitest-browser-chrome harness happy by ignoring
+  // focusInOtherContentProcess in the chrome process, because the harness
+  // expects that.
+  if (!XRE_IsParentProcess()) {
+    if (RefPtr<nsFrameLoaderOwner> flo = do_QueryObject(aElement)) {
+      // Only look at pre-existing browsing contexts. If this function is
+      // called during reflow, calling GetBrowsingContext() could cause frame
+      // loader initialization at a time when it isn't safe.
+      if (BrowsingContext* bc = flo->GetExtantBrowsingContext()) {
+        focusInOtherContentProcess = !bc->IsInProcess();
+      }
+    }
+
+    if (ActionIdComparableAndLower(
+            aActionId, mActionIdForFocusedBrowsingContextInContent)) {
+      // Unclear if this ever happens.
+      LOGFOCUS(
+          ("Ignored an attempt to focus an element due to stale action id "
+           "%" PRIu64 ".",
+           aActionId));
+      return;
+    }
+  }
+
+  // If the focus actually changed, set the focus method (mouse, keyboard, etc).
+  // Otherwise, just get the current focus method and use that. This ensures
+  // that the method is set during the document and window focus events.
+  uint32_t focusMethod = aFocusChanged
+                             ? aFlags & METHODANDRING_MASK
+                             : aWindow->GetFocusMethod() |
+                                   (aFlags & (FLAG_SHOWRING | FLAG_NOSHOWRING));
+
+  if (!IsWindowVisible(aWindow)) {
+    // if the window isn't visible, for instance because it is a hidden tab,
+    // update the current focus and scroll it into view but don't do anything
+    // else
+    if (RefPtr elementToFocus = FlushAndCheckIfFocusable(aElement, aFlags)) {
+      aWindow->SetFocusedElement(elementToFocus, focusMethod);
+      if (aFocusChanged) {
+        ScrollIntoView(presShell, elementToFocus, aFlags);
+      }
+    }
+    return;
+  }
+
+  Maybe<AutoRestore<RefPtr<Element>>> ar;
+  if (!mFirstFocusEvent) {
+    ar.emplace(mFirstFocusEvent);
+    mFirstFocusEvent = aElement;
+  }
+
+  LOGCONTENT("Element %s has been focused", aElement);
+
+  if (MOZ_LOG_TEST(gFocusLog, LogLevel::Debug)) {
+    Document* docm = aWindow->GetExtantDoc();
+    if (docm) {
+      LOGCONTENT(" from %s", docm->GetRootElement());
+    }
+    LOGFOCUS(
+        (" [Newdoc: %d FocusChanged: %d Raised: %d Flags: %x actionid: %" PRIu64
+         "]",
+         aIsNewDocument, aFocusChanged, aWindowRaised, aFlags, aActionId));
+  }
+
+  if (aIsNewDocument) {
+    // if this is a new document, update the parent chain of frames so that
+    // focus can be traversed from the top level down to the newly focused
+    // window.
+    RefPtr<BrowsingContext> bc = aWindow->GetBrowsingContext();
+    AdjustWindowFocus(bc, false, IsWindowVisible(aWindow), aActionId);
+  }
+
+  // indicate that the window has taken focus.
+  if (aWindow->TakeFocus(true, focusMethod)) {
+    aIsNewDocument = true;
+  }
+
+  SetFocusedWindowInternal(aWindow, aActionId);
+
+  if (aAdjustWidget && !sTestMode) {
+    if (nsViewManager* vm = presShell->GetViewManager()) {
+      nsCOMPtr<nsIWidget> widget = vm->GetRootWidget();
+      if (widget)
+        widget->SetFocus(nsIWidget::Raise::No, aFlags & FLAG_NONSYSTEMCALLER
+                                                   ? CallerType::NonSystem
+                                                   : CallerType::System);
+    }
+  }
+
+  // if switching to a new document, first fire the focus event on the
+  // document and then the window.
+  if (aIsNewDocument) {
+    RefPtr<Document> doc = aWindow->GetExtantDoc();
+    // The focus change should be notified to IMEStateManager from here if:
+    // * the focused element is in design mode or
+    // * nobody gets focus and the document is in design mode
+    // since any element whose uncomposed document is in design mode won't
+    // receive focus event.
+    if (doc && ((aElement && aElement->IsInDesignMode()) ||
+                (!aElement && doc->IsInDesignMode()))) {
+      RefPtr<nsPresContext> presContext = presShell->GetPresContext();
+      IMEStateManager::OnChangeFocus(presContext, nullptr,
+                                     GetFocusMoveActionCause(aFlags));
+    }
+    if (doc && !focusInOtherContentProcess) {
+      SendFocusOrBlurEvent(eFocus, presShell, doc,
+                           MOZ_KnownLive(ToSupports(doc)), aWindowRaised);
+    }
+    if (GetFocusedBrowsingContext() == aWindow->GetBrowsingContext() &&
+        !mFocusedElement && !focusInOtherContentProcess) {
+      nsCOMPtr<nsPIDOMWindowInner> innerWindow =
+          aWindow->GetCurrentInnerWindow();
+      SendFocusOrBlurEvent(eFocus, presShell, doc, innerWindow, aWindowRaised);
+    }
+  }
+
+  // check to ensure that the element is still focusable, and that nothing
+  // else was focused during the events above.
+  // Note that the focusing element may have already been moved to another
+  // document/window.  In that case, we should stop setting focus to it
+  // because setting focus to the new window would cause redirecting focus
+  // again and again.
+  RefPtr elementToFocus =
+      aElement && aElement->IsInComposedDoc() &&
+              aElement->GetComposedDoc() == aWindow->GetExtantDoc()
+          ? FlushAndCheckIfFocusable(aElement, aFlags)
+          : nullptr;
+  if (elementToFocus && !mFocusedElement &&
+      GetFocusedBrowsingContext() == aWindow->GetBrowsingContext()) {
+    mFocusedElement = elementToFocus;
+
+    nsIContent* focusedNode = aWindow->GetFocusedElement();
+    const bool sendFocusEvent = elementToFocus->IsInComposedDoc() &&
+                                !IsNonFocusableRoot(elementToFocus);
+    const bool isRefocus = focusedNode && focusedNode == elementToFocus;
+    const bool shouldShowFocusRing =
+        sendFocusEvent &&
+        ShouldMatchFocusVisible(aWindow, *elementToFocus, aFlags);
+
+    aWindow->SetFocusedElement(elementToFocus, focusMethod, false);
+
+    const RefPtr<nsPresContext> presContext = presShell->GetPresContext();
+    if (sendFocusEvent) {
+      NotifyFocusStateChange(elementToFocus, nullptr, aFlags,
+                             /* aGettingFocus = */ true, shouldShowFocusRing);
+
+      // If this is a remote browser, focus its widget and activate remote
+      // content.  Note that we might no longer be in the same document,
+      // due to the events we fired above when aIsNewDocument.
+      if (presShell->GetDocument() == elementToFocus->GetComposedDoc()) {
+        ActivateRemoteFrameIfNeeded(*elementToFocus, aActionId);
+      }
+
+      IMEStateManager::OnChangeFocus(presContext, elementToFocus,
+                                     GetFocusMoveActionCause(aFlags));
+
+      // as long as this focus wasn't because a window was raised, update the
+      // commands
+      // XXXndeakin P2 someone could adjust the focus during the update
+      if (!aWindowRaised) {
+        aWindow->UpdateCommands(u"focus"_ns, nullptr, 0);
+      }
+
+      // If the focused element changed, scroll it into view
+      if (aFocusChanged) {
+        ScrollIntoView(presShell, elementToFocus, aFlags);
+      }
+
+      if (!focusInOtherContentProcess) {
+        RefPtr<Document> composedDocument = elementToFocus->GetComposedDoc();
+        RefPtr<Element> relatedTargetElement =
+            aBlurredElementInfo ? aBlurredElementInfo->mElement.get() : nullptr;
+        SendFocusOrBlurEvent(eFocus, presShell, composedDocument,
+                             elementToFocus, aWindowRaised, isRefocus,
+                             relatedTargetElement);
+      }
+    } else {
+      // We should notify IMEStateManager of actual focused element even if it
+      // won't get focus event because the other IMEStateManager users do not
+      // want to depend on this check, but IMEStateManager wants to verify
+      // passed focused element for avoidng to overrride nested calls.
+      IMEStateManager::OnChangeFocus(presContext, elementToFocus,
+                                     GetFocusMoveActionCause(aFlags));
+      if (!aWindowRaised) {
+        aWindow->UpdateCommands(u"focus"_ns, nullptr, 0);
+      }
+      if (aFocusChanged) {
+        // If the focused element changed, scroll it into view
+        ScrollIntoView(presShell, elementToFocus, aFlags);
+      }
+    }
+  } else {
+    if (!mFocusedElement && mFocusedWindow == aWindow) {
+      // When there is no focused element, IMEStateManager needs to adjust IME
+      // enabled state with the document.
+      RefPtr<nsPresContext> presContext = presShell->GetPresContext();
+      IMEStateManager::OnChangeFocus(presContext, nullptr,
+                                     GetFocusMoveActionCause(aFlags));
+    }
+
+    if (!aWindowRaised) {
+      aWindow->UpdateCommands(u"focus"_ns, nullptr, 0);
+    }
+  }
+
+  // update the caret visibility and position to match the newly focused
+  // element. However, don't update the position if this was a focus due to a
+  // mouse click as the selection code would already have moved the caret as
+  // needed. If this is a different document than was focused before, also
+  // update the caret's visibility. If this is the same document, the caret
+  // visibility should be the same as before so there is no need to update it.
+  if (mFocusedElement == elementToFocus) {
+    RefPtr<Element> focusedElement = mFocusedElement;
+    UpdateCaret(aFocusChanged && !(aFlags & FLAG_BYMOUSE), aIsNewDocument,
+                focusedElement);
+  }
+}
+
+class FocusBlurEvent : public Runnable {
+ public:
+  FocusBlurEvent(nsISupports* aTarget, EventMessage aEventMessage,
+                 nsPresContext* aContext, bool aWindowRaised, bool aIsRefocus,
+                 EventTarget* aRelatedTarget)
+      : mozilla::Runnable("FocusBlurEvent"),
+        mTarget(aTarget),
+        mContext(aContext),
+        mEventMessage(aEventMessage),
+        mWindowRaised(aWindowRaised),
+        mIsRefocus(aIsRefocus),
+        mRelatedTarget(aRelatedTarget) {}
+
+  // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230, bug 1535398)
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHOD Run() override {
+    InternalFocusEvent event(true, mEventMessage);
+    event.mFlags.mBubbles = false;
+    event.mFlags.mCancelable = false;
+    event.mFromRaise = mWindowRaised;
+    event.mIsRefocus = mIsRefocus;
+    event.mRelatedTarget = mRelatedTarget;
+    return EventDispatcher::Dispatch(mTarget, mContext, &event);
+  }
+
+  const nsCOMPtr<nsISupports> mTarget;
+  const RefPtr<nsPresContext> mContext;
+  EventMessage mEventMessage;
+  bool mWindowRaised;
+  bool mIsRefocus;
+  nsCOMPtr<EventTarget> mRelatedTarget;
+};
+
+class FocusInOutEvent : public Runnable {
+ public:
+  FocusInOutEvent(nsISupports* aTarget, EventMessage aEventMessage,
+                  nsPresContext* aContext,
+                  nsPIDOMWindowOuter* aOriginalFocusedWindow,
+                  nsIContent* aOriginalFocusedContent,
+                  EventTarget* aRelatedTarget)
+      : mozilla::Runnable("FocusInOutEvent"),
+        mTarget(aTarget),
+        mContext(aContext),
+        mEventMessage(aEventMessage),
+        mOriginalFocusedWindow(aOriginalFocusedWindow),
+        mOriginalFocusedContent(aOriginalFocusedContent),
+        mRelatedTarget(aRelatedTarget) {}
+
+  // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230, bug 1535398)
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHOD Run() override {
+    nsCOMPtr<nsIContent> originalWindowFocus =
+        mOriginalFocusedWindow ? mOriginalFocusedWindow->GetFocusedElement()
+                               : nullptr;
+    // Blink does not check that focus is the same after blur, but WebKit does.
+    // Opt to follow Blink's behavior (see bug 687787).
+    if (mEventMessage == eFocusOut ||
+        originalWindowFocus == mOriginalFocusedContent) {
+      InternalFocusEvent event(true, mEventMessage);
+      event.mFlags.mBubbles = true;
+      event.mFlags.mCancelable = false;
+      event.mRelatedTarget = mRelatedTarget;
+      return EventDispatcher::Dispatch(mTarget, mContext, &event);
+    }
+    return NS_OK;
+  }
+
+  const nsCOMPtr<nsISupports> mTarget;
+  const RefPtr<nsPresContext> mContext;
+  EventMessage mEventMessage;
+  nsCOMPtr<nsPIDOMWindowOuter> mOriginalFocusedWindow;
+  nsCOMPtr<nsIContent> mOriginalFocusedContent;
+  nsCOMPtr<EventTarget> mRelatedTarget;
+};
+
+static Document* GetDocumentHelper(EventTarget* aTarget) {
+  if (!aTarget) {
+    return nullptr;
+  }
+  if (const nsINode* node = nsINode::FromEventTarget(aTarget)) {
+    return node->OwnerDoc();
+  }
+  nsPIDOMWindowInner* win = nsPIDOMWindowInner::FromEventTarget(aTarget);
+  return win ? win->GetExtantDoc() : nullptr;
+}
+
+void nsFocusManager::FireFocusInOrOutEvent(
+    EventMessage aEventMessage, PresShell* aPresShell, nsISupports* aTarget,
+    nsPIDOMWindowOuter* aCurrentFocusedWindow,
+    nsIContent* aCurrentFocusedContent, EventTarget* aRelatedTarget) {
+  NS_ASSERTION(aEventMessage == eFocusIn || aEventMessage == eFocusOut,
+               "Wrong event type for FireFocusInOrOutEvent");
+
+  nsContentUtils::AddScriptRunner(new FocusInOutEvent(
+      aTarget, aEventMessage, aPresShell->GetPresContext(),
+      aCurrentFocusedWindow, aCurrentFocusedContent, aRelatedTarget));
+}
+
+void nsFocusManager::SendFocusOrBlurEvent(EventMessage aEventMessage,
+                                          PresShell* aPresShell,
+                                          Document* aDocument,
+                                          nsISupports* aTarget,
+                                          bool aWindowRaised, bool aIsRefocus,
+                                          EventTarget* aRelatedTarget) {
+  NS_ASSERTION(aEventMessage == eFocus || aEventMessage == eBlur,
+               "Wrong event type for SendFocusOrBlurEvent");
+
+  nsCOMPtr<EventTarget> eventTarget = do_QueryInterface(aTarget);
+  nsCOMPtr<Document> eventTargetDoc = GetDocumentHelper(eventTarget);
+  nsCOMPtr<Document> relatedTargetDoc = GetDocumentHelper(aRelatedTarget);
+
+  // set aRelatedTarget to null if it's not in the same document as eventTarget
+  if (eventTargetDoc != relatedTargetDoc) {
+    aRelatedTarget = nullptr;
+  }
+
+  if (aDocument && aDocument->EventHandlingSuppressed()) {
+    // if this event was already queued, remove it and append it to the end
+    mDelayedBlurFocusEvents.RemoveElementsBy([&](const auto& event) {
+      return event.mEventMessage == aEventMessage &&
+             event.mPresShell == aPresShell && event.mDocument == aDocument &&
+             event.mTarget == eventTarget &&
+             event.mRelatedTarget == aRelatedTarget;
+    });
+
+    mDelayedBlurFocusEvents.EmplaceBack(aEventMessage, aPresShell, aDocument,
+                                        eventTarget, aRelatedTarget);
+    return;
+  }
+
+  // If mDelayedBlurFocusEvents queue is not empty, check if there are events
+  // that belongs to this doc, if yes, fire them first.
