Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 2363 insertions, 0 deletions

diff --git a/dom/events/IMEStateManager.cpp b/dom/events/IMEStateManager.cpp
new file mode 100644
index 0000000000..2477f74a9c
--- /dev/null
+++ b/dom/events/IMEStateManager.cpp
@@ -0,0 +1,2363 @@
+/* -*- 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 "IMEStateManager.h"
+
+#include "mozilla/Logging.h"
+
+#include "mozilla/Attributes.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/EditorBase.h"
+#include "mozilla/EventListenerManager.h"
+#include "mozilla/EventStateManager.h"
+#include "mozilla/HTMLEditor.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/StaticPrefs_intl.h"
+#include "mozilla/TextComposition.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/ToString.h"
+#include "mozilla/Unused.h"
+#include "mozilla/dom/BrowserBridgeChild.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/HTMLFormElement.h"
+#include "mozilla/dom/HTMLTextAreaElement.h"
+#include "mozilla/dom/MouseEventBinding.h"
+#include "mozilla/dom/UserActivation.h"
+
+#include "HTMLInputElement.h"
+#include "IMEContentObserver.h"
+
+#include "nsCOMPtr.h"
+#include "nsContentUtils.h"
+#include "nsFocusManager.h"
+#include "nsIContent.h"
+#include "nsIContentInlines.h"
+#include "nsIFormControl.h"
+#include "nsINode.h"
+#include "nsISupports.h"
+#include "nsIURI.h"
+#include "nsIURIMutator.h"
+#include "nsPresContext.h"
+
+namespace mozilla {
+
+using namespace dom;
+using namespace widget;
+
+/**
+ * When a method is called, log its arguments and/or related static variables
+ * with LogLevel::Info.  However, if it puts too many logs like
+ * OnDestroyPresContext(), should long only when the method actually does
+ * something. In this case, the log should start with "<method name>".
+ *
+ * When a method quits due to unexpected situation, log the reason with
+ * LogLevel::Error.  In this case, the log should start with
+ * "<method name>(), FAILED".  The indent makes the log look easier.
+ *
+ * When a method does something only in some situations and it may be important
+ * for debug, log the information with LogLevel::Debug.  In this case, the log
+ * should start with "  <method name>(),".
+ */
+LazyLogModule sISMLog("IMEStateManager");
+
+static const char* GetBoolName(bool aBool) { return aBool ? "true" : "false"; }
+
+StaticRefPtr<Element> IMEStateManager::sFocusedElement;
+StaticRefPtr<nsPresContext> IMEStateManager::sFocusedPresContext;
+nsIWidget* IMEStateManager::sTextInputHandlingWidget = nullptr;
+nsIWidget* IMEStateManager::sFocusedIMEWidget = nullptr;
+StaticRefPtr<BrowserParent> IMEStateManager::sFocusedIMEBrowserParent;
+nsIWidget* IMEStateManager::sActiveInputContextWidget = nullptr;
+StaticRefPtr<IMEContentObserver> IMEStateManager::sActiveIMEContentObserver;
+TextCompositionArray* IMEStateManager::sTextCompositions = nullptr;
+InputContext::Origin IMEStateManager::sOrigin = InputContext::ORIGIN_MAIN;
+InputContext IMEStateManager::sActiveChildInputContext;
+bool IMEStateManager::sInstalledMenuKeyboardListener = false;
+bool IMEStateManager::sIsGettingNewIMEState = false;
+bool IMEStateManager::sCleaningUpForStoppingIMEStateManagement = false;
+bool IMEStateManager::sIsActive = false;
+Maybe<IMEStateManager::PendingFocusedBrowserSwitchingData>
+    IMEStateManager::sPendingFocusedBrowserSwitchingData;
+
+// static
+void IMEStateManager::Init() {
+  sOrigin = XRE_IsParentProcess() ? InputContext::ORIGIN_MAIN
+                                  : InputContext::ORIGIN_CONTENT;
+  ResetActiveChildInputContext();
+}
+
+// static
+void IMEStateManager::Shutdown() {
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("Shutdown(), sTextCompositions=0x%p, sTextCompositions->Length()=%zu, "
+       "sPendingFocusedBrowserSwitchingData.isSome()=%s",
+       sTextCompositions, sTextCompositions ? sTextCompositions->Length() : 0,
+       GetBoolName(sPendingFocusedBrowserSwitchingData.isSome())));
+  MOZ_LOG(sISMLog, LogLevel::Debug,
+          ("  Shutdown(), sFocusedElement=0x%p, sFocusedPresContext=0x%p, "
+           "sTextInputHandlingWidget=0x%p, sFocusedIMEWidget=0x%p, "
+           "sFocusedIMEBrowserParent=0x%p, sActiveInputContextWidget=0x%p, "
+           "sActiveIMEContentObserver=0x%p",
+           sFocusedElement.get(), sFocusedPresContext.get(),
+           sTextInputHandlingWidget, sFocusedIMEWidget,
+           sFocusedIMEBrowserParent.get(), sActiveInputContextWidget,
+           sActiveIMEContentObserver.get()));
+
+  sPendingFocusedBrowserSwitchingData.reset();
+  MOZ_ASSERT(!sTextCompositions || !sTextCompositions->Length());
+  delete sTextCompositions;
+  sTextCompositions = nullptr;
+  // All string instances in the global space need to be empty after XPCOM
+  // shutdown.
+  sActiveChildInputContext.ShutDown();
+}
+
+// static
+void IMEStateManager::OnFocusMovedBetweenBrowsers(BrowserParent* aBlur,
+                                                  BrowserParent* aFocus) {
+  MOZ_ASSERT(aBlur != aFocus);
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  if (sPendingFocusedBrowserSwitchingData.isSome()) {
+    MOZ_ASSERT(aBlur ==
+               sPendingFocusedBrowserSwitchingData.ref().mBrowserParentFocused);
+    // If focus is not changed between browsers actually, we need to do
+    // nothing here.  Let's cancel handling what this method does.
+    if (sPendingFocusedBrowserSwitchingData.ref().mBrowserParentBlurred ==
+        aFocus) {
+      sPendingFocusedBrowserSwitchingData.reset();
+      MOZ_LOG(sISMLog, LogLevel::Info,
+              ("  OnFocusMovedBetweenBrowsers(), canceled all pending focus "
+               "moves between browsers"));
+      return;
+    }
+    aBlur = sPendingFocusedBrowserSwitchingData.ref().mBrowserParentBlurred;
+    sPendingFocusedBrowserSwitchingData.ref().mBrowserParentFocused = aFocus;
+    MOZ_ASSERT(aBlur != aFocus);
+  }
+
+  // If application was inactive, but is now activated, and the last focused
+  // this is called by BrowserParent::UnsetTopLevelWebFocusAll() from
+  // nsFocusManager::WindowRaised().  If a content has focus in a remote
+  // process and it has composition, it may get focus back later and the
+  // composition shouldn't be commited now.  Therefore, we should put off to
+  // handle this until getting another call of this method or a call of
+  //`OnFocusChangeInternal()`.
+  if (aBlur && !aFocus && !sIsActive && sTextInputHandlingWidget &&
+      sTextCompositions &&
+      sTextCompositions->GetCompositionFor(sTextInputHandlingWidget)) {
+    if (sPendingFocusedBrowserSwitchingData.isNothing()) {
+      sPendingFocusedBrowserSwitchingData.emplace(aBlur, aFocus);
+    }
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnFocusMovedBetweenBrowsers(), put off to handle it until "
+             "next OnFocusChangeInternal() call"));
+    return;
+  }
+  sPendingFocusedBrowserSwitchingData.reset();
+
+  const nsCOMPtr<nsIWidget> oldWidget = sTextInputHandlingWidget;
+  // In the chrome-process case, we'll get sTextInputHandlingWidget from a
+  // PresShell later.
+  sTextInputHandlingWidget =
+      aFocus ? nsCOMPtr<nsIWidget>(aFocus->GetTextInputHandlingWidget()).get()
+             : nullptr;
+  if (oldWidget && sTextCompositions) {
+    RefPtr<TextComposition> composition =
+        sTextCompositions->GetCompositionFor(oldWidget);
+    if (composition) {
+      MOZ_LOG(
+          sISMLog, LogLevel::Debug,
+          ("  OnFocusMovedBetweenBrowsers(), requesting to commit "
+           "composition to "
+           "the (previous) focused widget (would request=%s)",
+           GetBoolName(
+               !oldWidget->IMENotificationRequestsRef().WantDuringDeactive())));
+      NotifyIME(REQUEST_TO_COMMIT_COMPOSITION, oldWidget,
+                composition->GetBrowserParent());
+    }
+  }
+
+  // The manager check is to avoid telling the content process to stop
+  // IME state management after focus has already moved there between
+  // two same-process-hosted out-of-process iframes.
+  if (aBlur && (!aFocus || (aBlur->Manager() != aFocus->Manager()))) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnFocusMovedBetweenBrowsers(), notifying previous "
+             "focused child process of parent process or another child process "
+             "getting focus"));
+    aBlur->StopIMEStateManagement();
+  }
+
+  if (sActiveIMEContentObserver) {
+    DestroyIMEContentObserver();
+  }
+
+  if (sFocusedIMEWidget) {
+    // sFocusedIMEBrowserParent can be null, if IME focus hasn't been
+    // taken before BrowserParent blur.
+    // aBlur can be null when keyboard focus moves not actually
+    // between tabs but an open menu is involved.
+    MOZ_ASSERT(!sFocusedIMEBrowserParent || !aBlur ||
+               (sFocusedIMEBrowserParent == aBlur));
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnFocusMovedBetweenBrowsers(), notifying IME of blur"));
+    NotifyIME(NOTIFY_IME_OF_BLUR, sFocusedIMEWidget, sFocusedIMEBrowserParent);
+
+    MOZ_ASSERT(!sFocusedIMEBrowserParent);
+    MOZ_ASSERT(!sFocusedIMEWidget);
+
+  } else {
+    MOZ_ASSERT(!sFocusedIMEBrowserParent);
+  }
+
+  // We deliberately don't null out sFocusedElement or sFocusedPresContext here.
+  // When focus is in remote content, as far as layout in the chrome process is
+  // concerned, the corresponding content is the top-level XUL browser. Changes
+  // among out-of-process iframes don't change that, so dropping the pointer to
+  // the XUL browser upon such a change would break IME handling.
+}
+
+// static
+void IMEStateManager::WidgetDestroyed(nsIWidget* aWidget) {
+  MOZ_LOG(sISMLog, LogLevel::Debug,
+          ("WidgetDestroyed(aWidget=0x%p), sFocusedIMEWidget=0x%p, "
+           "sActiveInputContextWidget=0x%p, sFocusedIMEBrowserParent=0x%p",
+           aWidget, sFocusedIMEWidget, sActiveInputContextWidget,
+           sFocusedIMEBrowserParent.get()));
+  if (sTextInputHandlingWidget == aWidget) {
+    sTextInputHandlingWidget = nullptr;
+  }
+  if (sFocusedIMEWidget == aWidget) {
+    if (sFocusedIMEBrowserParent) {
+      OnFocusMovedBetweenBrowsers(sFocusedIMEBrowserParent, nullptr);
+      MOZ_ASSERT(!sFocusedIMEBrowserParent);
+    }
+    sFocusedIMEWidget = nullptr;
+  }
+  if (sActiveInputContextWidget == aWidget) {
+    sActiveInputContextWidget = nullptr;
+  }
+}
+
+// static
+void IMEStateManager::WidgetOnQuit(nsIWidget* aWidget) {
+  if (sFocusedIMEWidget == aWidget) {
+    MOZ_LOG(
+        sISMLog, LogLevel::Debug,
+        ("WidgetOnQuit(aWidget=0x%p (available %s)), sFocusedIMEWidget=0x%p",
+         aWidget, GetBoolName(aWidget && !aWidget->Destroyed()),
+         sFocusedIMEWidget));
+    // Notify IME of blur (which is done by IMEContentObserver::Destroy
+    // automatically) when the widget still has IME focus before forgetting the
+    // focused widget because the focused widget is required to clean up native
+    // IME handler with sending blur notification.  Fortunately, the widget
+    // has not been destroyed yet here since some methods to sending blur
+    // notification won't work with destroyed widget.
+    IMEStateManager::DestroyIMEContentObserver();
+    // Finally, clean up the widget and related objects for avoiding to leak.
+    IMEStateManager::WidgetDestroyed(aWidget);
+  }
+}
+
+// static
+void IMEStateManager::StopIMEStateManagement() {
+  MOZ_ASSERT(XRE_IsContentProcess());
+  MOZ_LOG(sISMLog, LogLevel::Info, ("StopIMEStateManagement()"));
+
+  // NOTE: Don't set input context from here since this has already lost
+  //       the rights to change input context.
+
+  // The requestee of this method in the main process must destroy its
+  // active IMEContentObserver for making existing composition end and
+  // make it be possible to start new composition in new focused process.
+  // Therefore, we shouldn't notify the main process of any changes which
+  // occurred after here.
+  AutoRestore<bool> restoreStoppingIMEStateManagementState(
+      sCleaningUpForStoppingIMEStateManagement);
+  sCleaningUpForStoppingIMEStateManagement = true;
+
+  if (sTextCompositions && sFocusedPresContext) {
+    NotifyIME(REQUEST_TO_COMMIT_COMPOSITION, sFocusedPresContext, nullptr);
+  }
+  sActiveInputContextWidget = nullptr;
+  sFocusedPresContext = nullptr;
+  sFocusedElement = nullptr;
+  sIsActive = false;
+  DestroyIMEContentObserver();
+}
+
+// static
+void IMEStateManager::MaybeStartOffsetUpdatedInChild(nsIWidget* aWidget,
+                                                     uint32_t aStartOffset) {
+  if (NS_WARN_IF(!sTextCompositions)) {
+    MOZ_LOG(sISMLog, LogLevel::Warning,
+            ("MaybeStartOffsetUpdatedInChild(aWidget=0x%p, aStartOffset=%u), "
+             "called when there is no composition",
+             aWidget, aStartOffset));
+    return;
+  }
+
+  RefPtr<TextComposition> composition = GetTextCompositionFor(aWidget);
+  if (NS_WARN_IF(!composition)) {
+    MOZ_LOG(sISMLog, LogLevel::Warning,
+            ("MaybeStartOffsetUpdatedInChild(aWidget=0x%p, aStartOffset=%u), "
+             "called when there is no composition",
+             aWidget, aStartOffset));
+    return;
+  }
+
+  if (composition->NativeOffsetOfStartComposition() == aStartOffset) {
+    return;
+  }
+
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("MaybeStartOffsetUpdatedInChild(aWidget=0x%p, aStartOffset=%u), "
+       "old offset=%u",
+       aWidget, aStartOffset, composition->NativeOffsetOfStartComposition()));
+  composition->OnStartOffsetUpdatedInChild(aStartOffset);
+}
+
+// static
+nsresult IMEStateManager::OnDestroyPresContext(nsPresContext& aPresContext) {
+  // First, if there is a composition in the aPresContext, clean up it.