+  if (aDocument && !aDocument->EventHandlingSuppressed() &&
+      mDelayedBlurFocusEvents.Length()) {
+    FireDelayedEvents(aDocument);
+  }
+
+  FireFocusOrBlurEvent(aEventMessage, aPresShell, aTarget, aWindowRaised,
+                       aIsRefocus, aRelatedTarget);
+}
+
+void nsFocusManager::FireFocusOrBlurEvent(EventMessage aEventMessage,
+                                          PresShell* aPresShell,
+                                          nsISupports* aTarget,
+                                          bool aWindowRaised, bool aIsRefocus,
+                                          EventTarget* aRelatedTarget) {
+  nsCOMPtr<nsPIDOMWindowOuter> currentWindow = mFocusedWindow;
+  nsCOMPtr<nsPIDOMWindowInner> targetWindow = do_QueryInterface(aTarget);
+  nsCOMPtr<Document> targetDocument = do_QueryInterface(aTarget);
+  nsCOMPtr<nsIContent> currentFocusedContent =
+      currentWindow ? currentWindow->GetFocusedElement() : nullptr;
+
+#ifdef ACCESSIBILITY
+  nsAccessibilityService* accService = GetAccService();
+  if (accService) {
+    if (aEventMessage == eFocus) {
+      accService->NotifyOfDOMFocus(aTarget);
+    } else {
+      accService->NotifyOfDOMBlur(aTarget);
+    }
+  }
+#endif
+
+  aPresShell->ScheduleContentRelevancyUpdate(
+      ContentRelevancyReason::FocusInSubtree);
+
+  nsContentUtils::AddScriptRunner(
+      new FocusBlurEvent(aTarget, aEventMessage, aPresShell->GetPresContext(),
+                         aWindowRaised, aIsRefocus, aRelatedTarget));
+
+  // Check that the target is not a window or document before firing
+  // focusin/focusout. Other browsers do not fire focusin/focusout on window,
+  // despite being required in the spec, so follow their behavior.
+  //
+  // As for document, we should not even fire focus/blur, but until then, we
+  // need this check. targetDocument should be removed once bug 1228802 is
+  // resolved.
+  if (!targetWindow && !targetDocument) {
+    EventMessage focusInOrOutMessage =
+        aEventMessage == eFocus ? eFocusIn : eFocusOut;
+    FireFocusInOrOutEvent(focusInOrOutMessage, aPresShell, aTarget,
+                          currentWindow, currentFocusedContent, aRelatedTarget);
+  }
+}
+
+void nsFocusManager::ScrollIntoView(PresShell* aPresShell, nsIContent* aContent,
+                                    uint32_t aFlags) {
+  if (aFlags & FLAG_NOSCROLL) {
+    return;
+  }
+  // If the noscroll flag isn't set, scroll the newly focused element into view.
+  aPresShell->ScrollContentIntoView(
+      aContent, ScrollAxis(WhereToScroll::Nearest, WhenToScroll::IfNotVisible),
+      ScrollAxis(WhereToScroll::Nearest, WhenToScroll::IfNotVisible),
+      ScrollFlags::ScrollOverflowHidden);
+  // Scroll the input / textarea selection into view, unless focused with the
+  // mouse, see bug 572649.
+  if (aFlags & FLAG_BYMOUSE) {
+    return;
+  }
+  // ScrollContentIntoView flushes layout, so no need to flush again here.
+  if (nsTextControlFrame* tf = do_QueryFrame(aContent->GetPrimaryFrame())) {
+    tf->ScrollSelectionIntoViewAsync(nsTextControlFrame::ScrollAncestors::Yes);
+  }
+}
+
+void nsFocusManager::RaiseWindow(nsPIDOMWindowOuter* aWindow,
+                                 CallerType aCallerType, uint64_t aActionId) {
+  // don't raise windows that are already raised or are in the process of
+  // being lowered
+
+  if (!aWindow || aWindow == mWindowBeingLowered) {
+    return;
+  }
+
+  if (XRE_IsParentProcess()) {
+    if (aWindow == mActiveWindow) {
+      return;
+    }
+  } else {
+    BrowsingContext* bc = aWindow->GetBrowsingContext();
+    // TODO: Deeper OOP frame hierarchies are
+    // https://bugzilla.mozilla.org/show_bug.cgi?id=1661227
+    if (bc == GetActiveBrowsingContext()) {
+      return;
+    }
+    if (bc == GetFocusedBrowsingContext()) {
+      return;
+    }
+  }
+
+  if (sTestMode) {
+    // In test mode, emulate raising the window. WindowRaised takes
+    // care of lowering the present active window. This happens in
+    // a separate runnable to avoid touching multiple windows in
+    // the current runnable.
+
+    nsCOMPtr<nsPIDOMWindowOuter> window(aWindow);
+    RefPtr<nsFocusManager> self(this);
+    NS_DispatchToCurrentThread(NS_NewRunnableFunction(
+        "nsFocusManager::RaiseWindow",
+        // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1770093)
+        [self, window]() MOZ_CAN_RUN_SCRIPT_BOUNDARY -> void {
+          self->WindowRaised(window, GenerateFocusActionId());
+        }));
+    return;
+  }
+
+  if (XRE_IsContentProcess()) {
+    BrowsingContext* bc = aWindow->GetBrowsingContext();
+    if (!bc->IsTop()) {
+      // Assume the raise below will succeed and run the raising synchronously
+      // in this process to make the focus event that is observable in this
+      // process fire in the right order relative to mouseup when we are here
+      // thanks to a mousedown.
+      WindowRaised(aWindow, aActionId);
+    }
+  }
+
+#if defined(XP_WIN)
+  // Windows would rather we focus the child widget, otherwise, the toplevel
+  // widget will always end up being focused. Fortunately, focusing the child
+  // widget will also have the effect of raising the window this widget is in.
+  // But on other platforms, we can just focus the toplevel widget to raise
+  // the window.
+  nsCOMPtr<nsPIDOMWindowOuter> childWindow;
+  GetFocusedDescendant(aWindow, eIncludeAllDescendants,
+                       getter_AddRefs(childWindow));
+  if (!childWindow) {
+    childWindow = aWindow;
+  }
+
+  nsCOMPtr<nsIDocShell> docShell = aWindow->GetDocShell();
+  if (!docShell) {
+    return;
+  }
+
+  PresShell* presShell = docShell->GetPresShell();
+  if (!presShell) {
+    return;
+  }
+
+  if (nsViewManager* vm = presShell->GetViewManager()) {
+    nsCOMPtr<nsIWidget> widget = vm->GetRootWidget();
+    if (widget) {
+      widget->SetFocus(nsIWidget::Raise::Yes, aCallerType);
+    }
+  }
+#else
+  nsCOMPtr<nsIBaseWindow> treeOwnerAsWin =
+      do_QueryInterface(aWindow->GetDocShell());
+  if (treeOwnerAsWin) {
+    nsCOMPtr<nsIWidget> widget;
+    treeOwnerAsWin->GetMainWidget(getter_AddRefs(widget));
+    if (widget) {
+      widget->SetFocus(nsIWidget::Raise::Yes, aCallerType);
+    }
+  }
+#endif
+}
+
+void nsFocusManager::UpdateCaretForCaretBrowsingMode() {
+  RefPtr<Element> focusedElement = mFocusedElement;
+  UpdateCaret(false, true, focusedElement);
+}
+
+void nsFocusManager::UpdateCaret(bool aMoveCaretToFocus, bool aUpdateVisibility,
+                                 nsIContent* aContent) {
+  LOGFOCUS(("Update Caret: %d %d", aMoveCaretToFocus, aUpdateVisibility));
+
+  if (!mFocusedWindow) {
+    return;
+  }
+
+  // this is called when a document is focused or when the caretbrowsing
+  // preference is changed
+  nsCOMPtr<nsIDocShell> focusedDocShell = mFocusedWindow->GetDocShell();
+  if (!focusedDocShell) {
+    return;
+  }
+
+  if (focusedDocShell->ItemType() == nsIDocShellTreeItem::typeChrome) {
+    return;  // Never browse with caret in chrome
+  }
+
+  bool browseWithCaret = Preferences::GetBool("accessibility.browsewithcaret");
+
+  const RefPtr<PresShell> presShell = focusedDocShell->GetPresShell();
+  if (!presShell) {
+    return;
+  }
+
+  // If this is an editable document which isn't contentEditable, or a
+  // contentEditable document and the node to focus is contentEditable,
+  // return, so that we don't mess with caret visibility.
+  bool isEditable = false;
+  focusedDocShell->GetEditable(&isEditable);
+
+  if (isEditable) {
+    Document* doc = presShell->GetDocument();
+
+    bool isContentEditableDoc =
+        doc &&
+        doc->GetEditingState() == Document::EditingState::eContentEditable;
+
+    bool isFocusEditable = aContent && aContent->HasFlag(NODE_IS_EDITABLE);
+    if (!isContentEditableDoc || isFocusEditable) {
+      return;
+    }
+  }
+
+  if (!isEditable && aMoveCaretToFocus) {
+    MoveCaretToFocus(presShell, aContent);
+  }
+
+  // The above MoveCaretToFocus call may run scripts which
+  // may clear mFocusWindow
+  if (!mFocusedWindow) {
+    return;
+  }
+
+  if (!aUpdateVisibility) {
+    return;
+  }
+
+  // XXXndeakin this doesn't seem right. It should be checking for this only
+  // on the nearest ancestor frame which is a chrome frame. But this is
+  // what the existing code does, so just leave it for now.
+  if (!browseWithCaret) {
+    nsCOMPtr<Element> docElement = mFocusedWindow->GetFrameElementInternal();
+    if (docElement)
+      browseWithCaret = docElement->AttrValueIs(
+          kNameSpaceID_None, nsGkAtoms::showcaret, u"true"_ns, eCaseMatters);
+  }
+
+  SetCaretVisible(presShell, browseWithCaret, aContent);
+}
+
+void nsFocusManager::MoveCaretToFocus(PresShell* aPresShell,
+                                      nsIContent* aContent) {
+  nsCOMPtr<Document> doc = aPresShell->GetDocument();
+  if (doc) {
+    RefPtr<nsFrameSelection> frameSelection = aPresShell->FrameSelection();
+    RefPtr<Selection> domSelection =
+        frameSelection->GetSelection(SelectionType::eNormal);
+    if (domSelection) {
+      // First clear the selection. This way, if there is no currently focused
+      // content, the selection will just be cleared.
+      domSelection->RemoveAllRanges(IgnoreErrors());
+      if (aContent) {
+        ErrorResult rv;
+        RefPtr<nsRange> newRange = doc->CreateRange(rv);
+        if (NS_WARN_IF(rv.Failed())) {
+          rv.SuppressException();
+          return;
+        }
+
+        // Set the range to the start of the currently focused node
+        // Make sure it's collapsed
+        newRange->SelectNodeContents(*aContent, IgnoreErrors());
+
+        if (!aContent->GetFirstChild() ||
+            aContent->IsHTMLFormControlElement()) {
+          // If current focus node is a leaf, set range to before the
+          // node by using the parent as a container.
+          // This prevents it from appearing as selected.
+          newRange->SetStartBefore(*aContent, IgnoreErrors());
+          newRange->SetEndBefore(*aContent, IgnoreErrors());
+        }
+        domSelection->AddRangeAndSelectFramesAndNotifyListeners(*newRange,
+                                                                IgnoreErrors());
+        domSelection->CollapseToStart(IgnoreErrors());
+      }
+    }
+  }
+}
+
+nsresult nsFocusManager::SetCaretVisible(PresShell* aPresShell, bool aVisible,
+                                         nsIContent* aContent) {
+  // When browsing with caret, make sure caret is visible after new focus
+  // Return early if there is no caret. This can happen for the testcase
+  // for bug 308025 where a window is closed in a blur handler.
+  RefPtr<nsCaret> caret = aPresShell->GetCaret();
+  if (!caret) {
+    return NS_OK;
+  }
+
+  bool caretVisible = caret->IsVisible();
+  if (!aVisible && !caretVisible) {
+    return NS_OK;
+  }
+
+  RefPtr<nsFrameSelection> frameSelection;
+  if (aContent) {
+    NS_ASSERTION(aContent->GetComposedDoc() == aPresShell->GetDocument(),
+                 "Wrong document?");
+    nsIFrame* focusFrame = aContent->GetPrimaryFrame();
+    if (focusFrame) {
+      frameSelection = focusFrame->GetFrameSelection();
+    }
+  }
+
+  RefPtr<nsFrameSelection> docFrameSelection = aPresShell->FrameSelection();
+
+  if (docFrameSelection && caret &&
+      (frameSelection == docFrameSelection || !aContent)) {
+    Selection* domSelection =
+        docFrameSelection->GetSelection(SelectionType::eNormal);
+    if (domSelection) {
+      // First, hide the caret to prevent attempting to show it in
+      // SetCaretDOMSelection
+      aPresShell->SetCaretEnabled(false);
+
+      // Caret must blink on non-editable elements
+      caret->SetIgnoreUserModify(true);
+      // Tell the caret which selection to use
+      caret->SetSelection(domSelection);
+
+      // In content, we need to set the caret. The only special case is edit
+      // fields, which have a different frame selection from the document.
+      // They will take care of making the caret visible themselves.
+
+      aPresShell->SetCaretReadOnly(false);
+      aPresShell->SetCaretEnabled(aVisible);
+    }
+  }
+
+  return NS_OK;
+}
+
+nsresult nsFocusManager::GetSelectionLocation(Document* aDocument,
+                                              PresShell* aPresShell,
+                                              nsIContent** aStartContent,
+                                              nsIContent** aEndContent) {
+  *aStartContent = *aEndContent = nullptr;
+  nsPresContext* presContext = aPresShell->GetPresContext();
+  NS_ASSERTION(presContext, "mPresContent is null!!");
+
+  RefPtr<nsFrameSelection> frameSelection = aPresShell->FrameSelection();
+
+  RefPtr<Selection> domSelection;
+  if (frameSelection) {
+    domSelection = frameSelection->GetSelection(SelectionType::eNormal);
+  }
+
+  bool isCollapsed = false;
+  nsCOMPtr<nsIContent> startContent, endContent;
+  uint32_t startOffset = 0;
+  if (domSelection) {
+    isCollapsed = domSelection->IsCollapsed();
+    RefPtr<const nsRange> domRange = domSelection->GetRangeAt(0);
+    if (domRange) {
+      nsCOMPtr<nsINode> startNode = domRange->GetStartContainer();
+      nsCOMPtr<nsINode> endNode = domRange->GetEndContainer();
+      startOffset = domRange->StartOffset();
+
+      nsIContent* childContent = nullptr;
+
+      startContent = do_QueryInterface(startNode);
+      if (startContent && startContent->IsElement()) {
+        childContent = startContent->GetChildAt_Deprecated(startOffset);
+        if (childContent) {
+          startContent = childContent;
+        }
+      }
+
+      endContent = do_QueryInterface(endNode);
+      if (endContent && endContent->IsElement()) {
+        uint32_t endOffset = domRange->EndOffset();
+        childContent = endContent->GetChildAt_Deprecated(endOffset);
+        if (childContent) {
+          endContent = childContent;
+        }
+      }
+    }
+  } else {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsIFrame* startFrame = nullptr;
+  if (startContent) {
+    startFrame = startContent->GetPrimaryFrame();
+    if (isCollapsed) {
+      // Next check to see if our caret is at the very end of a node
+      // If so, the caret is actually sitting in front of the next
+      // logical frame's primary node - so for this case we need to
+      // change caretContent to that node.
+
+      if (startContent->NodeType() == nsINode::TEXT_NODE) {
+        nsAutoString nodeValue;
+        startContent->GetAsText()->AppendTextTo(nodeValue);
+
+        if (nodeValue.Length() == startOffset &&
+            !startContent->IsHTMLFormControlElement() &&
+            startContent != aDocument->GetRootElement()) {
+          // Yes, indeed we were at the end of the last node
+          nsCOMPtr<nsIFrameEnumerator> frameTraversal;
+          nsresult rv = NS_NewFrameTraversal(getter_AddRefs(frameTraversal),
+                                             presContext, startFrame, eLeaf,
+                                             false,  // aVisual
+                                             false,  // aLockInScrollView
+                                             true,   // aFollowOOFs
+                                             false   // aSkipPopupChecks
+          );
+          NS_ENSURE_SUCCESS(rv, rv);
+
+          nsIFrame* newCaretFrame = nullptr;
+          nsCOMPtr<nsIContent> newCaretContent = startContent;
+          bool endOfSelectionInStartNode(startContent == endContent);
+          do {
+            // Continue getting the next frame until the primary content for the
+            // frame we are on changes - we don't want to be stuck in the same
+            // place
+            frameTraversal->Next();
+            newCaretFrame =
+                static_cast<nsIFrame*>(frameTraversal->CurrentItem());
+            if (nullptr == newCaretFrame) break;
+            newCaretContent = newCaretFrame->GetContent();
+          } while (!newCaretContent || newCaretContent == startContent);
+
+          if (newCaretFrame && newCaretContent) {
+            // If the caret is exactly at the same position of the new frame,
+            // then we can use the newCaretFrame and newCaretContent for our
+            // position
+            nsRect caretRect;
+            nsIFrame* frame = nsCaret::GetGeometry(domSelection, &caretRect);
+            if (frame) {
+              nsPoint caretWidgetOffset;
+              nsIWidget* widget = frame->GetNearestWidget(caretWidgetOffset);
+              caretRect.MoveBy(caretWidgetOffset);
+              nsPoint newCaretOffset;
+              nsIWidget* newCaretWidget =
+                  newCaretFrame->GetNearestWidget(newCaretOffset);
+              if (widget == newCaretWidget && caretRect.y == newCaretOffset.y &&
+                  caretRect.x == newCaretOffset.x) {
+                // The caret is at the start of the new element.
+                startFrame = newCaretFrame;
+                startContent = newCaretContent;
+                if (endOfSelectionInStartNode) {
+                  endContent = newCaretContent;  // Ensure end of selection is
+                                                 // not before start
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+
+  *aStartContent = startContent;
+  *aEndContent = endContent;
+  NS_IF_ADDREF(*aStartContent);
+  NS_IF_ADDREF(*aEndContent);
+
+  return NS_OK;
+}
+
+nsresult nsFocusManager::DetermineElementToMoveFocus(
+    nsPIDOMWindowOuter* aWindow, nsIContent* aStartContent, int32_t aType,
+    bool aNoParentTraversal, bool aNavigateByKey, nsIContent** aNextContent) {
+  *aNextContent = nullptr;
+
+  // This is used for document navigation only. It will be set to true if we
+  // start navigating from a starting point. If this starting point is near the
+  // end of the document (for example, an element on a statusbar), and there
+  // are no child documents or panels before the end of the document, then we
+  // will need to ensure that we don't consider the root chrome window when we
+  // loop around and instead find the next child document/panel, as focus is
+  // already in that window. This flag will be cleared once we navigate into
+  // another document.
+  bool mayFocusRoot = (aStartContent != nullptr);
+
+  nsCOMPtr<nsIContent> startContent = aStartContent;
+  if (!startContent && aType != MOVEFOCUS_CARET) {
+    if (aType == MOVEFOCUS_FORWARDDOC || aType == MOVEFOCUS_BACKWARDDOC) {
+      // When moving between documents, make sure to get the right
+      // starting content in a descendant.
+      nsCOMPtr<nsPIDOMWindowOuter> focusedWindow;
+      startContent = GetFocusedDescendant(aWindow, eIncludeAllDescendants,
+                                          getter_AddRefs(focusedWindow));
+    } else if (aType != MOVEFOCUS_LASTDOC) {
+      // Otherwise, start at the focused node. If MOVEFOCUS_LASTDOC is used,
+      // then we are document-navigating backwards from chrome to the content
+      // process, and we don't want to use this so that we start from the end
+      // of the document.
+      startContent = aWindow->GetFocusedElement();
+    }
+  }
+
+  nsCOMPtr<Document> doc;
+  if (startContent)
+    doc = startContent->GetComposedDoc();
+  else
+    doc = aWindow->GetExtantDoc();
+  if (!doc) return NS_OK;
+
+  LookAndFeel::GetInt(LookAndFeel::IntID::TabFocusModel,
+                      &nsIContent::sTabFocusModel);
+
+  // True if we are navigating by document (F6/Shift+F6) or false if we are
+  // navigating by element (Tab/Shift+Tab).
+  const bool forDocumentNavigation =
+      aType == MOVEFOCUS_FORWARDDOC || aType == MOVEFOCUS_BACKWARDDOC ||
+      aType == MOVEFOCUS_FIRSTDOC || aType == MOVEFOCUS_LASTDOC;
+
+  // If moving to the root or first document, find the root element and return.
+  if (aType == MOVEFOCUS_ROOT || aType == MOVEFOCUS_FIRSTDOC) {
+    NS_IF_ADDREF(*aNextContent = GetRootForFocus(aWindow, doc, false, false));
+    if (!*aNextContent && aType == MOVEFOCUS_FIRSTDOC) {
+      // When looking for the first document, if the root wasn't focusable,
+      // find the next focusable document.
+      aType = MOVEFOCUS_FORWARDDOC;
+    } else {
+      return NS_OK;
+    }
+  }
+
+  // rootElement and presShell may be set to sub-document's ones so that they
+  // cannot be `const`.
+  RefPtr<Element> rootElement = doc->GetRootElement();
+  NS_ENSURE_TRUE(rootElement, NS_OK);
+
+  RefPtr<PresShell> presShell = doc->GetPresShell();
+  NS_ENSURE_TRUE(presShell, NS_OK);
+
+  if (aType == MOVEFOCUS_FIRST) {
+    if (!aStartContent) {
+      startContent = rootElement;
+    }
+    return GetNextTabbableContent(presShell, startContent, nullptr,
+                                  startContent, true, 1, false, false,
+                                  aNavigateByKey, aNextContent);
+  }
+  if (aType == MOVEFOCUS_LAST) {
+    if (!aStartContent) {
+      startContent = rootElement;
+    }
+    return GetNextTabbableContent(presShell, startContent, nullptr,
+                                  startContent, false, 0, false, false,
+                                  aNavigateByKey, aNextContent);
+  }
+
+  bool forward = (aType == MOVEFOCUS_FORWARD || aType == MOVEFOCUS_FORWARDDOC ||
+                  aType == MOVEFOCUS_CARET);
+  bool doNavigation = true;
+  bool ignoreTabIndex = false;
+  // when a popup is open, we want to ensure that tab navigation occurs only
+  // within the most recently opened panel. If a popup is open, its frame will
+  // be stored in popupFrame.
+  nsIFrame* popupFrame = nullptr;
+
+  int32_t tabIndex = forward ? 1 : 0;
+  if (startContent) {
+    nsIFrame* frame = startContent->GetPrimaryFrame();
+    if (startContent->IsHTMLElement(nsGkAtoms::area)) {
+      startContent->IsFocusable(&tabIndex);
+    } else if (frame) {
+      tabIndex = frame->IsFocusable().mTabIndex;
+    } else {
+      startContent->IsFocusable(&tabIndex);
+    }
+
+    // if the current element isn't tabbable, ignore the tabindex and just
+    // look for the next element. The root content won't have a tabindex
+    // so just treat this as the beginning of the tab order.
+    if (tabIndex < 0) {
+      tabIndex = 1;
+      if (startContent != rootElement) {
+        ignoreTabIndex = true;
+      }
+    }
+
+    // check if the focus is currently inside a popup. Elements such as the
+    // autocomplete widget use the noautofocus attribute to allow the focus to
+    // remain outside the popup when it is opened.
+    if (frame) {
+      popupFrame = nsLayoutUtils::GetClosestFrameOfType(
+          frame, LayoutFrameType::MenuPopup);
+    }
+
+    if (popupFrame && !forDocumentNavigation) {
+      // Don't navigate outside of a popup, so pretend that the
+      // root content is the popup itself
+      rootElement = popupFrame->GetContent()->AsElement();
+      NS_ASSERTION(rootElement, "Popup frame doesn't have a content node");
+    } else if (!forward) {
+      // If focus moves backward and when current focused node is root
+      // content or <body> element which is editable by contenteditable
+      // attribute, focus should move to its parent document.
+      if (startContent == rootElement) {
+        doNavigation = false;
+      } else {
+        Document* doc = startContent->GetComposedDoc();
+        if (startContent ==
+            nsLayoutUtils::GetEditableRootContentByContentEditable(doc)) {
+          doNavigation = false;
+        }
+      }
+    }
+  } else {
+    if (aType != MOVEFOCUS_CARET) {
+      // if there is no focus, yet a panel is open, focus the first item in
+      // the panel
+      nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+      if (pm) {
+        popupFrame = pm->GetTopPopup(PopupType::Panel);
+      }
+    }
+    if (popupFrame) {
+      // When there is a popup open, and no starting content, start the search
+      // at the topmost popup.
+      startContent = popupFrame->GetContent();
+      NS_ASSERTION(startContent, "Popup frame doesn't have a content node");
+      // Unless we are searching for documents, set the root content to the
+      // popup as well, so that we don't tab-navigate outside the popup.
+      // When navigating by documents, we start at the popup but can navigate
+      // outside of it to look for other panels and documents.
+      if (!forDocumentNavigation) {
+        rootElement = startContent->AsElement();
+      }
+
+      doc = startContent ? startContent->GetComposedDoc() : nullptr;
+    } else {
+      // Otherwise, for content shells, start from the location of the caret.
+      nsCOMPtr<nsIDocShell> docShell = aWindow->GetDocShell();
+      if (docShell && docShell->ItemType() != nsIDocShellTreeItem::typeChrome) {
+        nsCOMPtr<nsIContent> endSelectionContent;
+        GetSelectionLocation(doc, presShell, getter_AddRefs(startContent),
+                             getter_AddRefs(endSelectionContent));
+        // If the selection is on the rootElement, then there is no selection
+        if (startContent == rootElement) {
+          startContent = nullptr;
+        }
+
+        if (aType == MOVEFOCUS_CARET) {
+          // GetFocusInSelection finds a focusable link near the caret.
+          // If there is no start content though, don't do this to avoid
+          // focusing something unexpected.
+          if (startContent) {
+            GetFocusInSelection(aWindow, startContent, endSelectionContent,
+                                aNextContent);
+          }
+          return NS_OK;
+        }
+
+        if (startContent) {
+          // when starting from a selection, we always want to find the next or
+          // previous element in the document. So the tabindex on elements
+          // should be ignored.
+          ignoreTabIndex = true;
+        }
+      }
+
+      if (!startContent) {
+        // otherwise, just use the root content as the starting point
+        startContent = rootElement;
+        NS_ENSURE_TRUE(startContent, NS_OK);
+      }
+    }
+  }
+
+  // Check if the starting content is the same as the content assigned to the
+  // retargetdocumentfocus attribute. Is so, we don't want to start searching
+  // from there but instead from the beginning of the document. Otherwise, the
+  // content that appears before the retargetdocumentfocus element will never
+  // get checked as it will be skipped when the focus is retargetted to it.
+  if (forDocumentNavigation && nsContentUtils::IsChromeDoc(doc)) {
+    nsAutoString retarget;
+
+    if (rootElement->GetAttr(kNameSpaceID_None,
+                             nsGkAtoms::retargetdocumentfocus, retarget)) {
+      nsIContent* retargetElement = doc->GetElementById(retarget);
+      // The common case here is the urlbar where focus is on the anonymous
+      // input inside the textbox, but the retargetdocumentfocus attribute
+      // refers to the textbox. The Contains check will return false and the
+      // IsInclusiveDescendantOf check will return true in this case.
+      if (retargetElement &&
+          (retargetElement == startContent ||
+           (!retargetElement->Contains(startContent) &&
+            startContent->IsInclusiveDescendantOf(retargetElement)))) {
+        startContent = rootElement;
+      }
+    }
+  }
+
+  NS_ASSERTION(startContent, "starting content not set");
+
+  // keep a reference to the starting content. If we find that again, it means
+  // we've iterated around completely and we don't want to adjust the focus.
+  // The skipOriginalContentCheck will be set to true only for the first time
+  // GetNextTabbableContent is called. This ensures that we don't break out
+  // when nothing is focused to start with. Specifically,
+  // GetNextTabbableContent first checks the root content -- which happens to
+  // be the same as the start content -- when nothing is focused and tabbing
+  // forward. Without skipOriginalContentCheck set to true, we'd end up
+  // returning right away and focusing nothing. Luckily, GetNextTabbableContent
+  // will never wrap around on its own, and can only return the original
+  // content when it is called a second time or later.