+  if (sTextCompositions) {
+    TextCompositionArray::index_type i =
+        sTextCompositions->IndexOf(&aPresContext);
+    if (i != TextCompositionArray::NoIndex) {
+      MOZ_LOG(sISMLog, LogLevel::Debug,
+              ("  OnDestroyPresContext(), "
+               "removing TextComposition instance from the array (index=%zu)",
+               i));
+      // there should be only one composition per presContext object.
+      sTextCompositions->ElementAt(i)->Destroy();
+      sTextCompositions->RemoveElementAt(i);
+      if (sTextCompositions->IndexOf(&aPresContext) !=
+          TextCompositionArray::NoIndex) {
+        MOZ_LOG(sISMLog, LogLevel::Error,
+                ("  OnDestroyPresContext(), FAILED to remove "
+                 "TextComposition instance from the array"));
+        MOZ_CRASH("Failed to remove TextComposition instance from the array");
+      }
+    }
+  }
+
+  if (&aPresContext != sFocusedPresContext) {
+    return NS_OK;
+  }
+
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("OnDestroyPresContext(aPresContext=0x%p), "
+       "sFocusedPresContext=0x%p, sFocusedElement=0x%p, sTextCompositions=0x%p",
+       &aPresContext, sFocusedPresContext.get(), sFocusedElement.get(),
+       sTextCompositions));
+
+  DestroyIMEContentObserver();
+
+  if (sTextInputHandlingWidget) {
+    IMEState newState = GetNewIMEState(*sFocusedPresContext, nullptr);
+    InputContextAction action(InputContextAction::CAUSE_UNKNOWN,
+                              InputContextAction::LOST_FOCUS);
+    InputContext::Origin origin =
+        BrowserParent::GetFocused() ? InputContext::ORIGIN_CONTENT : sOrigin;
+    OwningNonNull<nsIWidget> textInputHandlingWidget =
+        *sTextInputHandlingWidget;
+    SetIMEState(newState, nullptr, nullptr, textInputHandlingWidget, action,
+                origin);
+  }
+  sTextInputHandlingWidget = nullptr;
+  sFocusedElement = nullptr;
+  sFocusedPresContext = nullptr;
+  return NS_OK;
+}
+
+// static
+nsresult IMEStateManager::OnRemoveContent(nsPresContext& aPresContext,
+                                          Element& aElement) {
+  // First, if there is a composition in the aElement, clean up it.
+  if (sTextCompositions) {
+    const RefPtr<TextComposition> compositionInContent =
+        sTextCompositions->GetCompositionInContent(&aPresContext, &aElement);
+
+    if (compositionInContent) {
+      MOZ_LOG(sISMLog, LogLevel::Debug,
+              ("  OnRemoveContent(), "
+               "composition is in the content"));
+
+      // Try resetting the native IME state.  Be aware, typically, this method
+      // is called during the content being removed.  Then, the native
+      // composition events which are caused by following APIs are ignored due
+      // to unsafe to run script (in PresShell::HandleEvent()).
+      nsresult rv =
+          compositionInContent->NotifyIME(REQUEST_TO_CANCEL_COMPOSITION);
+      if (NS_FAILED(rv)) {
+        compositionInContent->NotifyIME(REQUEST_TO_COMMIT_COMPOSITION);
+      }
+    }
+  }
+
+  if (!sFocusedPresContext || !sFocusedElement ||
+      !sFocusedElement->IsInclusiveDescendantOf(&aElement)) {
+    return NS_OK;
+  }
+  MOZ_ASSERT(sFocusedPresContext == &aPresContext);
+
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("OnRemoveContent(aPresContext=0x%p, aElement=0x%p), "
+       "sFocusedPresContext=0x%p, sFocusedElement=0x%p, sTextCompositions=0x%p",
+       &aPresContext, &aElement, sFocusedPresContext.get(),
+       sFocusedElement.get(), sTextCompositions));
+
+  DestroyIMEContentObserver();
+
+  // FYI: Don't clear sTextInputHandlingWidget and sFocusedPresContext because
+  // the window/document keeps having focus.
+  sFocusedElement = nullptr;
+
+  // Current IME transaction should commit
+  if (!sTextInputHandlingWidget) {
+    return NS_OK;
+  }
+
+  IMEState newState = GetNewIMEState(*sFocusedPresContext, nullptr);
+  InputContextAction action(InputContextAction::CAUSE_UNKNOWN,
+                            InputContextAction::LOST_FOCUS);
+  InputContext::Origin origin =
+      BrowserParent::GetFocused() ? InputContext::ORIGIN_CONTENT : sOrigin;
+  OwningNonNull<nsIWidget> textInputHandlingWidget = *sTextInputHandlingWidget;
+  SetIMEState(newState, &aPresContext, nullptr, textInputHandlingWidget, action,
+              origin);
+  if (sFocusedPresContext != &aPresContext || sFocusedElement) {
+    return NS_OK;  // Some body must have set focus
+  }
+
+  if (IsIMEObserverNeeded(newState)) {
+    if (RefPtr<HTMLEditor> htmlEditor =
+            nsContentUtils::GetHTMLEditor(&aPresContext)) {
+      CreateIMEContentObserver(*htmlEditor, nullptr);
+    }
+  }
+
+  return NS_OK;
+}
+
+// static
+bool IMEStateManager::CanHandleWith(const nsPresContext* aPresContext) {
+  return aPresContext && aPresContext->GetPresShell() &&
+         !aPresContext->PresShell()->IsDestroying();
+}
+
+// static
+nsresult IMEStateManager::OnChangeFocus(nsPresContext* aPresContext,
+                                        Element* aElement,
+                                        InputContextAction::Cause aCause) {
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("OnChangeFocus(aPresContext=0x%p, aElement=0x%p, aCause=%s)",
+           aPresContext, aElement, ToString(aCause).c_str()));
+
+  InputContextAction action(aCause);
+  return OnChangeFocusInternal(aPresContext, aElement, action);
+}
+
+// static
+nsresult IMEStateManager::OnChangeFocusInternal(nsPresContext* aPresContext,
+                                                Element* aElement,
+                                                InputContextAction aAction) {
+  NS_ASSERTION(!aElement || aElement->GetPresContext(
+                                Element::PresContextFor::eForComposedDoc) ==
+                                aPresContext,
+               "aPresContext does not match with one of aElement");
+
+  bool remoteHasFocus = EventStateManager::IsRemoteTarget(aElement);
+  // If we've handled focused content, we were inactive but now active,
+  // a remote process has focus, and setting focus to same content in the main
+  // process, it means that we're restoring focus without changing DOM focus
+  // both in the main process and the remote process.