+  bool skipOriginalContentCheck = true;
+  const nsCOMPtr<nsIContent> originalStartContent = startContent;
+
+  LOGCONTENTNAVIGATION("Focus Navigation Start Content %s", startContent.get());
+  LOGFOCUSNAVIGATION(("  Forward: %d Tabindex: %d Ignore: %d DocNav: %d",
+                      forward, tabIndex, ignoreTabIndex,
+                      forDocumentNavigation));
+
+  while (doc) {
+    if (doNavigation) {
+      nsCOMPtr<nsIContent> nextFocus;
+      // TODO: MOZ_KnownLive is reruired due to bug 1770680
+      nsresult rv = GetNextTabbableContent(
+          presShell, rootElement,
+          MOZ_KnownLive(skipOriginalContentCheck ? nullptr
+                                                 : originalStartContent.get()),
+          startContent, forward, tabIndex, ignoreTabIndex,
+          forDocumentNavigation, aNavigateByKey, getter_AddRefs(nextFocus));
+      NS_ENSURE_SUCCESS(rv, rv);
+      if (rv == NS_SUCCESS_DOM_NO_OPERATION) {
+        // Navigation was redirected to a child process, so just return.
+        return NS_OK;
+      }
+
+      // found a content node to focus.
+      if (nextFocus) {
+        LOGCONTENTNAVIGATION("Next Content: %s", nextFocus.get());
+
+        // as long as the found node was not the same as the starting node,
+        // set it as the return value. For document navigation, we can return
+        // the same element in case there is only one content node that could
+        // be returned, for example, in a child process document.
+        if (nextFocus != originalStartContent || forDocumentNavigation) {
+          nextFocus.forget(aNextContent);
+        }
+        return NS_OK;
+      }
+
+      if (popupFrame && !forDocumentNavigation) {
+        // in a popup, so start again from the beginning of the popup. However,
+        // if we already started at the beginning, then there isn't anything to
+        // focus, so just return
+        if (startContent != rootElement) {
+          startContent = rootElement;
+          tabIndex = forward ? 1 : 0;
+          continue;
+        }
+        return NS_OK;
+      }
+    }
+
+    doNavigation = true;
+    skipOriginalContentCheck = forDocumentNavigation;
+    ignoreTabIndex = false;
+
+    if (aNoParentTraversal) {
+      if (startContent == rootElement) {
+        return NS_OK;
+      }
+
+      startContent = rootElement;
+      tabIndex = forward ? 1 : 0;
+      continue;
+    }
+
+    // Reached the beginning or end of the document. Next, navigate up to the
+    // parent document and try again.
+    nsCOMPtr<nsPIDOMWindowOuter> piWindow = doc->GetWindow();
+    NS_ENSURE_TRUE(piWindow, NS_ERROR_FAILURE);
+
+    nsCOMPtr<nsIDocShell> docShell = piWindow->GetDocShell();
+    NS_ENSURE_TRUE(docShell, NS_ERROR_FAILURE);
+
+    // Get the frame element this window is inside and, from that, get the
+    // parent document and presshell. If there is no enclosing frame element,
+    // then this is a top-level, embedded or remote window.
+    startContent = piWindow->GetFrameElementInternal();
+    if (startContent) {
+      doc = startContent->GetComposedDoc();
+      NS_ENSURE_TRUE(doc, NS_ERROR_FAILURE);
+
+      rootElement = doc->GetRootElement();
+      presShell = doc->GetPresShell();
+
+      // We can focus the root element now that we have moved to another
+      // document.
+      mayFocusRoot = true;
+
+      nsIFrame* frame = startContent->GetPrimaryFrame();
+      if (!frame) {
+        return NS_OK;
+      }
+
+      tabIndex = frame->IsFocusable().mTabIndex;
+      if (tabIndex < 0) {
+        tabIndex = 1;
+        ignoreTabIndex = true;
+      }
+
+      // if the frame is inside a popup, make sure to scan only within the
+      // popup. This handles the situation of tabbing amongst elements
+      // inside an iframe which is itself inside a popup. Otherwise,
+      // navigation would move outside the popup when tabbing outside the
+      // iframe.
+      if (!forDocumentNavigation) {
+        popupFrame = nsLayoutUtils::GetClosestFrameOfType(
+            frame, LayoutFrameType::MenuPopup);
+        if (popupFrame) {
+          rootElement = popupFrame->GetContent()->AsElement();
+          NS_ASSERTION(rootElement, "Popup frame doesn't have a content node");
+        }
+      }
+    } else {
+      if (aNavigateByKey) {
+        // There is no parent, so call the tree owner. This will tell the
+        // embedder or parent process that it should take the focus.
+        bool tookFocus;
+        docShell->TabToTreeOwner(forward, forDocumentNavigation, &tookFocus);
+        // If the tree owner took the focus, blur the current element.
+        if (tookFocus) {
+          RefPtr<BrowsingContext> focusedBC = GetFocusedBrowsingContext();
+          if (focusedBC && focusedBC->IsInProcess()) {
+            Blur(focusedBC, nullptr, true, true, false,
+                 GenerateFocusActionId());
+          } else {
+            nsCOMPtr<nsPIDOMWindowOuter> window = docShell->GetWindow();
+            window->SetFocusedElement(nullptr);
+          }
+          return NS_OK;
+        }
+      }
+
+      // If we have reached the end of the top-level document, focus the
+      // first element in the top-level document. This should always happen
+      // when navigating by document forwards but when navigating backwards,
+      // only do this if we started in another document or within a popup frame.
+      // If the focus started in this window outside a popup however, we should
+      // continue by looping around to the end again.
+      if (forDocumentNavigation && (forward || mayFocusRoot || popupFrame)) {
+        // HTML content documents can have their root element focused (a focus
+        // ring appears around the entire content area frame). This root
+        // appears in the tab order before all of the elements in the document.
+        // Chrome documents however cannot be focused directly, so instead we
+        // focus the first focusable element within the window.
+        // For example, the urlbar.
+        RefPtr<Element> rootElementForFocus =
+            GetRootForFocus(piWindow, doc, true, true);
+        return FocusFirst(rootElementForFocus, aNextContent);
+      }
+
+      // Once we have hit the top-level and have iterated to the end again, we
+      // just want to break out next time we hit this spot to prevent infinite
+      // iteration.
+      mayFocusRoot = true;
+
+      // reset the tab index and start again from the beginning or end
+      startContent = rootElement;
+      tabIndex = forward ? 1 : 0;
+    }
+
+    // wrapped all the way around and didn't find anything to move the focus
+    // to, so just break out
+    if (startContent == originalStartContent) {
+      break;
+    }
+  }
+
+  return NS_OK;
+}
+
+uint32_t nsFocusManager::ProgrammaticFocusFlags(const FocusOptions& aOptions) {
+  uint32_t flags = FLAG_BYJS;
+  if (aOptions.mPreventScroll) {
+    flags |= FLAG_NOSCROLL;
+  }
+  if (aOptions.mFocusVisible.WasPassed()) {
+    flags |= aOptions.mFocusVisible.Value() ? FLAG_SHOWRING : FLAG_NOSHOWRING;
+  }
+  if (UserActivation::IsHandlingKeyboardInput()) {
+    flags |= FLAG_BYKEY;
+  }
+  // TODO: We could do a similar thing if we're handling mouse input, but that
+  // changes focusability of some elements so may be more risky.
+  return flags;
+}
+
+static bool IsHostOrSlot(const nsIContent* aContent) {
+  return aContent && (aContent->GetShadowRoot() ||
+                      aContent->IsHTMLElement(nsGkAtoms::slot));
+}
+
+// Helper class to iterate contents in scope by traversing flattened tree
+// in tree order
+class MOZ_STACK_CLASS ScopedContentTraversal {
+ public:
+  ScopedContentTraversal(nsIContent* aStartContent, nsIContent* aOwner)
+      : mCurrent(aStartContent), mOwner(aOwner) {
+    MOZ_ASSERT(aStartContent);
+  }
+
+  void Next();
+  void Prev();
+
+  void Reset() { SetCurrent(mOwner); }
+
+  nsIContent* GetCurrent() const { return mCurrent; }
+
+ private:
+  void SetCurrent(nsIContent* aContent) { mCurrent = aContent; }
+
+  nsIContent* mCurrent;
+  nsIContent* mOwner;
+};
+
+void ScopedContentTraversal::Next() {
+  MOZ_ASSERT(mCurrent);
+
+  // Get mCurrent's first child if it's in the same scope.
+  if (!IsHostOrSlot(mCurrent) || mCurrent == mOwner) {
+    StyleChildrenIterator iter(mCurrent);
+    nsIContent* child = iter.GetNextChild();
+    if (child) {
+      SetCurrent(child);
+      return;
+    }
+  }
+
+  // If mOwner has no children, END traversal
+  if (mCurrent == mOwner) {
+    SetCurrent(nullptr);
+    return;
+  }
+
+  nsIContent* current = mCurrent;
+  while (1) {
+    // Create parent's iterator and move to current
+    nsIContent* parent = current->GetFlattenedTreeParent();
+    StyleChildrenIterator parentIter(parent);
+    parentIter.Seek(current);
+
+    // Get next sibling of current
+    if (nsIContent* next = parentIter.GetNextChild()) {
+      SetCurrent(next);
+      return;
+    }
+
+    // If no next sibling and parent is mOwner, END traversal
+    if (parent == mOwner) {
+      SetCurrent(nullptr);
+      return;
+    }
+
+    current = parent;
+  }
+}
+
+void ScopedContentTraversal::Prev() {
+  MOZ_ASSERT(mCurrent);
+
+  nsIContent* parent;
+  nsIContent* last;
+  if (mCurrent == mOwner) {
+    // Get last child of mOwner
+    StyleChildrenIterator ownerIter(mOwner, false /* aStartAtBeginning */);
+    last = ownerIter.GetPreviousChild();
+
+    parent = last;
+  } else {
+    // Create parent's iterator and move to mCurrent
+    parent = mCurrent->GetFlattenedTreeParent();
+    StyleChildrenIterator parentIter(parent);
+    parentIter.Seek(mCurrent);
+
+    // Get previous sibling
+    last = parentIter.GetPreviousChild();
+  }
+
+  while (last) {
+    parent = last;
+    if (IsHostOrSlot(parent)) {
+      // Skip contents in other scopes
+      break;
+    }
+
+    // Find last child
+    StyleChildrenIterator iter(parent, false /* aStartAtBeginning */);
+    last = iter.GetPreviousChild();
+  }
+
+  // If parent is mOwner and no previous sibling remains, END traversal
+  SetCurrent(parent == mOwner ? nullptr : parent);
+}
+
+/**
+ * Returns scope owner of aContent.
+ * A scope owner is either a shadow host, or slot.
+ */
+static nsIContent* FindScopeOwner(nsIContent* aContent) {
+  nsIContent* currentContent = aContent;
+  while (currentContent) {
+    nsIContent* parent = currentContent->GetFlattenedTreeParent();
+
+    // Shadow host / Slot
+    if (IsHostOrSlot(parent)) {
+      return parent;
+    }
+
+    currentContent = parent;
+  }
+
+  return nullptr;
+}
+
+/**
+ * Host and Slot elements need to be handled as if they had tabindex 0 even
+ * when they don't have the attribute. This is a helper method to get the
+ * right value for focus navigation. If aIsFocusable is passed, it is set to
+ * true if the element itself is focusable.
+ */
+static int32_t HostOrSlotTabIndexValue(const nsIContent* aContent,
+                                       bool* aIsFocusable = nullptr) {
+  MOZ_ASSERT(IsHostOrSlot(aContent));
+
+  if (aIsFocusable) {
+    nsIFrame* frame = aContent->GetPrimaryFrame();
+    *aIsFocusable = frame && frame->IsFocusable().mTabIndex >= 0;
+  }
+
+  const nsAttrValue* attrVal =
+      aContent->AsElement()->GetParsedAttr(nsGkAtoms::tabindex);
+  if (!attrVal) {
+    return 0;
+  }
+
+  if (attrVal->Type() == nsAttrValue::eInteger) {
+    return attrVal->GetIntegerValue();
+  }
+
+  return -1;
+}
+
+nsIContent* nsFocusManager::GetNextTabbableContentInScope(
+    nsIContent* aOwner, nsIContent* aStartContent,
+    nsIContent* aOriginalStartContent, bool aForward, int32_t aCurrentTabIndex,
+    bool aIgnoreTabIndex, bool aForDocumentNavigation, bool aNavigateByKey,
+    bool aSkipOwner) {
+  MOZ_ASSERT(IsHostOrSlot(aOwner), "Scope owner should be host or slot");
+
+  // XXX: Why don't we ignore tabindex when the current tabindex < 0?
+  MOZ_ASSERT_IF(aCurrentTabIndex < 0, aIgnoreTabIndex);
+
+  if (!aSkipOwner && (aForward && aOwner == aStartContent)) {
+    if (nsIFrame* frame = aOwner->GetPrimaryFrame()) {
+      auto focusable = frame->IsFocusable();
+      if (focusable && focusable.mTabIndex >= 0) {
+        return aOwner;
+      }
+    }
+  }
+
+  //
+  // Iterate contents in scope
+  //
+  ScopedContentTraversal contentTraversal(aStartContent, aOwner);
+  nsCOMPtr<nsIContent> iterContent;
+  nsIContent* firstNonChromeOnly =
+      aStartContent->IsInNativeAnonymousSubtree()
+          ? aStartContent->FindFirstNonChromeOnlyAccessContent()
+          : nullptr;
+  while (1) {
+    // Iterate tab index to find corresponding contents in scope
+
+    while (1) {
+      // Iterate remaining contents in scope to find next content to focus
+
+      // Get next content
+      aForward ? contentTraversal.Next() : contentTraversal.Prev();
+      iterContent = contentTraversal.GetCurrent();
+
+      if (firstNonChromeOnly && firstNonChromeOnly == iterContent) {
+        // We just broke out from the native anonymous content, so move
+        // to the previous/next node of the native anonymous owner.
+        if (aForward) {
+          contentTraversal.Next();
+        } else {
+          contentTraversal.Prev();
+        }
+        iterContent = contentTraversal.GetCurrent();
+      }
+      if (!iterContent) {
+        // Reach the end
+        break;
+      }
+
+      int32_t tabIndex = 0;
+      if (iterContent->IsInNativeAnonymousSubtree() &&
+          iterContent->GetPrimaryFrame()) {
+        tabIndex = iterContent->GetPrimaryFrame()->IsFocusable().mTabIndex;
+      } else if (IsHostOrSlot(iterContent)) {
+        tabIndex = HostOrSlotTabIndexValue(iterContent);
+      } else {
+        nsIFrame* frame = iterContent->GetPrimaryFrame();
+        if (!frame) {
+          continue;
+        }
+        tabIndex = frame->IsFocusable().mTabIndex;
+      }
+      if (tabIndex < 0 || !(aIgnoreTabIndex || tabIndex == aCurrentTabIndex)) {
+        continue;
+      }
+
+      if (!IsHostOrSlot(iterContent)) {
+        nsCOMPtr<nsIContent> elementInFrame;
+        bool checkSubDocument = true;
+        if (aForDocumentNavigation &&
+            TryDocumentNavigation(iterContent, &checkSubDocument,
+                                  getter_AddRefs(elementInFrame))) {
+          return elementInFrame;
+        }
+        if (!checkSubDocument) {
+          continue;
+        }
+
+        if (TryToMoveFocusToSubDocument(iterContent, aOriginalStartContent,
+                                        aForward, aForDocumentNavigation,
+                                        aNavigateByKey,
+                                        getter_AddRefs(elementInFrame))) {
+          return elementInFrame;
+        }
+
+        // Found content to focus
+        return iterContent;
+      }
+
+      // Search in scope owned by iterContent
+      nsIContent* contentToFocus = GetNextTabbableContentInScope(
+          iterContent, iterContent, aOriginalStartContent, aForward,
+          aForward ? 1 : 0, aIgnoreTabIndex, aForDocumentNavigation,
+          aNavigateByKey, false /* aSkipOwner */);
+      if (contentToFocus) {
+        return contentToFocus;
+      }
+    };
+
+    // If already at lowest priority tab (0), end search completely.
+    // A bit counterintuitive but true, tabindex order goes 1, 2, ... 32767, 0
+    if (aCurrentTabIndex == (aForward ? 0 : 1)) {
+      break;
+    }
+
+    // We've been just trying to find some focusable element, and haven't, so
+    // bail out.
+    if (aIgnoreTabIndex) {
+      break;
+    }
+
+    // Continue looking for next highest priority tabindex
+    aCurrentTabIndex = GetNextTabIndex(aOwner, aCurrentTabIndex, aForward);
+    contentTraversal.Reset();
+  }
+
+  // Return scope owner at last for backward navigation if its tabindex
+  // is non-negative
+  if (!aSkipOwner && !aForward) {
+    if (nsIFrame* frame = aOwner->GetPrimaryFrame()) {
+      auto focusable = frame->IsFocusable();
+      if (focusable && focusable.mTabIndex >= 0) {
+        return aOwner;
+      }
+    }
+  }
+
+  return nullptr;
+}
+
+nsIContent* nsFocusManager::GetNextTabbableContentInAncestorScopes(
+    nsIContent* aStartOwner, nsCOMPtr<nsIContent>& aStartContent /* inout */,
+    nsIContent* aOriginalStartContent, bool aForward, int32_t* aCurrentTabIndex,
+    bool* aIgnoreTabIndex, bool aForDocumentNavigation, bool aNavigateByKey) {
+  MOZ_ASSERT(aStartOwner == FindScopeOwner(aStartContent),
+             "aStartOWner should be the scope owner of aStartContent");
+  MOZ_ASSERT(IsHostOrSlot(aStartOwner), "scope owner should be host or slot");
+
+  nsCOMPtr<nsIContent> owner = aStartOwner;
+  nsCOMPtr<nsIContent> startContent = aStartContent;
+  while (IsHostOrSlot(owner)) {
+    int32_t tabIndex = 0;
+    if (IsHostOrSlot(startContent)) {
+      tabIndex = HostOrSlotTabIndexValue(startContent);
+    } else if (nsIFrame* frame = startContent->GetPrimaryFrame()) {
+      tabIndex = frame->IsFocusable().mTabIndex;
+    } else {
+      startContent->IsFocusable(&tabIndex);
+    }
+    nsIContent* contentToFocus = GetNextTabbableContentInScope(
+        owner, startContent, aOriginalStartContent, aForward, tabIndex,
+        tabIndex < 0, aForDocumentNavigation, aNavigateByKey,
+        false /* aSkipOwner */);
+    if (contentToFocus) {
+      return contentToFocus;
+    }
+
+    startContent = owner;
+    owner = FindScopeOwner(startContent);
+  }
+
+  // If not found in shadow DOM, search from the top level shadow host in light
+  // DOM
+  aStartContent = startContent;
+  *aCurrentTabIndex = HostOrSlotTabIndexValue(startContent);
+
+  if (*aCurrentTabIndex < 0) {
+    *aIgnoreTabIndex = true;
+  }
+
+  return nullptr;
+}
+
+static nsIContent* GetTopLevelScopeOwner(nsIContent* aContent) {
+  nsIContent* topLevelScopeOwner = nullptr;
+  while (aContent) {
+    if (HTMLSlotElement* slot = aContent->GetAssignedSlot()) {
+      aContent = slot;
+      topLevelScopeOwner = aContent;
+    } else if (ShadowRoot* shadowRoot = aContent->GetContainingShadow()) {
+      aContent = shadowRoot->Host();
+      topLevelScopeOwner = aContent;
+    } else {
+      aContent = aContent->GetParent();
+      if (aContent && HTMLSlotElement::FromNode(aContent)) {
+        topLevelScopeOwner = aContent;
+      }
+    }
+  }
+
+  return topLevelScopeOwner;
+}
+
+nsresult nsFocusManager::GetNextTabbableContent(
+    PresShell* aPresShell, nsIContent* aRootContent,
+    nsIContent* aOriginalStartContent, nsIContent* aStartContent, bool aForward,
+    int32_t aCurrentTabIndex, bool aIgnoreTabIndex, bool aForDocumentNavigation,
+    bool aNavigateByKey, nsIContent** aResultContent) {
+  *aResultContent = nullptr;
+
+  if (!aStartContent) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIContent> startContent = aStartContent;
+  nsCOMPtr<nsIContent> currentTopLevelScopeOwner =
+      GetTopLevelScopeOwner(startContent);
+
+  LOGCONTENTNAVIGATION("GetNextTabbable: %s", startContent);
+  LOGFOCUSNAVIGATION(("  tabindex: %d", aCurrentTabIndex));
+
+  // If startContent is a shadow host or slot in forward navigation,
+  // search in scope owned by startContent
+  if (aForward && IsHostOrSlot(startContent)) {
+    nsIContent* contentToFocus = GetNextTabbableContentInScope(
+        startContent, startContent, aOriginalStartContent, aForward,
+        aForward ? 1 : 0, aIgnoreTabIndex, aForDocumentNavigation,
+        aNavigateByKey, true /* aSkipOwner */);
+    if (contentToFocus) {
+      NS_ADDREF(*aResultContent = contentToFocus);
+      return NS_OK;
+    }
+  }
+
+  // If startContent is in a scope owned by Shadow DOM search from scope
+  // including startContent
+  if (nsCOMPtr<nsIContent> owner = FindScopeOwner(startContent)) {
+    nsIContent* contentToFocus = GetNextTabbableContentInAncestorScopes(
+        owner, startContent /* inout */, aOriginalStartContent, aForward,
+        &aCurrentTabIndex, &aIgnoreTabIndex, aForDocumentNavigation,
+        aNavigateByKey);
+    if (contentToFocus) {
+      NS_ADDREF(*aResultContent = contentToFocus);
+      return NS_OK;
+    }
+  }
+
+  // If we reach here, it means no next tabbable content in shadow DOM.
+  // We need to continue searching in light DOM, starting at the top level
+  // shadow host in light DOM (updated startContent) and its tabindex
+  // (updated aCurrentTabIndex).
+  MOZ_ASSERT(!FindScopeOwner(startContent),
+             "startContent should not be owned by Shadow DOM at this point");
+
+  nsPresContext* presContext = aPresShell->GetPresContext();
+
+  bool getNextFrame = true;
+  nsCOMPtr<nsIContent> iterStartContent = startContent;
+  nsIContent* topLevelScopeStartContent = startContent;
+  // Iterate tab index to find corresponding contents
+  while (1) {
+    nsIFrame* frame = iterStartContent->GetPrimaryFrame();
+    // if there is no frame, look for another content node that has a frame
+    while (!frame) {
+      // if the root content doesn't have a frame, just return
+      if (iterStartContent == aRootContent) {
+        return NS_OK;
+      }
+
+      // look for the next or previous content node in tree order
+      iterStartContent = aForward ? iterStartContent->GetNextNode()
+                                  : iterStartContent->GetPreviousContent();
+      if (!iterStartContent) {
+        break;
+      }
+
+      frame = iterStartContent->GetPrimaryFrame();
+      // Host without frame, enter its scope.
+      if (!frame && iterStartContent->GetShadowRoot()) {
+        int32_t tabIndex = HostOrSlotTabIndexValue(iterStartContent);
+        if (tabIndex >= 0 &&
+            (aIgnoreTabIndex || aCurrentTabIndex == tabIndex)) {
+          nsIContent* contentToFocus = GetNextTabbableContentInScope(
+              iterStartContent, iterStartContent, aOriginalStartContent,
+              aForward, aForward ? 1 : 0, aIgnoreTabIndex,
+              aForDocumentNavigation, aNavigateByKey, true /* aSkipOwner */);
+          if (contentToFocus) {
+            NS_ADDREF(*aResultContent = contentToFocus);
+            return NS_OK;
+          }
+        }
+      }
+      // we've already skipped over the initial focused content, so we
+      // don't want to traverse frames.
+      getNextFrame = false;
+    }
+
+    nsCOMPtr<nsIFrameEnumerator> frameTraversal;
+    if (frame) {
+      // For tab navigation, pass false for aSkipPopupChecks so that we don't
+      // iterate into or out of a popup. For document naviation pass true to
+      // ignore these boundaries.
+      nsresult rv = NS_NewFrameTraversal(
+          getter_AddRefs(frameTraversal), presContext, frame, ePreOrder,
+          false,                  // aVisual
+          false,                  // aLockInScrollView
+          true,                   // aFollowOOFs
+          aForDocumentNavigation  // aSkipPopupChecks
+      );
+      NS_ENSURE_SUCCESS(rv, rv);
+
+      if (iterStartContent == aRootContent) {
+        if (!aForward) {
+          frameTraversal->Last();
+        } else if (aRootContent->IsFocusable()) {
+          frameTraversal->Next();
+        }
+        frame = frameTraversal->CurrentItem();
+      } else if (getNextFrame &&
+                 (!iterStartContent ||
+                  !iterStartContent->IsHTMLElement(nsGkAtoms::area))) {
+        // Need to do special check in case we're in an imagemap which has
+        // multiple content nodes per frame, so don't skip over the starting
+        // frame.
+        frame = frameTraversal->Traverse(aForward);
+      }
+    }
+
+    nsIContent* oldTopLevelScopeOwner = nullptr;
+    // Walk frames to find something tabbable matching aCurrentTabIndex
+    while (frame) {
+      // Try to find the topmost scope owner, since we want to skip the node
+      // that is not owned by document in frame traversal.
+      const nsCOMPtr<nsIContent> currentContent = frame->GetContent();
+      if (currentTopLevelScopeOwner) {
+        oldTopLevelScopeOwner = currentTopLevelScopeOwner;
+      }
+      currentTopLevelScopeOwner = GetTopLevelScopeOwner(currentContent);
+      if (currentTopLevelScopeOwner &&
+          currentTopLevelScopeOwner == oldTopLevelScopeOwner) {
+        // We're within non-document scope, continue.
+        do {
+          if (aForward) {
+            frameTraversal->Next();
+          } else {
+            frameTraversal->Prev();
+          }
+          frame = static_cast<nsIFrame*>(frameTraversal->CurrentItem());
+          // For the usage of GetPrevContinuation, see the comment
+          // at the end of while (frame) loop.
+        } while (frame && frame->GetPrevContinuation());
+        continue;
+      }
+
+      // For document navigation, check if this element is an open panel. Since
+      // panels aren't focusable (tabIndex would be -1), we'll just assume that
+      // for document navigation, the tabIndex is 0.
+      if (aForDocumentNavigation && currentContent && (aCurrentTabIndex == 0) &&
+          currentContent->IsXULElement(nsGkAtoms::panel)) {
+        nsMenuPopupFrame* popupFrame = do_QueryFrame(frame);
+        // Check if the panel is open. Closed panels are ignored since you can't
+        // focus anything in them.
+        if (popupFrame && popupFrame->IsOpen()) {
+          // When moving backward, skip the popup we started in otherwise it
+          // will be selected again.
+          bool validPopup = true;
+          if (!aForward) {
+            nsIContent* content = topLevelScopeStartContent;
+            while (content) {
+              if (content == currentContent) {
+                validPopup = false;
+                break;
+              }
+
+              content = content->GetParent();
+            }
+          }
+
+          if (validPopup) {
+            // Since a panel isn't focusable itself, find the first focusable
+            // content within the popup. If there isn't any focusable content
+            // in the popup, skip this popup and continue iterating through the
+            // frames. We pass the panel itself (currentContent) as the starting
+            // and root content, so that we only find content within the panel.
+            // Note also that we pass false for aForDocumentNavigation since we
+            // want to locate the first content, not the first document.
+            nsresult rv = GetNextTabbableContent(
+                aPresShell, currentContent, nullptr, currentContent, true, 1,
+                false, false, aNavigateByKey, aResultContent);
+            if (NS_SUCCEEDED(rv) && *aResultContent) {
+              return rv;
+            }
+          }
+        }
+      }
+
+      // As of now, 2018/04/12, sequential focus navigation is still
+      // in the obsolete Shadow DOM specification.
+      // http://w3c.github.io/webcomponents/spec/shadow/#sequential-focus-navigation
+      // "if ELEMENT is focusable, a shadow host, or a slot element,
+      //  append ELEMENT to NAVIGATION-ORDER."
+      // and later in "For each element ELEMENT in NAVIGATION-ORDER: "
+      // hosts and slots are handled before other elements.
+      if (currentTopLevelScopeOwner) {
+        bool focusableHostSlot;
+        int32_t tabIndex = HostOrSlotTabIndexValue(currentTopLevelScopeOwner,
+                                                   &focusableHostSlot);
+        // Host or slot itself isn't focusable or going backwards, enter its
+        // scope.
+        if ((!aForward || !focusableHostSlot) && tabIndex >= 0 &&
+            (aIgnoreTabIndex || aCurrentTabIndex == tabIndex)) {
+          nsIContent* contentToFocus = GetNextTabbableContentInScope(
+              currentTopLevelScopeOwner, currentTopLevelScopeOwner,
+              aOriginalStartContent, aForward, aForward ? 1 : 0,
+              aIgnoreTabIndex, aForDocumentNavigation, aNavigateByKey,
+              true /* aSkipOwner */);
+          if (contentToFocus) {
+            NS_ADDREF(*aResultContent = contentToFocus);
+            return NS_OK;
+          }
+          // If we've wrapped around already, then carry on.
+          if (aOriginalStartContent &&
+              currentTopLevelScopeOwner ==
+                  GetTopLevelScopeOwner(aOriginalStartContent)) {
+            // FIXME: Shouldn't this return null instead?  aOriginalStartContent
+            // isn't focusable after all.
+            NS_ADDREF(*aResultContent = aOriginalStartContent);
+            return NS_OK;
+          }
+        }
+        // There is no next tabbable content in currentTopLevelScopeOwner's
+        // scope. We should continue the loop in order to skip all contents that
+        // is in currentTopLevelScopeOwner's scope.
+        continue;
+      }
+
+      MOZ_ASSERT(!GetTopLevelScopeOwner(currentContent),
+                 "currentContent should be in top-level-scope at this point");
+
+      // TabIndex not set defaults to 0 for form elements, anchors and other
+      // elements that are normally focusable. Tabindex defaults to -1
+      // for elements that are not normally focusable.