+  const bool restoringContextForRemoteContent =
+      XRE_IsParentProcess() && remoteHasFocus && !sIsActive && aPresContext &&
+      sFocusedPresContext && sFocusedElement &&
+      sFocusedPresContext.get() == aPresContext &&
+      sFocusedElement.get() == aElement &&
+      aAction.mFocusChange != InputContextAction::MENU_GOT_PSEUDO_FOCUS;
+
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("OnChangeFocusInternal(aPresContext=0x%p (available: %s), "
+       "aElement=0x%p (remote: %s), aAction={ mCause=%s, "
+       "mFocusChange=%s }), sFocusedPresContext=0x%p (available: %s), "
+       "sFocusedElement=0x%p, sTextInputHandlingWidget=0x%p (available: %s), "
+       "BrowserParent::GetFocused()=0x%p, sActiveIMEContentObserver=0x%p, "
+       "sInstalledMenuKeyboardListener=%s, sIsActive=%s, "
+       "restoringContextForRemoteContent=%s",
+       aPresContext, GetBoolName(CanHandleWith(aPresContext)), aElement,
+       GetBoolName(remoteHasFocus), ToString(aAction.mCause).c_str(),
+       ToString(aAction.mFocusChange).c_str(), sFocusedPresContext.get(),
+       GetBoolName(CanHandleWith(sFocusedPresContext)), sFocusedElement.get(),
+       sTextInputHandlingWidget,
+       GetBoolName(sTextInputHandlingWidget &&
+                   !sTextInputHandlingWidget->Destroyed()),
+       BrowserParent::GetFocused(), sActiveIMEContentObserver.get(),
+       GetBoolName(sInstalledMenuKeyboardListener), GetBoolName(sIsActive),
+       GetBoolName(restoringContextForRemoteContent)));
+
+  sIsActive = !!aPresContext;
+  if (sPendingFocusedBrowserSwitchingData.isSome()) {
+    MOZ_ASSERT(XRE_IsParentProcess());
+    RefPtr<Element> focusedElement = sFocusedElement;
+    RefPtr<nsPresContext> focusedPresContext = sFocusedPresContext;
+    RefPtr<BrowserParent> browserParentBlurred =
+        sPendingFocusedBrowserSwitchingData.ref().mBrowserParentBlurred;
+    RefPtr<BrowserParent> browserParentFocused =
+        sPendingFocusedBrowserSwitchingData.ref().mBrowserParentFocused;
+    OnFocusMovedBetweenBrowsers(browserParentBlurred, browserParentFocused);
+    // If another call of this method happens during the
+    // OnFocusMovedBetweenBrowsers call, we shouldn't take back focus to
+    // the old one.
+    if (focusedElement != sFocusedElement.get() ||
+        focusedPresContext != sFocusedPresContext.get()) {
+      MOZ_LOG(sISMLog, LogLevel::Debug,
+              ("  OnChangeFocusInternal(aPresContext=0x%p, aElement=0x%p) "
+               "stoped handling it because the focused content was changed to "
+               "sFocusedPresContext=0x%p, sFocusedElement=0x%p by another call",
+               aPresContext, aElement, sFocusedPresContext.get(),
+               sFocusedElement.get()));
+      return NS_OK;
+    }
+  }
+
+  // If new aPresShell has been destroyed, this should handle the focus change
+  // as nobody is getting focus.
+  MOZ_ASSERT_IF(!aPresContext, !aElement);
+  if (NS_WARN_IF(aPresContext && !CanHandleWith(aPresContext))) {
+    MOZ_LOG(sISMLog, LogLevel::Warning,
+            ("  OnChangeFocusInternal(), called with destroyed PresShell, "
+             "handling this call as nobody getting focus"));
+    aPresContext = nullptr;
+    aElement = nullptr;
+  } else if (!aPresContext) {
+    aElement = nullptr;
+  }
+
+  const nsCOMPtr<nsIWidget> oldWidget = sTextInputHandlingWidget;
+  const nsCOMPtr<nsIWidget> newWidget =
+      aPresContext ? aPresContext->GetTextInputHandlingWidget() : nullptr;
+  const bool focusActuallyChanging =
+      (sFocusedElement != aElement || sFocusedPresContext != aPresContext ||
+       oldWidget != newWidget ||
+       (remoteHasFocus && !restoringContextForRemoteContent &&
+        (aAction.mFocusChange != InputContextAction::MENU_GOT_PSEUDO_FOCUS)));
+
+  // If old widget has composition, we may need to commit composition since
+  // a native IME context is shared on all editors on some widgets or all
+  // widgets (it depends on platforms).
+  if (oldWidget && focusActuallyChanging && sTextCompositions) {
+    RefPtr<TextComposition> composition =
+        sTextCompositions->GetCompositionFor(oldWidget);
+    if (composition) {
+      // However, don't commit the composition if we're being inactivated
+      // but the composition should be kept even during deactive.
+      // Note that oldWidget and sFocusedIMEWidget may be different here (in
+      // such case, sFocusedIMEWidget is perhaps nullptr).  For example, IME
+      // may receive only blur notification but still has composition.
+      // We need to clean up only the oldWidget's composition state here.
+      if (aPresContext ||
+          !oldWidget->IMENotificationRequestsRef().WantDuringDeactive()) {
+        MOZ_LOG(
+            sISMLog, LogLevel::Info,
+            ("  OnChangeFocusInternal(), requesting to commit composition to "
+             "the (previous) focused widget"));
+        NotifyIME(REQUEST_TO_COMMIT_COMPOSITION, oldWidget,
+                  composition->GetBrowserParent());
+      }
+    }
+  }
+
+  if (sActiveIMEContentObserver) {
+    MOZ_ASSERT(!remoteHasFocus || XRE_IsContentProcess(),
+               "IMEContentObserver should have been destroyed by "
+               "OnFocusMovedBetweenBrowsers.");
+    if (!aPresContext) {
+      if (!sActiveIMEContentObserver->KeepAliveDuringDeactive()) {
+        DestroyIMEContentObserver();
+      }
+    }
+    // Otherwise, i.e., new focused content is in this process, let's check
+    // whether the new focused content is already being managed by the
+    // active IME content observer.
+    else if (!sActiveIMEContentObserver->IsManaging(*aPresContext, aElement)) {
+      DestroyIMEContentObserver();
+    }
+  }
+
+  if (!aPresContext) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnChangeFocusInternal(), no nsPresContext is being activated"));
+    return NS_OK;
+  }
+
+  if (NS_WARN_IF(!newWidget)) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  OnChangeFocusInternal(), FAILED due to no widget to manage its "
+             "IME state"));
+    return NS_OK;
+  }
+
+  // Update the cached widget since root view of the presContext may be
+  // changed to different view.
+  sTextInputHandlingWidget = newWidget;
+
+  // If a child process has focus, we should disable IME state until the child
+  // process actually gets focus because if user types keys before that they
+  // are handled by IME.
+  IMEState newState = remoteHasFocus ? IMEState(IMEEnabled::Disabled)
+                                     : GetNewIMEState(*aPresContext, aElement);
+  bool setIMEState = true;
+
+  if (remoteHasFocus && XRE_IsParentProcess()) {
+    if (aAction.mFocusChange == InputContextAction::MENU_GOT_PSEUDO_FOCUS) {
+      // If menu keyboard listener is installed, we need to disable IME now.
+      setIMEState = true;
+    } else if (aAction.mFocusChange ==
+               InputContextAction::MENU_LOST_PSEUDO_FOCUS) {
+      // If menu keyboard listener is uninstalled, we need to restore
+      // input context which was set by the remote process.  However, if
+      // the remote process hasn't been set input context yet, we need to
+      // wait next SetInputContextForChildProcess() call.
+      if (HasActiveChildSetInputContext()) {
+        setIMEState = true;
+        newState = sActiveChildInputContext.mIMEState;
+      } else {
+        setIMEState = false;
+      }
+    } else if (focusActuallyChanging) {
+      InputContext context = newWidget->GetInputContext();
+      if (context.mIMEState.mEnabled == IMEEnabled::Disabled &&
+          context.mOrigin == InputContext::ORIGIN_CONTENT) {
+        setIMEState = false;
+        MOZ_LOG(sISMLog, LogLevel::Debug,
+                ("  OnChangeFocusInternal(), doesn't set IME state because "
+                 "focused element (or document) is in a child process and the "
+                 "IME state is already disabled by a remote process"));
+      } else {
+        // When new remote process gets focus, we should forget input context
+        // coming from old focused remote process.