+      // The returned computed tabindex from IsFocusable() is as follows:
+      // clang-format off
+      //          < 0 not tabbable at all
+      //          == 0 in normal tab order (last after positive tabindexed items)
+      //          > 0 can be tabbed to in the order specified by this value
+      // clang-format on
+      int32_t tabIndex = frame->IsFocusable().mTabIndex;
+
+      LOGCONTENTNAVIGATION("Next Tabbable %s:", frame->GetContent());
+      LOGFOCUSNAVIGATION(
+          ("  with tabindex: %d expected: %d", tabIndex, aCurrentTabIndex));
+
+      if (tabIndex >= 0) {
+        NS_ASSERTION(currentContent,
+                     "IsFocusable set a tabindex for a frame with no content");
+        if (!aForDocumentNavigation &&
+            currentContent->IsHTMLElement(nsGkAtoms::img) &&
+            currentContent->AsElement()->HasAttr(kNameSpaceID_None,
+                                                 nsGkAtoms::usemap)) {
+          // This is an image with a map. Image map areas are not traversed by
+          // nsIFrameTraversal so look for the next or previous area element.
+          nsIContent* areaContent = GetNextTabbableMapArea(
+              aForward, aCurrentTabIndex, currentContent->AsElement(),
+              iterStartContent);
+          if (areaContent) {
+            NS_ADDREF(*aResultContent = areaContent);
+            return NS_OK;
+          }
+        } else if (aIgnoreTabIndex || aCurrentTabIndex == tabIndex) {
+          // break out if we've wrapped around to the start again.
+          if (aOriginalStartContent &&
+              currentContent == aOriginalStartContent) {
+            NS_ADDREF(*aResultContent = currentContent);
+            return NS_OK;
+          }
+
+          // If this is a remote child browser, call NavigateDocument to have
+          // the child process continue the navigation. Return a special error
+          // code to have the caller return early. If the child ends up not
+          // being focusable in some way, the child process will call back
+          // into document navigation again by calling MoveFocus.
+          if (BrowserParent* remote = BrowserParent::GetFrom(currentContent)) {
+            if (aNavigateByKey) {
+              remote->NavigateByKey(aForward, aForDocumentNavigation);
+              return NS_SUCCESS_DOM_NO_OPERATION;
+            }
+            return NS_OK;
+          }
+
+          // Same as above but for out-of-process iframes
+          if (auto* bbc = BrowserBridgeChild::GetFrom(currentContent)) {
+            if (aNavigateByKey) {
+              bbc->NavigateByKey(aForward, aForDocumentNavigation);
+              return NS_SUCCESS_DOM_NO_OPERATION;
+            }
+            return NS_OK;
+          }
+
+          // Next, for document navigation, check if this a non-remote child
+          // document.
+          bool checkSubDocument = true;
+          if (aForDocumentNavigation &&
+              TryDocumentNavigation(currentContent, &checkSubDocument,
+                                    aResultContent)) {
+            return NS_OK;
+          }
+
+          if (checkSubDocument) {
+            // found a node with a matching tab index. Check if it is a child
+            // frame. If so, navigate into the child frame instead.
+            if (TryToMoveFocusToSubDocument(
+                    currentContent, aOriginalStartContent, aForward,
+                    aForDocumentNavigation, aNavigateByKey, aResultContent)) {
+              MOZ_ASSERT(*aResultContent);
+              return NS_OK;
+            }
+            // otherwise, use this as the next content node to tab to, unless
+            // this was the element we started on. This would happen for
+            // instance on an element with child frames, where frame navigation
+            // could return the original element again. In that case, just skip
+            // it. Also, if the next content node is the root content, then
+            // return it. This latter case would happen only if someone made a
+            // popup focusable.
+            else if (currentContent == aRootContent ||
+                     currentContent != startContent) {
+              NS_ADDREF(*aResultContent = currentContent);
+              return NS_OK;
+            }
+          }
+        }
+      } else if (aOriginalStartContent &&
+                 currentContent == aOriginalStartContent) {
+        // not focusable, so return if we have wrapped around to the original
+        // content. This is necessary in case the original starting content was
+        // not focusable.
+        //
+        // FIXME: Shouldn't this return null instead? currentContent isn't
+        // focusable after all.
+        NS_ADDREF(*aResultContent = currentContent);
+        return NS_OK;
+      }
+
+      // Move to the next or previous frame, but ignore continuation frames
+      // since only the first frame should be involved in focusability.
+      // Otherwise, a loop will occur in the following example:
+      //   <span tabindex="1">...<a/><a/>...</span>
+      // where the text wraps onto multiple lines. Tabbing from the second
+      // link can find one of the span's continuation frames between the link
+      // and the end of the span, and the span would end up getting focused
+      // again.
+      do {
+        if (aForward) {
+          frameTraversal->Next();
+        } else {
+          frameTraversal->Prev();
+        }
+        frame = static_cast<nsIFrame*>(frameTraversal->CurrentItem());
+      } while (frame && frame->GetPrevContinuation());
+    }
+
+    // If already at lowest priority tab (0), end search completely.
+    // A bit counterintuitive but true, tabindex order goes 1, 2, ... 32767, 0
+    if (aCurrentTabIndex == (aForward ? 0 : 1)) {
+      // if going backwards, the canvas should be focused once the beginning
+      // has been reached, so get the root element.
+      if (!aForward) {
+        nsCOMPtr<nsPIDOMWindowOuter> window = GetCurrentWindow(aRootContent);
+        NS_ENSURE_TRUE(window, NS_ERROR_FAILURE);
+
+        RefPtr<Element> docRoot = GetRootForFocus(
+            window, aRootContent->GetComposedDoc(), false, true);
+        FocusFirst(docRoot, aResultContent);
+      }
+      break;
+    }
+
+    // continue looking for next highest priority tabindex
+    aCurrentTabIndex =
+        GetNextTabIndex(aRootContent, aCurrentTabIndex, aForward);
+    startContent = iterStartContent = aRootContent;
+    currentTopLevelScopeOwner = GetTopLevelScopeOwner(startContent);
+  }
+
+  return NS_OK;
+}
+
+bool nsFocusManager::TryDocumentNavigation(nsIContent* aCurrentContent,
+                                           bool* aCheckSubDocument,
+                                           nsIContent** aResultContent) {
+  *aCheckSubDocument = true;
+  if (RefPtr<Element> rootElementForChildDocument =
+          GetRootForChildDocument(aCurrentContent)) {
+    // If GetRootForChildDocument returned something then call
+    // FocusFirst to find the root or first element to focus within
+    // the child document. If this is a frameset though, skip this and
+    // fall through to normal tab navigation to iterate into
+    // the frameset's frames and locate the first focusable frame.
+    if (!rootElementForChildDocument->IsHTMLElement(nsGkAtoms::frameset)) {
+      *aCheckSubDocument = false;
+      Unused << FocusFirst(rootElementForChildDocument, aResultContent);
+      return *aResultContent != nullptr;
+    }
+  } else {
+    // Set aCheckSubDocument to false, as this was neither a frame
+    // type element or a child document that was focusable.
+    *aCheckSubDocument = false;
+  }
+
+  return false;
+}
+
+bool nsFocusManager::TryToMoveFocusToSubDocument(
+    nsIContent* aCurrentContent, nsIContent* aOriginalStartContent,
+    bool aForward, bool aForDocumentNavigation, bool aNavigateByKey,
+    nsIContent** aResultContent) {
+  Document* doc = aCurrentContent->GetComposedDoc();
+  NS_ASSERTION(doc, "content not in document");
+  Document* subdoc = doc->GetSubDocumentFor(aCurrentContent);
+  if (subdoc && !subdoc->EventHandlingSuppressed()) {
+    if (aForward) {
+      // When tabbing forward into a frame, return the root
+      // frame so that the canvas becomes focused.
+      if (nsCOMPtr<nsPIDOMWindowOuter> subframe = subdoc->GetWindow()) {
+        *aResultContent = GetRootForFocus(subframe, subdoc, false, true);
+        if (*aResultContent) {
+          NS_ADDREF(*aResultContent);
+          return true;
+        }
+      }
+    }
+    if (RefPtr<Element> rootElement = subdoc->GetRootElement()) {
+      if (RefPtr<PresShell> subPresShell = subdoc->GetPresShell()) {
+        nsresult rv = GetNextTabbableContent(
+            subPresShell, rootElement, aOriginalStartContent, rootElement,
+            aForward, (aForward ? 1 : 0), false, aForDocumentNavigation,
+            aNavigateByKey, aResultContent);
+        NS_ENSURE_SUCCESS(rv, false);
+        if (*aResultContent) {
+          return true;
+        }
+      }
+    }
+  }
+  return false;
+}
+
+nsIContent* nsFocusManager::GetNextTabbableMapArea(bool aForward,
+                                                   int32_t aCurrentTabIndex,
+                                                   Element* aImageContent,
+                                                   nsIContent* aStartContent) {
+  if (aImageContent->IsInComposedDoc()) {
+    HTMLImageElement* imgElement = HTMLImageElement::FromNode(aImageContent);
+    // The caller should check the element type, so we can assert here.
+    MOZ_ASSERT(imgElement);
+
+    nsCOMPtr<nsIContent> mapContent = imgElement->FindImageMap();
+    if (!mapContent) {
+      return nullptr;
+    }
+    // First see if the the start content is in this map
+    Maybe<uint32_t> indexOfStartContent =
+        mapContent->ComputeIndexOf(aStartContent);
+    int32_t tabIndex;
+    nsIContent* scanStartContent;
+    if (indexOfStartContent.isNothing() ||
+        (aStartContent->IsFocusable(&tabIndex) &&
+         tabIndex != aCurrentTabIndex)) {
+      // If aStartContent is in this map we must start iterating past it.
+      // We skip the case where aStartContent has tabindex == aStartContent
+      // since the next tab ordered element might be before it
+      // (or after for backwards) in the child list.
+      scanStartContent =
+          aForward ? mapContent->GetFirstChild() : mapContent->GetLastChild();
+    } else {
+      scanStartContent = aForward ? aStartContent->GetNextSibling()
+                                  : aStartContent->GetPreviousSibling();
+    }
+
+    for (nsCOMPtr<nsIContent> areaContent = scanStartContent; areaContent;
+         areaContent = aForward ? areaContent->GetNextSibling()
+                                : areaContent->GetPreviousSibling()) {
+      if (areaContent->IsFocusable(&tabIndex) && tabIndex == aCurrentTabIndex) {
+        return areaContent;
+      }
+    }
+  }
+
+  return nullptr;
+}
+
+int32_t nsFocusManager::GetNextTabIndex(nsIContent* aParent,
+                                        int32_t aCurrentTabIndex,
+                                        bool aForward) {
+  int32_t tabIndex, childTabIndex;
+  StyleChildrenIterator iter(aParent);
+
+  if (aForward) {
+    tabIndex = 0;
+    for (nsIContent* child = iter.GetNextChild(); child;
+         child = iter.GetNextChild()) {
+      // Skip child's descendants if child is a shadow host or slot, as they are
+      // in the focus navigation scope owned by child's shadow root
+      if (!IsHostOrSlot(child)) {
+        childTabIndex = GetNextTabIndex(child, aCurrentTabIndex, aForward);
+        if (childTabIndex > aCurrentTabIndex && childTabIndex != tabIndex) {
+          tabIndex = (tabIndex == 0 || childTabIndex < tabIndex) ? childTabIndex
+                                                                 : tabIndex;
+        }
+      }
+
+      nsAutoString tabIndexStr;
+      if (child->IsElement()) {
+        child->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::tabindex,
+                                    tabIndexStr);
+      }
+      nsresult ec;
+      int32_t val = tabIndexStr.ToInteger(&ec);
+      if (NS_SUCCEEDED(ec) && val > aCurrentTabIndex && val != tabIndex) {
+        tabIndex = (tabIndex == 0 || val < tabIndex) ? val : tabIndex;
+      }
+    }
+  } else { /* !aForward */
+    tabIndex = 1;
+    for (nsIContent* child = iter.GetNextChild(); child;
+         child = iter.GetNextChild()) {
+      // Skip child's descendants if child is a shadow host or slot, as they are
+      // in the focus navigation scope owned by child's shadow root
+      if (!IsHostOrSlot(child)) {
+        childTabIndex = GetNextTabIndex(child, aCurrentTabIndex, aForward);
+        if ((aCurrentTabIndex == 0 && childTabIndex > tabIndex) ||
+            (childTabIndex < aCurrentTabIndex && childTabIndex > tabIndex)) {
+          tabIndex = childTabIndex;
+        }
+      }
+
+      nsAutoString tabIndexStr;
+      if (child->IsElement()) {
+        child->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::tabindex,
+                                    tabIndexStr);
+      }
+      nsresult ec;
+      int32_t val = tabIndexStr.ToInteger(&ec);
+      if (NS_SUCCEEDED(ec)) {
+        if ((aCurrentTabIndex == 0 && val > tabIndex) ||
+            (val < aCurrentTabIndex && val > tabIndex)) {
+          tabIndex = val;
+        }
+      }
+    }
+  }
+
+  return tabIndex;
+}
+
+nsresult nsFocusManager::FocusFirst(Element* aRootElement,
+                                    nsIContent** aNextContent) {
+  if (!aRootElement) {
+    return NS_OK;
+  }
+
+  Document* doc = aRootElement->GetComposedDoc();
+  if (doc) {
+    if (nsContentUtils::IsChromeDoc(doc)) {
+      // If the redirectdocumentfocus attribute is set, redirect the focus to a
+      // specific element. This is primarily used to retarget the focus to the
+      // urlbar during document navigation.
+      nsAutoString retarget;
+
+      if (aRootElement->GetAttr(kNameSpaceID_None,
+                                nsGkAtoms::retargetdocumentfocus, retarget)) {
+        RefPtr<Element> element = doc->GetElementById(retarget);
+        nsCOMPtr<nsIContent> retargetElement =
+            FlushAndCheckIfFocusable(element, 0);
+        if (retargetElement) {
+          retargetElement.forget(aNextContent);
+          return NS_OK;
+        }
+      }
+    }
+
+    nsCOMPtr<nsIDocShell> docShell = doc->GetDocShell();
+    if (docShell->ItemType() == nsIDocShellTreeItem::typeChrome) {
+      // If the found content is in a chrome shell, navigate forward one
+      // tabbable item so that the first item is focused. Note that we
+      // always go forward and not back here.
+      if (RefPtr<PresShell> presShell = doc->GetPresShell()) {
+        return GetNextTabbableContent(presShell, aRootElement, nullptr,
+                                      aRootElement, true, 1, false, false, true,
+                                      aNextContent);
+      }
+    }
+  }
+
+  NS_ADDREF(*aNextContent = aRootElement);
+  return NS_OK;
+}
+
+Element* nsFocusManager::GetRootForFocus(nsPIDOMWindowOuter* aWindow,
+                                         Document* aDocument,
+                                         bool aForDocumentNavigation,
+                                         bool aCheckVisibility) {
+  if (!aForDocumentNavigation) {
+    nsCOMPtr<nsIDocShell> docShell = aWindow->GetDocShell();
+    if (docShell->ItemType() == nsIDocShellTreeItem::typeChrome) {
+      return nullptr;
+    }
+  }
+
+  if (aCheckVisibility && !IsWindowVisible(aWindow)) return nullptr;
+
+  // If the body is contenteditable, use the editor's root element rather than
+  // the actual root element.
+  RefPtr<Element> rootElement =
+      nsLayoutUtils::GetEditableRootContentByContentEditable(aDocument);
+  if (!rootElement || !rootElement->GetPrimaryFrame()) {
+    rootElement = aDocument->GetRootElement();
+    if (!rootElement) {
+      return nullptr;
+    }
+  }
+
+  if (aCheckVisibility && !rootElement->GetPrimaryFrame()) {
+    return nullptr;
+  }
+
+  // Finally, check if this is a frameset
+  if (aDocument && aDocument->IsHTMLOrXHTML()) {
+    Element* htmlChild = aDocument->GetHtmlChildElement(nsGkAtoms::frameset);
+    if (htmlChild) {
+      // In document navigation mode, return the frameset so that navigation
+      // descends into the child frames.
+      return aForDocumentNavigation ? htmlChild : nullptr;
+    }
+  }
+
+  return rootElement;
+}
+
+Element* nsFocusManager::GetRootForChildDocument(nsIContent* aContent) {
+  // Check for elements that represent child documents, that is, browsers,
+  // editors or frames from a frameset. We don't include iframes since we
+  // consider them to be an integral part of the same window or page.
+  if (!aContent || !(aContent->IsXULElement(nsGkAtoms::browser) ||
+                     aContent->IsXULElement(nsGkAtoms::editor) ||
+                     aContent->IsHTMLElement(nsGkAtoms::frame))) {
+    return nullptr;
+  }
+
+  Document* doc = aContent->GetComposedDoc();
+  if (!doc) {
+    return nullptr;
+  }
+
+  Document* subdoc = doc->GetSubDocumentFor(aContent);
+  if (!subdoc || subdoc->EventHandlingSuppressed()) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> window = subdoc->GetWindow();
+  return GetRootForFocus(window, subdoc, true, true);
+}
+
+static bool IsLink(nsIContent* aContent) {
+  return aContent->IsElement() && aContent->AsElement()->IsLink();
+}
+
+void nsFocusManager::GetFocusInSelection(nsPIDOMWindowOuter* aWindow,
+                                         nsIContent* aStartSelection,
+                                         nsIContent* aEndSelection,
+                                         nsIContent** aFocusedContent) {
+  *aFocusedContent = nullptr;
+
+  nsCOMPtr<nsIContent> testContent = aStartSelection;
+  nsCOMPtr<nsIContent> nextTestContent = aEndSelection;
+
+  nsCOMPtr<nsIContent> currentFocus = aWindow->GetFocusedElement();
+
+  // We now have the correct start node in selectionContent!
+  // Search for focusable elements, starting with selectionContent
+
+  // Method #1: Keep going up while we look - an ancestor might be focusable
+  // We could end the loop earlier, such as when we're no longer
+  // in the same frame, by comparing selectionContent->GetPrimaryFrame()
+  // with a variable holding the starting selectionContent
+  while (testContent) {
+    // Keep testing while selectionContent is equal to something,
+    // eventually we'll run out of ancestors
+
+    if (testContent == currentFocus || IsLink(testContent)) {
+      testContent.forget(aFocusedContent);
+      return;
+    }
+
+    // Get the parent
+    testContent = testContent->GetParent();
+
+    if (!testContent) {
+      // We run this loop again, checking the ancestor chain of the selection's
+      // end point
+      testContent = nextTestContent;
+      nextTestContent = nullptr;
+    }
+  }
+
+  // We couldn't find an anchor that was an ancestor of the selection start
+  // Method #2: look for anchor in selection's primary range (depth first
+  // search)
+
+  nsCOMPtr<nsIContent> selectionNode = aStartSelection;
+  nsCOMPtr<nsIContent> endSelectionNode = aEndSelection;
+  nsCOMPtr<nsIContent> testNode;
+
+  do {
+    testContent = selectionNode;
+
+    // We're looking for any focusable link that could be part of the
+    // main document's selection.
+    if (testContent == currentFocus || IsLink(testContent)) {
+      testContent.forget(aFocusedContent);
+      return;
+    }
+
+    nsIContent* testNode = selectionNode->GetFirstChild();
+    if (testNode) {
+      selectionNode = testNode;
+      continue;
+    }
+
+    if (selectionNode == endSelectionNode) {
+      break;
+    }
+    testNode = selectionNode->GetNextSibling();
+    if (testNode) {
+      selectionNode = testNode;
+      continue;
+    }
+
+    do {
+      // GetParent is OK here, instead of GetParentNode, because the only case
+      // where the latter returns something different from the former is when
+      // GetParentNode is the document.  But in that case we would simply get
+      // null for selectionNode when setting it to testNode->GetNextSibling()
+      // (because a document has no next sibling).  And then the next iteration
+      // of this loop would get null for GetParentNode anyway, and break out of
+      // all the loops.
+      testNode = selectionNode->GetParent();
+      if (!testNode || testNode == endSelectionNode) {
+        selectionNode = nullptr;
+        break;
+      }
+      selectionNode = testNode->GetNextSibling();
+      if (selectionNode) {
+        break;
+      }
+      selectionNode = testNode;
+    } while (true);
+  } while (selectionNode && selectionNode != endSelectionNode);
+}
+
+static void MaybeUnlockPointer(BrowsingContext* aCurrentFocusedContext) {
+  if (!PointerLockManager::IsInLockContext(aCurrentFocusedContext)) {
+    PointerLockManager::Unlock();
+  }
+}
+
+class PointerUnlocker : public Runnable {
+ public:
+  PointerUnlocker() : mozilla::Runnable("PointerUnlocker") {
+    MOZ_ASSERT(XRE_IsParentProcess());
+    MOZ_ASSERT(!PointerUnlocker::sActiveUnlocker);
+    PointerUnlocker::sActiveUnlocker = this;
+  }
+
+  ~PointerUnlocker() {
+    if (PointerUnlocker::sActiveUnlocker == this) {
+      PointerUnlocker::sActiveUnlocker = nullptr;
+    }
+  }
+
+  NS_IMETHOD Run() override {
+    if (PointerUnlocker::sActiveUnlocker == this) {
+      PointerUnlocker::sActiveUnlocker = nullptr;
+    }
+    NS_ENSURE_STATE(nsFocusManager::GetFocusManager());
+    nsPIDOMWindowOuter* focused =
+        nsFocusManager::GetFocusManager()->GetFocusedWindow();
+    MaybeUnlockPointer(focused ? focused->GetBrowsingContext() : nullptr);
+    return NS_OK;
+  }
+
+  static PointerUnlocker* sActiveUnlocker;
+};
+
+PointerUnlocker* PointerUnlocker::sActiveUnlocker = nullptr;
+
+void nsFocusManager::SetFocusedBrowsingContext(BrowsingContext* aContext,
+                                               uint64_t aActionId) {
+  if (XRE_IsParentProcess()) {
+    return;
+  }
+  MOZ_ASSERT(!ActionIdComparableAndLower(
+      aActionId, mActionIdForFocusedBrowsingContextInContent));
+  mFocusedBrowsingContextInContent = aContext;
+  mActionIdForFocusedBrowsingContextInContent = aActionId;
+  if (aContext) {
+    // We don't send the unset but instead expect the set from
+    // elsewhere to take care of it. XXX Is that bad?
+    MOZ_ASSERT(aContext->IsInProcess());
+    mozilla::dom::ContentChild* contentChild =
+        mozilla::dom::ContentChild::GetSingleton();
+    MOZ_ASSERT(contentChild);
+    contentChild->SendSetFocusedBrowsingContext(aContext, aActionId);
+  }
+}
+
+void nsFocusManager::SetFocusedBrowsingContextFromOtherProcess(
+    BrowsingContext* aContext, uint64_t aActionId) {
+  MOZ_ASSERT(!XRE_IsParentProcess());
+  MOZ_ASSERT(aContext);
+  if (ActionIdComparableAndLower(aActionId,
+                                 mActionIdForFocusedBrowsingContextInContent)) {
+    // Unclear if this ever happens.
+    LOGFOCUS(
+        ("Ignored an attempt to set an in-process BrowsingContext [%p] as "
+         "focused from another process due to stale action id %" PRIu64 ".",
+         aContext, aActionId));
+    return;
+  }
+  if (aContext->IsInProcess()) {
+    // This message has been in transit for long enough that
+    // the process association of aContext has changed since
+    // the other content process sent the message, because
+    // an iframe in that process became an out-of-process
+    // iframe while the IPC broadcast that we're receiving
+    // was in-flight. Let's just ignore this.
+    LOGFOCUS(
+        ("Ignored an attempt to set an in-process BrowsingContext [%p] as "
+         "focused from another process, actionid: %" PRIu64 ".",
+         aContext, aActionId));
+    return;
+  }
+  mFocusedBrowsingContextInContent = aContext;
+  mActionIdForFocusedBrowsingContextInContent = aActionId;
+  mFocusedElement = nullptr;
+  mFocusedWindow = nullptr;
+}
+
+bool nsFocusManager::SetFocusedBrowsingContextInChrome(
+    mozilla::dom::BrowsingContext* aContext, uint64_t aActionId) {
+  MOZ_ASSERT(aActionId);
+  if (ProcessPendingFocusedBrowsingContextActionId(aActionId)) {
+    MOZ_DIAGNOSTIC_ASSERT(!ActionIdComparableAndLower(
+        aActionId, mActionIdForFocusedBrowsingContextInChrome));
+    mFocusedBrowsingContextInChrome = aContext;
+    mActionIdForFocusedBrowsingContextInChrome = aActionId;
+    return true;
+  }
+  return false;
+}
+
+BrowsingContext* nsFocusManager::GetFocusedBrowsingContextInChrome() {
+  return mFocusedBrowsingContextInChrome;
+}
+
+void nsFocusManager::BrowsingContextDetached(BrowsingContext* aContext) {
+  if (mFocusedBrowsingContextInChrome == aContext) {
+    mFocusedBrowsingContextInChrome = nullptr;
+    // Deliberately not adjusting the corresponding action id, because
+    // we don't want changes from the past to take effect.
+  }
+  if (mActiveBrowsingContextInChrome == aContext) {
+    mActiveBrowsingContextInChrome = nullptr;
+    // Deliberately not adjusting the corresponding action id, because
+    // we don't want changes from the past to take effect.
+  }
+}
+
+void nsFocusManager::SetActiveBrowsingContextInContent(
+    mozilla::dom::BrowsingContext* aContext, uint64_t aActionId) {
+  MOZ_ASSERT(!XRE_IsParentProcess());
+  MOZ_ASSERT(!aContext || aContext->IsInProcess());
+  mozilla::dom::ContentChild* contentChild =
+      mozilla::dom::ContentChild::GetSingleton();
+  MOZ_ASSERT(contentChild);
+
+  if (ActionIdComparableAndLower(aActionId,
+                                 mActionIdForActiveBrowsingContextInContent)) {
+    LOGFOCUS(
+        ("Ignored an attempt to set an in-process BrowsingContext [%p] as "
+         "the active browsing context due to a stale action id %" PRIu64 ".",
+         aContext, aActionId));
+    return;
+  }
+
+  if (aContext != mActiveBrowsingContextInContent) {
+    if (aContext) {
+      contentChild->SendSetActiveBrowsingContext(aContext, aActionId);
+    } else if (mActiveBrowsingContextInContent) {
+      // We want to sync this over only if this isn't happening
+      // due to the active BrowsingContext switching processes,
+      // in which case the BrowserChild has already marked itself
+      // as destroying.
+      nsPIDOMWindowOuter* outer =
+          mActiveBrowsingContextInContent->GetDOMWindow();
+      if (outer) {
+        nsPIDOMWindowInner* inner = outer->GetCurrentInnerWindow();
+        if (inner) {
+          WindowGlobalChild* globalChild = inner->GetWindowGlobalChild();
+          if (globalChild) {
+            RefPtr<BrowserChild> browserChild = globalChild->GetBrowserChild();
+            if (browserChild && !browserChild->IsDestroyed()) {
+              contentChild->SendUnsetActiveBrowsingContext(
+                  mActiveBrowsingContextInContent, aActionId);
+            }
+          }
+        }
+      }
+    }
+  }
+  mActiveBrowsingContextInContentSetFromOtherProcess = false;
+  mActiveBrowsingContextInContent = aContext;
+  mActionIdForActiveBrowsingContextInContent = aActionId;
+  MaybeUnlockPointer(aContext);
+}
+
+void nsFocusManager::SetActiveBrowsingContextFromOtherProcess(
+    BrowsingContext* aContext, uint64_t aActionId) {
+  MOZ_ASSERT(!XRE_IsParentProcess());
+  MOZ_ASSERT(aContext);
+  if (ActionIdComparableAndLower(aActionId,
+                                 mActionIdForActiveBrowsingContextInContent)) {
+    LOGFOCUS(
+        ("Ignored an attempt to set active BrowsingContext [%p] from "
+         "another process due to a stale action id %" PRIu64 ".",
+         aContext, aActionId));
+    return;
+  }
+  if (aContext->IsInProcess()) {
+    // This message has been in transit for long enough that
+    // the process association of aContext has changed since
+    // the other content process sent the message, because
+    // an iframe in that process became an out-of-process
+    // iframe while the IPC broadcast that we're receiving
+    // was in-flight. Let's just ignore this.