+        ResetActiveChildInputContext();
+        MOZ_LOG(sISMLog, LogLevel::Debug,
+                ("  OnChangeFocusInternal(), will disable IME until new "
+                 "focused element (or document) in the child process will get "
+                 "focus actually"));
+      }
+    } else if (newWidget->GetInputContext().mOrigin !=
+               InputContext::ORIGIN_MAIN) {
+      // When focus is NOT changed actually, we shouldn't set IME state if
+      // current input context was set by a remote process since that means
+      // that the window is being activated and the child process may have
+      // composition.  Then, we shouldn't commit the composition with making
+      // IME state disabled.
+      setIMEState = false;
+      MOZ_LOG(
+          sISMLog, LogLevel::Debug,
+          ("  OnChangeFocusInternal(), doesn't set IME state because focused "
+           "element (or document) is already in the child process"));
+    }
+  } else {
+    // When this process gets focus, we should forget input context coming
+    // from remote process.
+    ResetActiveChildInputContext();
+  }
+
+  if (setIMEState) {
+    if (!focusActuallyChanging) {
+      // actual focus isn't changing, but if IME enabled state is changing,
+      // we should do it.
+      InputContext context = newWidget->GetInputContext();
+      if (context.mIMEState.mEnabled == newState.mEnabled) {
+        MOZ_LOG(sISMLog, LogLevel::Debug,
+                ("  OnChangeFocusInternal(), neither focus nor IME state is "
+                 "changing"));
+        return NS_OK;
+      }
+      aAction.mFocusChange = InputContextAction::FOCUS_NOT_CHANGED;
+
+      // Even if focus isn't changing actually, we should commit current
+      // composition here since the IME state is changing.
+      if (sFocusedPresContext && oldWidget && !focusActuallyChanging) {
+        NotifyIME(REQUEST_TO_COMMIT_COMPOSITION, oldWidget,
+                  sFocusedIMEBrowserParent);
+      }
+    } else if (aAction.mFocusChange == InputContextAction::FOCUS_NOT_CHANGED) {
+      // If aElement isn't null or aElement is null but editable, somebody gets
+      // focus.
+      bool gotFocus = aElement || (newState.mEnabled == IMEEnabled::Enabled);
+      aAction.mFocusChange = gotFocus ? InputContextAction::GOT_FOCUS
+                                      : InputContextAction::LOST_FOCUS;
+    }
+
+    if (remoteHasFocus && HasActiveChildSetInputContext() &&
+        aAction.mFocusChange == InputContextAction::MENU_LOST_PSEUDO_FOCUS) {
+      // Restore the input context in the active remote process when
+      // menu keyboard listener is uninstalled and active remote tab has
+      // focus.
+      SetInputContext(*newWidget, sActiveChildInputContext, aAction);
+    } else {
+      // Update IME state for new focus widget
+      SetIMEState(newState, aPresContext, aElement, *newWidget, aAction,
+                  remoteHasFocus ? InputContext::ORIGIN_CONTENT : sOrigin);
+    }
+  }
+
+  sFocusedPresContext = aPresContext;
+  sFocusedElement = aElement;
+
+  // Don't call CreateIMEContentObserver() here  because it will be called from
+  // the focus event handler of focused editor.
+
+  MOZ_LOG(sISMLog, LogLevel::Debug,
+          ("  OnChangeFocusInternal(), modified IME state for "
+           "sFocusedPresContext=0x%p, sFocusedElement=0x%p",
+           sFocusedPresContext.get(), sFocusedElement.get()));
+
+  return NS_OK;
+}
+
+// static
+void IMEStateManager::OnInstalledMenuKeyboardListener(bool aInstalling) {
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("OnInstalledMenuKeyboardListener(aInstalling=%s), "
+       "sInstalledMenuKeyboardListener=%s, BrowserParent::GetFocused()=0x%p, "
+       "sActiveChildInputContext=%s",
+       GetBoolName(aInstalling), GetBoolName(sInstalledMenuKeyboardListener),
+       BrowserParent::GetFocused(),
+       ToString(sActiveChildInputContext).c_str()));
+
+  sInstalledMenuKeyboardListener = aInstalling;
+
+  InputContextAction action(InputContextAction::CAUSE_UNKNOWN,
+                            aInstalling
+                                ? InputContextAction::MENU_GOT_PSEUDO_FOCUS
+                                : InputContextAction::MENU_LOST_PSEUDO_FOCUS);
+  RefPtr<nsPresContext> focusedPresContext = sFocusedPresContext;
+  RefPtr<Element> focusedElement = sFocusedElement;
+  OnChangeFocusInternal(focusedPresContext, focusedElement, action);
+}
+
+// static
+bool IMEStateManager::OnMouseButtonEventInEditor(
+    nsPresContext& aPresContext, Element* aElement,
+    WidgetMouseEvent& aMouseEvent) {
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("OnMouseButtonEventInEditor(aPresContext=0x%p (available: %s), "
+           "aElement=0x%p, aMouseEvent=0x%p), sFocusedPresContext=0x%p, "
+           "sFocusedElement=0x%p",
+           &aPresContext, GetBoolName(CanHandleWith(&aPresContext)), aElement,
+           &aMouseEvent, sFocusedPresContext.get(), sFocusedElement.get()));
+
+  if (sFocusedPresContext != &aPresContext || sFocusedElement != aElement) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnMouseButtonEventInEditor(), "
+             "the mouse event isn't fired on the editor managed by ISM"));
+    return false;
+  }
+
+  if (!sActiveIMEContentObserver) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnMouseButtonEventInEditor(), "
+             "there is no active IMEContentObserver"));
+    return false;
+  }
+
+  if (!sActiveIMEContentObserver->IsManaging(aPresContext, aElement)) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnMouseButtonEventInEditor(), "
+             "the active IMEContentObserver isn't managing the editor"));
+    return false;
+  }
+
+  OwningNonNull<IMEContentObserver> observer = *sActiveIMEContentObserver;
+  bool consumed = observer->OnMouseButtonEvent(aPresContext, aMouseEvent);
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("  OnMouseButtonEventInEditor(), "
+           "mouse event (mMessage=%s, mButton=%d) is %s",
+           ToChar(aMouseEvent.mMessage), aMouseEvent.mButton,
+           consumed ? "consumed" : "not consumed"));
+  return consumed;
+}
+
+// static
+void IMEStateManager::OnClickInEditor(nsPresContext& aPresContext,
+                                      Element* aElement,
+                                      const WidgetMouseEvent& aMouseEvent) {
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("OnClickInEditor(aPresContext=0x%p (available: %s), aElement=0x%p, "
+           "aMouseEvent=0x%p), sFocusedPresContext=0x%p, sFocusedElement=0x%p, "
+           "sTextInputHandlingWidget=0x%p (available: %s)",
+           &aPresContext, GetBoolName(CanHandleWith(&aPresContext)), aElement,
+           &aMouseEvent, sFocusedPresContext.get(), sFocusedElement.get(),
+           sTextInputHandlingWidget,
+           GetBoolName(sTextInputHandlingWidget &&
+                       !sTextInputHandlingWidget->Destroyed())));
+
+  if (sFocusedPresContext != &aPresContext || sFocusedElement != aElement ||
+      NS_WARN_IF(!sFocusedPresContext) ||
+      NS_WARN_IF(!sTextInputHandlingWidget) ||
+      NS_WARN_IF(sTextInputHandlingWidget->Destroyed())) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnClickInEditor(), "
+             "the mouse event isn't fired on the editor managed by ISM"));
+    return;
+  }
+
+  const OwningNonNull<nsIWidget> textInputHandlingWidget =
+      *sTextInputHandlingWidget;
+
+#ifdef DEBUG
+  {
+    nsCOMPtr<nsIWidget> currentTextInputHandlingWidget =
+        sFocusedPresContext->GetTextInputHandlingWidget();
+    MOZ_ASSERT(!currentTextInputHandlingWidget ||
+               currentTextInputHandlingWidget == textInputHandlingWidget);
+  }
+#endif  // DEBUG
+
+  if (!aMouseEvent.IsTrusted()) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnClickInEditor(), "
+             "the mouse event isn't a trusted event"));
+    return;  // ignore untrusted event.
+  }
+
+  if (aMouseEvent.mButton) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnClickInEditor(), "
+             "the mouse event isn't a left mouse button event"));
+    return;  // not a left click event.
+  }
+
+  if (aMouseEvent.mClickCount != 1) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnClickInEditor(), "
+             "the mouse event isn't a single click event"));
+    return;  // should notify only first click event.
+  }
+
+  MOZ_ASSERT_IF(aElement, !EventStateManager::IsRemoteTarget(aElement));
+  InputContextAction::Cause cause =
+      aMouseEvent.mInputSource == MouseEvent_Binding::MOZ_SOURCE_TOUCH
+          ? InputContextAction::CAUSE_TOUCH
+          : InputContextAction::CAUSE_MOUSE;
+
+  InputContextAction action(cause, InputContextAction::FOCUS_NOT_CHANGED);
+  IMEState newState = GetNewIMEState(aPresContext, aElement);
+  // If the state is not editable, there should be no active IMEContentObserver.
+  // However, if this click sets focus to the editor, IMEContentObserver may
+  // have not been created yet.  Instead, if there is active IMEContentObserver,
+  // it should be editable.
+  MOZ_ASSERT_IF(!newState.IsEditable(), !sActiveIMEContentObserver);
+  MOZ_ASSERT_IF(sActiveIMEContentObserver, newState.IsEditable());
+  SetIMEState(newState, &aPresContext, aElement, textInputHandlingWidget,
+              action, sOrigin);
+}
+
+// static
+Element* IMEStateManager::GetFocusedElement() { return sFocusedElement; }
+
+// static
+bool IMEStateManager::IsFocusedElement(const nsPresContext& aPresContext,
+                                       const Element* aFocusedElement) {
+  if (!sFocusedPresContext || &aPresContext != sFocusedPresContext) {
+    return false;
+  }
+
+  if (sFocusedElement == aFocusedElement) {
+    return true;
+  }
+
+  // If sFocusedElement is not nullptr, but aFocusedElement is nullptr, it does
+  // not have focus from point of view of IMEStateManager.
+  if (sFocusedElement) {
+    return false;
+  }
+
+  // If the caller does not think that nobody has focus, but we know there is
+  // a focused content, the caller must be called with wrong content.
+  if (!aFocusedElement) {
+    return false;
+  }
+
+  // If the aFocusedElement is in design mode, sFocusedElement may be nullptr.
+  if (aFocusedElement->IsInDesignMode()) {
+    MOZ_ASSERT(&aPresContext == sFocusedPresContext && !sFocusedElement);
+    return true;
+  }
+
+  // Otherwise, only when aFocusedElement is the root element, it can have
+  // focus, but IMEStateManager::OnChangeFocus is called with nullptr for
+  // aFocusedElement if it was not editable.
+  // XXX In this case, should the caller update sFocusedElement?
+  return aFocusedElement->IsEditable() && sFocusedPresContext->Document() &&
+         sFocusedPresContext->Document()->GetRootElement() == aFocusedElement;
+}
+
+// static
+void IMEStateManager::OnFocusInEditor(nsPresContext& aPresContext,
+                                      Element* aElement,
+                                      EditorBase& aEditorBase) {
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("OnFocusInEditor(aPresContext=0x%p (available: %s), aElement=0x%p, "
+           "aEditorBase=0x%p), sFocusedPresContext=0x%p, sFocusedElement=0x%p, "
+           "sActiveIMEContentObserver=0x%p",
+           &aPresContext, GetBoolName(CanHandleWith(&aPresContext)), aElement,
+           &aEditorBase, sFocusedPresContext.get(), sFocusedElement.get(),
+           sActiveIMEContentObserver.get()));
+
+  if (!IsFocusedElement(aPresContext, aElement)) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnFocusInEditor(), "
+             "an editor not managed by ISM gets focus"));
+    return;
+  }
+  MOZ_ASSERT(sTextInputHandlingWidget);
+
+  // If the IMEContentObserver instance isn't managing the editor actually,
+  // we need to recreate the instance.
+  if (sActiveIMEContentObserver) {
+    if (sActiveIMEContentObserver->IsManaging(aPresContext, aElement)) {
+      MOZ_LOG(
+          sISMLog, LogLevel::Debug,
+          ("  OnFocusInEditor(), "
+           "the editor is already being managed by sActiveIMEContentObserver"));
+      return;
+    }
+    // If the IMEContentObserver has not finished initializing itself yet,
+    // we don't need to recreate it because the following
+    // TryToFlushPendingNotifications call must make it initialized.
+    const nsCOMPtr<nsIWidget> textInputHandlingWidget =
+        sTextInputHandlingWidget;
+    if (!sActiveIMEContentObserver->IsBeingInitializedFor(aPresContext,
+                                                          aElement)) {
+      DestroyIMEContentObserver();
+    }
+    if (NS_WARN_IF(!IsFocusedElement(aPresContext, aElement)) ||
+        NS_WARN_IF(!sTextInputHandlingWidget) ||
+        NS_WARN_IF(sTextInputHandlingWidget != textInputHandlingWidget)) {
+      MOZ_LOG(sISMLog, LogLevel::Error,
+              ("  OnFocusInEditor(), detected unexpected focus change with "
+               "re-initializing active IMEContentObserver"));
+      return;
+    }
+  }
+
+  if (!sActiveIMEContentObserver && sTextInputHandlingWidget &&
+      IsIMEObserverNeeded(
+          sTextInputHandlingWidget->GetInputContext().mIMEState)) {
+    CreateIMEContentObserver(aEditorBase, aElement);
+    if (sActiveIMEContentObserver) {
+      MOZ_LOG(sISMLog, LogLevel::Debug,
+              ("  OnFocusInEditor(), new IMEContentObserver is created (0x%p)",
+               sActiveIMEContentObserver.get()));
+    }
+  }
+
+  if (sActiveIMEContentObserver) {
+    sActiveIMEContentObserver->TryToFlushPendingNotifications(false);
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnFocusInEditor(), trying to send pending notifications in "
+             "the active IMEContentObserver (0x%p)...",
+             sActiveIMEContentObserver.get()));
+  }
+}
+
+// static
+void IMEStateManager::OnEditorInitialized(EditorBase& aEditorBase) {
+  if (!sActiveIMEContentObserver ||
+      !sActiveIMEContentObserver->WasInitializedWith(aEditorBase)) {
+    return;
+  }
+
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("OnEditorInitialized(aEditorBase=0x%p)", &aEditorBase));
+
+  sActiveIMEContentObserver->UnsuppressNotifyingIME();
+}
+
+// static
+void IMEStateManager::OnEditorDestroying(EditorBase& aEditorBase) {
+  if (!sActiveIMEContentObserver ||
+      !sActiveIMEContentObserver->WasInitializedWith(aEditorBase)) {
+    return;
+  }
+
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("OnEditorDestroying(aEditorBase=0x%p)", &aEditorBase));
+
+  // The IMEContentObserver shouldn't notify IME of anything until reframing
+  // is finished.