+    LOGFOCUS(
+        ("Ignored an attempt to set an in-process BrowsingContext [%p] as "
+         "active from another process. actionid: %" PRIu64,
+         aContext, aActionId));
+    return;
+  }
+  mActiveBrowsingContextInContentSetFromOtherProcess = true;
+  mActiveBrowsingContextInContent = aContext;
+  mActionIdForActiveBrowsingContextInContent = aActionId;
+  MaybeUnlockPointer(aContext);
+}
+
+void nsFocusManager::UnsetActiveBrowsingContextFromOtherProcess(
+    BrowsingContext* aContext, uint64_t aActionId) {
+  MOZ_ASSERT(!XRE_IsParentProcess());
+  MOZ_ASSERT(aContext);
+  if (ActionIdComparableAndLower(aActionId,
+                                 mActionIdForActiveBrowsingContextInContent)) {
+    LOGFOCUS(
+        ("Ignored an attempt to unset the active BrowsingContext [%p] from "
+         "another process due to stale action id: %" PRIu64 ".",
+         aContext, aActionId));
+    return;
+  }
+  if (mActiveBrowsingContextInContent == aContext) {
+    mActiveBrowsingContextInContent = nullptr;
+    mActionIdForActiveBrowsingContextInContent = aActionId;
+    MaybeUnlockPointer(nullptr);
+  } else {
+    LOGFOCUS(
+        ("Ignored an attempt to unset the active BrowsingContext [%p] from "
+         "another process. actionid: %" PRIu64,
+         aContext, aActionId));
+  }
+}
+
+void nsFocusManager::ReviseActiveBrowsingContext(
+    uint64_t aOldActionId, mozilla::dom::BrowsingContext* aContext,
+    uint64_t aNewActionId) {
+  MOZ_ASSERT(XRE_IsContentProcess());
+  if (mActionIdForActiveBrowsingContextInContent == aOldActionId) {
+    LOGFOCUS(("Revising the active BrowsingContext [%p]. old actionid: %" PRIu64
+              ", new "
+              "actionid: %" PRIu64,
+              aContext, aOldActionId, aNewActionId));
+    mActiveBrowsingContextInContent = aContext;
+    mActionIdForActiveBrowsingContextInContent = aNewActionId;
+  } else {
+    LOGFOCUS(
+        ("Ignored a stale attempt to revise the active BrowsingContext [%p]. "
+         "old actionid: %" PRIu64 ", new actionid: %" PRIu64,
+         aContext, aOldActionId, aNewActionId));
+  }
+}
+
+void nsFocusManager::ReviseFocusedBrowsingContext(
+    uint64_t aOldActionId, mozilla::dom::BrowsingContext* aContext,
+    uint64_t aNewActionId) {
+  MOZ_ASSERT(XRE_IsContentProcess());
+  if (mActionIdForFocusedBrowsingContextInContent == aOldActionId) {
+    LOGFOCUS(
+        ("Revising the focused BrowsingContext [%p]. old actionid: %" PRIu64
+         ", new "
+         "actionid: %" PRIu64,
+         aContext, aOldActionId, aNewActionId));
+    mFocusedBrowsingContextInContent = aContext;
+    mActionIdForFocusedBrowsingContextInContent = aNewActionId;
+    mFocusedElement = nullptr;
+  } else {
+    LOGFOCUS(
+        ("Ignored a stale attempt to revise the focused BrowsingContext [%p]. "
+         "old actionid: %" PRIu64 ", new actionid: %" PRIu64,
+         aContext, aOldActionId, aNewActionId));
+  }
+}
+
+bool nsFocusManager::SetActiveBrowsingContextInChrome(
+    mozilla::dom::BrowsingContext* aContext, uint64_t aActionId) {
+  MOZ_ASSERT(aActionId);
+  if (ProcessPendingActiveBrowsingContextActionId(aActionId, aContext)) {
+    MOZ_DIAGNOSTIC_ASSERT(!ActionIdComparableAndLower(
+        aActionId, mActionIdForActiveBrowsingContextInChrome));
+    mActiveBrowsingContextInChrome = aContext;
+    mActionIdForActiveBrowsingContextInChrome = aActionId;
+    return true;
+  }
+  return false;
+}
+
+uint64_t nsFocusManager::GetActionIdForActiveBrowsingContextInChrome() const {
+  return mActionIdForActiveBrowsingContextInChrome;
+}
+
+uint64_t nsFocusManager::GetActionIdForFocusedBrowsingContextInChrome() const {
+  return mActionIdForFocusedBrowsingContextInChrome;
+}
+
+BrowsingContext* nsFocusManager::GetActiveBrowsingContextInChrome() {
+  return mActiveBrowsingContextInChrome;
+}
+
+void nsFocusManager::InsertNewFocusActionId(uint64_t aActionId) {
+  LOGFOCUS(("InsertNewFocusActionId %" PRIu64, aActionId));
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(!mPendingActiveBrowsingContextActions.Contains(aActionId));
+  mPendingActiveBrowsingContextActions.AppendElement(aActionId);
+  MOZ_ASSERT(!mPendingFocusedBrowsingContextActions.Contains(aActionId));
+  mPendingFocusedBrowsingContextActions.AppendElement(aActionId);
+}
+
+static void RemoveContentInitiatedActionsUntil(
+    nsTArray<uint64_t>& aPendingActions,
+    nsTArray<uint64_t>::index_type aUntil) {
+  nsTArray<uint64_t>::index_type i = 0;
+  while (i < aUntil) {
+    auto [actionProc, actionId] =
+        nsContentUtils::SplitProcessSpecificId(aPendingActions[i]);
+    Unused << actionId;
+    if (actionProc) {
+      aPendingActions.RemoveElementAt(i);
+      --aUntil;
+      continue;
+    }
+    ++i;
+  }
+}
+
+bool nsFocusManager::ProcessPendingActiveBrowsingContextActionId(
+    uint64_t aActionId, bool aSettingToNonNull) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  auto index = mPendingActiveBrowsingContextActions.IndexOf(aActionId);
+  if (index == nsTArray<uint64_t>::NoIndex) {
+    return false;
+  }
+  // When aSettingToNonNull is true, we need to remove one more
+  // element to remove the action id itself in addition to
+  // removing the older ones.
+  if (aSettingToNonNull) {
+    index++;
+  }
+  auto [actionProc, actionId] =
+      nsContentUtils::SplitProcessSpecificId(aActionId);
+  Unused << actionId;
+  if (actionProc) {
+    // Action from content: We allow parent-initiated actions
+    // to take precedence over content-initiated ones, so we
+    // remove only prior content-initiated actions.
+    RemoveContentInitiatedActionsUntil(mPendingActiveBrowsingContextActions,
+                                       index);
+  } else {
+    // Action from chrome
+    mPendingActiveBrowsingContextActions.RemoveElementsAt(0, index);
+  }
+  return true;
+}
+
+bool nsFocusManager::ProcessPendingFocusedBrowsingContextActionId(
+    uint64_t aActionId) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  auto index = mPendingFocusedBrowsingContextActions.IndexOf(aActionId);
+  if (index == nsTArray<uint64_t>::NoIndex) {
+    return false;
+  }
+
+  auto [actionProc, actionId] =
+      nsContentUtils::SplitProcessSpecificId(aActionId);
+  Unused << actionId;
+  if (actionProc) {
+    // Action from content: We allow parent-initiated actions
+    // to take precedence over content-initiated ones, so we
+    // remove only prior content-initiated actions.
+    RemoveContentInitiatedActionsUntil(mPendingFocusedBrowsingContextActions,
+                                       index);
+  } else {
+    // Action from chrome
+    mPendingFocusedBrowsingContextActions.RemoveElementsAt(0, index);
+  }
+  return true;
+}
+
+// static
+uint64_t nsFocusManager::GenerateFocusActionId() {
+  uint64_t id =
+      nsContentUtils::GenerateProcessSpecificId(++sFocusActionCounter);
+  if (XRE_IsParentProcess()) {
+    nsFocusManager* fm = GetFocusManager();
+    if (fm) {
+      fm->InsertNewFocusActionId(id);
+    }
+  } else {
+    mozilla::dom::ContentChild* contentChild =
+        mozilla::dom::ContentChild::GetSingleton();
+    MOZ_ASSERT(contentChild);
+    contentChild->SendInsertNewFocusActionId(id);
+  }
+  LOGFOCUS(("GenerateFocusActionId %" PRIu64, id));
+  return id;
+}
+
+static bool IsInPointerLockContext(nsPIDOMWindowOuter* aWin) {
+  return PointerLockManager::IsInLockContext(aWin ? aWin->GetBrowsingContext()
+                                                  : nullptr);
+}
+
+void nsFocusManager::SetFocusedWindowInternal(nsPIDOMWindowOuter* aWindow,
+                                              uint64_t aActionId,
+                                              bool aSyncBrowsingContext) {
+  if (XRE_IsParentProcess() && !PointerUnlocker::sActiveUnlocker &&
+      IsInPointerLockContext(mFocusedWindow) &&
+      !IsInPointerLockContext(aWindow)) {
+    nsCOMPtr<nsIRunnable> runnable = new PointerUnlocker();
+    NS_DispatchToCurrentThread(runnable);
+  }
+
+  // Update the last focus time on any affected documents
+  if (aWindow && aWindow != mFocusedWindow) {
+    const TimeStamp now(TimeStamp::Now());
+    for (Document* doc = aWindow->GetExtantDoc(); doc;
+         doc = doc->GetInProcessParentDocument()) {
+      doc->SetLastFocusTime(now);
+    }
+  }
+
+  // This function may be called with zero action id to indicate that the
+  // action id should be ignored.
+  if (XRE_IsContentProcess() && aActionId &&
+      ActionIdComparableAndLower(aActionId,
+                                 mActionIdForFocusedBrowsingContextInContent)) {
+    // Unclear if this ever happens.
+    LOGFOCUS(
+        ("Ignored an attempt to set an in-process BrowsingContext as "
+         "focused due to stale action id %" PRIu64 ".",
+         aActionId));
+    return;
+  }
+
+  mFocusedWindow = aWindow;
+  BrowsingContext* bc = aWindow ? aWindow->GetBrowsingContext() : nullptr;
+  if (aSyncBrowsingContext) {
+    MOZ_ASSERT(aActionId,
+               "aActionId must not be zero if aSyncBrowsingContext is true");
+    SetFocusedBrowsingContext(bc, aActionId);
+  } else if (XRE_IsContentProcess()) {
+    MOZ_ASSERT(mFocusedBrowsingContextInContent == bc,
+               "Not syncing BrowsingContext even when different.");
+  }
+}
+
+void nsFocusManager::NotifyOfReFocus(Element& aElement) {
+  nsPIDOMWindowOuter* window = GetCurrentWindow(&aElement);
+  if (!window || window != mFocusedWindow) {
+    return;
+  }
+  if (!aElement.IsInComposedDoc() || IsNonFocusableRoot(&aElement)) {
+    return;
+  }
+  nsIDocShell* docShell = window->GetDocShell();
+  if (!docShell) {
+    return;
+  }
+  RefPtr<PresShell> presShell = docShell->GetPresShell();
+  if (!presShell) {
+    return;
+  }
+  RefPtr<nsPresContext> presContext = presShell->GetPresContext();
+  if (!presContext) {
+    return;
+  }
+  IMEStateManager::OnReFocus(*presContext, aElement);
+}
+
+void nsFocusManager::MarkUncollectableForCCGeneration(uint32_t aGeneration) {
+  if (!sInstance) {
+    return;
+  }
+
+  if (sInstance->mActiveWindow) {
+    sInstance->mActiveWindow->MarkUncollectableForCCGeneration(aGeneration);
+  }
+  if (sInstance->mFocusedWindow) {
+    sInstance->mFocusedWindow->MarkUncollectableForCCGeneration(aGeneration);
+  }
+  if (sInstance->mWindowBeingLowered) {
+    sInstance->mWindowBeingLowered->MarkUncollectableForCCGeneration(
+        aGeneration);
+  }
+  if (sInstance->mFocusedElement) {
+    sInstance->mFocusedElement->OwnerDoc()->MarkUncollectableForCCGeneration(
+        aGeneration);
+  }
+  if (sInstance->mFirstBlurEvent) {
+    sInstance->mFirstBlurEvent->OwnerDoc()->MarkUncollectableForCCGeneration(
+        aGeneration);
+  }
+  if (sInstance->mFirstFocusEvent) {
+    sInstance->mFirstFocusEvent->OwnerDoc()->MarkUncollectableForCCGeneration(
+        aGeneration);
+  }
+}
+
+bool nsFocusManager::CanSkipFocus(nsIContent* aContent) {
+  if (!aContent) {
+    return false;
+  }
+
+  if (mFocusedElement == aContent) {
+    return true;
+  }
+
+  nsIDocShell* ds = aContent->OwnerDoc()->GetDocShell();
+  if (!ds) {
+    return true;
+  }
+
+  if (XRE_IsParentProcess()) {
+    nsCOMPtr<nsIDocShellTreeItem> root;
+    ds->GetInProcessRootTreeItem(getter_AddRefs(root));
+    nsCOMPtr<nsPIDOMWindowOuter> newRootWindow =
+        root ? root->GetWindow() : nullptr;
+    if (mActiveWindow != newRootWindow) {
+      nsPIDOMWindowOuter* outerWindow = aContent->OwnerDoc()->GetWindow();
+      if (outerWindow && outerWindow->GetFocusedElement() == aContent) {
+        return true;
+      }
+    }
+  } else {
+    BrowsingContext* bc = aContent->OwnerDoc()->GetBrowsingContext();
+    BrowsingContext* top = bc ? bc->Top() : nullptr;
+    if (GetActiveBrowsingContext() != top) {
+      nsPIDOMWindowOuter* outerWindow = aContent->OwnerDoc()->GetWindow();
+      if (outerWindow && outerWindow->GetFocusedElement() == aContent) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+/* static */
+Element* nsFocusManager::GetTheFocusableArea(Element* aTarget,
+                                             uint32_t aFlags) {
+  MOZ_ASSERT(aTarget);
+  nsIFrame* frame = aTarget->GetPrimaryFrame();
+  if (!frame) {
+    return nullptr;
+  }
+
+  // If focus target is the document element of its Document.
+  if (aTarget == aTarget->OwnerDoc()->GetRootElement()) {
+    // the root content can always be focused,
+    // except in userfocusignored context.
+    return aTarget;
+  }
+
+  // If focus target is an area element with one or more shapes that are
+  // focusable areas.
+  if (aTarget->IsHTMLElement(nsGkAtoms::area)) {
+    // HTML areas do not have their own frame, and the img frame we get from
+    // GetPrimaryFrame() is not relevant as to whether it is focusable or
+    // not, so we have to do all the relevant checks manually for them.
+    return frame->IsVisibleConsideringAncestors() && aTarget->IsFocusable()
+               ? aTarget
+               : nullptr;
+  }
+
+  // For these 3 steps mentioned in the spec
+  //   1. If focus target is an element with one or more scrollable regions that
+  //   are focusable areas
+  //   2. If focus target is a navigable
+  //   3. If focus target is a navigable container with a non-null content
+  //   navigable
+  // nsIFrame::IsFocusable will effectively perform the checks for them.
+  if (frame->IsFocusable(aFlags & FLAG_BYMOUSE)) {
+    return aTarget;
+  }
+
+  // If focus target is a shadow host whose shadow root's delegates focus is
+  // true
+  if (ShadowRoot* root = aTarget->GetShadowRoot()) {
+    if (root->DelegatesFocus()) {
+      // If focus target is a shadow-including inclusive ancestor of the
+      // currently focused area of a top-level browsing context's DOM anchor,
+      // then return the already-focused element.
+      if (nsPIDOMWindowInner* innerWindow =
+              aTarget->OwnerDoc()->GetInnerWindow()) {
+        if (Element* focusedElement = innerWindow->GetFocusedElement()) {
+          if (focusedElement->IsShadowIncludingInclusiveDescendantOf(aTarget)) {
+            return focusedElement;
+          }
+        }
+      }
+
+      if (Element* firstFocusable =
+              root->GetFocusDelegate(aFlags & FLAG_BYMOUSE)) {
+        return firstFocusable;
+      }
+    }
+  }
+  return nullptr;
+}
+
+nsresult NS_NewFocusManager(nsIFocusManager** aResult) {
+  NS_IF_ADDREF(*aResult = nsFocusManager::GetFocusManager());
+  return NS_OK;
+}
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