+  sActiveIMEContentObserver->SuppressNotifyingIME();
+}
+
+void IMEStateManager::OnReFocus(nsPresContext& aPresContext,
+                                Element& aElement) {
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("OnReFocus(aPresContext=0x%p (available: %s), aElement=0x%p), "
+           "sActiveIMEContentObserver=0x%p, aElement=0x%p",
+           &aPresContext, GetBoolName(CanHandleWith(&aPresContext)), &aElement,
+           sActiveIMEContentObserver.get(), sFocusedElement.get()));
+
+  if (NS_WARN_IF(!sTextInputHandlingWidget) ||
+      NS_WARN_IF(sTextInputHandlingWidget->Destroyed())) {
+    return;
+  }
+
+  if (!sActiveIMEContentObserver ||
+      !sActiveIMEContentObserver->IsManaging(aPresContext, &aElement)) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  OnReFocus(), there is no valid IMEContentObserver, so we don't "
+             "manage this. Ignore this"));
+    return;
+  }
+
+  MOZ_ASSERT(&aElement == sFocusedElement.get());
+
+  if (!UserActivation::IsHandlingUserInput() ||
+      UserActivation::IsHandlingKeyboardInput()) {
+    return;
+  }
+
+  const OwningNonNull<nsIWidget> textInputHandlingWidget =
+      *sTextInputHandlingWidget;
+
+  // Don't update IME state during composition.
+  if (sTextCompositions) {
+    if (const TextComposition* composition =
+            sTextCompositions->GetCompositionFor(textInputHandlingWidget)) {
+      if (composition->IsComposing()) {
+        return;
+      }
+    }
+  }
+
+  InputContextAction action(InputContextAction::CAUSE_UNKNOWN,
+                            InputContextAction::FOCUS_NOT_CHANGED);
+  IMEState newState = GetNewIMEState(aPresContext, &aElement);
+  MOZ_ASSERT(newState.IsEditable());
+  SetIMEState(newState, &aPresContext, &aElement, textInputHandlingWidget,
+              action, sOrigin);
+}
+
+// static
+void IMEStateManager::MaybeOnEditableStateDisabled(nsPresContext& aPresContext,
+                                                   dom::Element* aElement) {
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("MaybeOnEditableStateDisabled(aPresContext=0x%p, aElement=0x%p), "
+       "sFocusedPresContext=0x%p (available: %s), "
+       "sFocusedElement=0x%p, sTextInputHandlingWidget=0x%p (available: %s), "
+       "sActiveIMEContentObserver=0x%p, sIsGettingNewIMEState=%s",
+       &aPresContext, aElement, sFocusedPresContext.get(),
+       GetBoolName(CanHandleWith(sFocusedPresContext)), sFocusedElement.get(),
+       sTextInputHandlingWidget,
+       GetBoolName(sTextInputHandlingWidget &&
+                   !sTextInputHandlingWidget->Destroyed()),
+       sActiveIMEContentObserver.get(), GetBoolName(sIsGettingNewIMEState)));
+
+  if (sIsGettingNewIMEState) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  MaybeOnEditableStateDisabled(), "
+             "does nothing because of called while getting new IME state"));
+    return;
+  }
+
+  if (&aPresContext != sFocusedPresContext || aElement != sFocusedElement) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  MaybeOnEditableStateDisabled(), "
+             "does nothing because of another element already has focus"));
+    return;
+  }
+
+  if (NS_WARN_IF(!sTextInputHandlingWidget) ||
+      NS_WARN_IF(sTextInputHandlingWidget->Destroyed())) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  MaybeOnEditableStateDisabled(), FAILED due to "
+             "the widget for the managing the nsPresContext has gone"));
+    return;
+  }
+
+  const OwningNonNull<nsIWidget> textInputHandlingWidget =
+      *sTextInputHandlingWidget;
+
+#ifdef DEBUG
+  {
+    nsCOMPtr<nsIWidget> currentTextInputHandlingWidget =
+        aPresContext.GetTextInputHandlingWidget();
+    MOZ_ASSERT(!currentTextInputHandlingWidget ||
+               currentTextInputHandlingWidget == textInputHandlingWidget);
+  }
+#endif  // DEBUG
+
+  const IMEState newIMEState = GetNewIMEState(aPresContext, aElement);
+  // If IME state becomes editable, HTMLEditor should also be initialized with
+  // same path as it gets focus.  Therefore, IMEStateManager::UpdateIMEState
+  // should be called by HTMLEditor instead.
+  if (newIMEState.IsEditable()) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  MaybeOnEditableStateDisabled(), "
+             "does nothing because IME state does not become disabled"));
+    return;
+  }
+
+  // Otherwise, disable IME on the widget and destroy active IMEContentObserver
+  // if there is.
+  const InputContext inputContext = textInputHandlingWidget->GetInputContext();
+  if (inputContext.mIMEState.mEnabled == newIMEState.mEnabled) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  MaybeOnEditableStateDisabled(), "
+             "does nothing because IME state is not changed"));
+    return;
+  }
+
+  if (sActiveIMEContentObserver) {
+    DestroyIMEContentObserver();
+  }
+
+  InputContextAction action(InputContextAction::CAUSE_UNKNOWN,
+                            InputContextAction::FOCUS_NOT_CHANGED);
+  SetIMEState(newIMEState, &aPresContext, aElement, textInputHandlingWidget,
+              action, sOrigin);
+}
+
+// static
+void IMEStateManager::UpdateIMEState(const IMEState& aNewIMEState,
+                                     Element* aElement, EditorBase& aEditorBase,
+                                     const UpdateIMEStateOptions& aOptions) {
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("UpdateIMEState(aNewIMEState=%s, aElement=0x%p, aEditorBase=0x%p, "
+       "aOptions=0x%0x), sFocusedPresContext=0x%p (available: %s), "
+       "sFocusedElement=0x%p, sTextInputHandlingWidget=0x%p (available: %s), "
+       "sActiveIMEContentObserver=0x%p, sIsGettingNewIMEState=%s",
+       ToString(aNewIMEState).c_str(), aElement, &aEditorBase,
+       aOptions.serialize(), sFocusedPresContext.get(),
+       GetBoolName(CanHandleWith(sFocusedPresContext)), sFocusedElement.get(),
+       sTextInputHandlingWidget,
+       GetBoolName(sTextInputHandlingWidget &&
+                   !sTextInputHandlingWidget->Destroyed()),
+       sActiveIMEContentObserver.get(), GetBoolName(sIsGettingNewIMEState)));
+
+  if (sIsGettingNewIMEState) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  UpdateIMEState(), "
+             "does nothing because of called while getting new IME state"));
+    return;
+  }
+
+  RefPtr<PresShell> presShell(aEditorBase.GetPresShell());
+  if (NS_WARN_IF(!presShell)) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  UpdateIMEState(), FAILED due to "
+             "editor doesn't have PresShell"));
+    return;
+  }
+
+  const RefPtr<nsPresContext> presContext =
+      aElement
+          ? aElement->GetPresContext(Element::PresContextFor::eForComposedDoc)
+          : aEditorBase.GetPresContext();
+  if (NS_WARN_IF(!presContext)) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  UpdateIMEState(), FAILED due to "
+             "editor doesn't have PresContext"));
+    return;
+  }
+
+  // IMEStateManager::UpdateIMEState() should be called after
+  // IMEStateManager::OnChangeFocus() is called for setting focus to aElement
+  // and aEditorBase.  However, when aEditorBase is an HTMLEditor, this may be
+  // called by nsIEditor::PostCreate() before IMEStateManager::OnChangeFocus().
+  // Similarly, when aEditorBase is a TextEditor, this may be called by
+  // nsIEditor::SetFlags().  In such cases, this method should do nothing
+  // because input context should be updated when
+  // IMEStateManager::OnChangeFocus() is called later.
+  if (sFocusedPresContext != presContext) {
+    MOZ_LOG(sISMLog, LogLevel::Warning,
+            ("  UpdateIMEState(), does nothing due to "
+             "the editor hasn't managed by IMEStateManager yet"));
+    return;
+  }
+
+  // If IMEStateManager doesn't manage any document, this cannot update IME
+  // state of any widget.
+  if (NS_WARN_IF(!sFocusedPresContext)) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  UpdateIMEState(), FAILED due to "
+             "no managing nsPresContext"));
+    return;
+  }
+
+  if (NS_WARN_IF(!sTextInputHandlingWidget) ||
+      NS_WARN_IF(sTextInputHandlingWidget->Destroyed())) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  UpdateIMEState(), FAILED due to "
+             "the widget for the managing nsPresContext has gone"));
+    return;
+  }
+
+  const OwningNonNull<nsIWidget> textInputHandlingWidget =
+      *sTextInputHandlingWidget;
+
+#ifdef DEBUG
+  {
+    nsCOMPtr<nsIWidget> currentTextInputHandlingWidget =
+        sFocusedPresContext->GetTextInputHandlingWidget();
+    MOZ_ASSERT(!currentTextInputHandlingWidget ||
+               currentTextInputHandlingWidget == textInputHandlingWidget);
+  }
+#endif  // DEBUG
+
+  // TODO: Investigate if we could put off to initialize IMEContentObserver
+  //       later because a lot of callers need to be marked as
+  //       MOZ_CAN_RUN_SCRIPT otherwise.
+
+  // Even if there is active IMEContentObserver, it may not be observing the
+  // editor with current editable root content due to reframed.  In such case,
+  // We should try to reinitialize the IMEContentObserver.
+  if (sActiveIMEContentObserver && IsIMEObserverNeeded(aNewIMEState)) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  UpdateIMEState(), try to reinitialize the "
+             "active IMEContentObserver"));
+    OwningNonNull<IMEContentObserver> contentObserver =
+        *sActiveIMEContentObserver;
+    OwningNonNull<nsPresContext> presContext = *sFocusedPresContext;
+    if (!contentObserver->MaybeReinitialize(
+            textInputHandlingWidget, presContext, aElement, aEditorBase)) {
+      MOZ_LOG(sISMLog, LogLevel::Error,
+              ("  UpdateIMEState(), failed to reinitialize the "
+               "active IMEContentObserver"));
+    }
+    if (NS_WARN_IF(textInputHandlingWidget->Destroyed())) {
+      MOZ_LOG(sISMLog, LogLevel::Error,
+              ("  UpdateIMEState(), widget has gone during re-initializing the "
+               "active IMEContentObserver"));
+      return;
+    }
+  }
+
+  // If there is no active IMEContentObserver or it isn't observing the
+  // editor correctly, we should recreate it.
+  const bool createTextStateManager =
+      IsIMEObserverNeeded(aNewIMEState) &&
+      (!sActiveIMEContentObserver ||
+       !sActiveIMEContentObserver->IsManaging(*sFocusedPresContext, aElement));
+  // If we're recreating new IMEContentObserver or new state does not need
+  // IMEContentObserver, destroy the active IMEContentObserver.
+  const bool destroyTextStateManager =
+      sActiveIMEContentObserver &&
+      (createTextStateManager || !IsIMEObserverNeeded(aNewIMEState));
+
+  const bool updateIMEState =
+      aOptions.contains(UpdateIMEStateOption::ForceUpdate) ||
+      (textInputHandlingWidget->GetInputContext().mIMEState.mEnabled !=
+       aNewIMEState.mEnabled);
+  if (NS_WARN_IF(textInputHandlingWidget->Destroyed())) {
+    MOZ_LOG(
+        sISMLog, LogLevel::Error,
+        ("  UpdateIMEState(), widget has gone during getting input context"));
+    return;
+  }
+
+  if (updateIMEState &&
+      !aOptions.contains(UpdateIMEStateOption::DontCommitComposition)) {
+    // commit current composition before modifying IME state.
+    NotifyIME(REQUEST_TO_COMMIT_COMPOSITION, textInputHandlingWidget,
+              sFocusedIMEBrowserParent);
+    if (NS_WARN_IF(textInputHandlingWidget->Destroyed())) {
+      MOZ_LOG(sISMLog, LogLevel::Error,
+              ("  UpdateIMEState(), widget has gone during committing "
+               "composition"));
+      return;
+    }
+    // FIXME: If committing composition changes IME state recursively, we should
+    //        not keep updating IME state here.  However, how can we manage it?
+    //        Is a generation of the state is required?
+  }
+
+  if (destroyTextStateManager) {
+    DestroyIMEContentObserver();
+    if (NS_WARN_IF(textInputHandlingWidget->Destroyed()) ||
+        NS_WARN_IF(sTextInputHandlingWidget != textInputHandlingWidget)) {
+      MOZ_LOG(sISMLog, LogLevel::Error,
+              ("  UpdateIMEState(), has set input context, but the widget is "
+               "not focused"));
+      return;
+    }
+  }
+
+  if (updateIMEState) {
+    InputContextAction action(InputContextAction::CAUSE_UNKNOWN,
+                              InputContextAction::FOCUS_NOT_CHANGED);
+    RefPtr<nsPresContext> editorPresContext = aEditorBase.GetPresContext();
+    if (NS_WARN_IF(!editorPresContext)) {
+      MOZ_LOG(sISMLog, LogLevel::Error,
+              ("  UpdateIMEState(), nsPresContext for editor has already been "
+               "lost"));
+      return;
+    }
+    SetIMEState(aNewIMEState, editorPresContext, aElement,
+                textInputHandlingWidget, action, sOrigin);
+    if (NS_WARN_IF(textInputHandlingWidget->Destroyed()) ||
+        NS_WARN_IF(sTextInputHandlingWidget != textInputHandlingWidget)) {
+      MOZ_LOG(sISMLog, LogLevel::Error,
+              ("  UpdateIMEState(), has set input context, but the widget is "
+               "not focused"));
+      return;
+    }
+    if (NS_WARN_IF(
+            sTextInputHandlingWidget->GetInputContext().mIMEState.mEnabled !=
+            aNewIMEState.mEnabled)) {
+      MOZ_LOG(sISMLog, LogLevel::Error,
+              ("  UpdateIMEState(), has set input context, but IME enabled "
+               "state was overridden by somebody else"));
+      return;
+    }
+  }
+
+  NS_ASSERTION(IsFocusedElement(*presContext, aElement),
+               "aElement does not match with sFocusedElement");
+
+  if (createTextStateManager) {
+    if (!sActiveIMEContentObserver && sFocusedPresContext &&
+        sTextInputHandlingWidget) {
+      // XXX In this case, it might not be enough safe to notify IME of
+      //     anything.  So, don't try to flush pending notifications of
+      //     IMEContentObserver here.
+      CreateIMEContentObserver(aEditorBase, aElement);
+    } else {
+      MOZ_LOG(sISMLog, LogLevel::Error,
+              ("  UpdateIMEState(), wanted to create IMEContentObserver, but "
+               "lost focus"));
+    }
+  }
+}
+
+// static
+IMEState IMEStateManager::GetNewIMEState(const nsPresContext& aPresContext,
+                                         Element* aElement) {
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("GetNewIMEState(aPresContext=0x%p, aElement=0x%p), "
+       "sInstalledMenuKeyboardListener=%s",
+       &aPresContext, aElement, GetBoolName(sInstalledMenuKeyboardListener)));
+
+  if (!CanHandleWith(&aPresContext)) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  GetNewIMEState() returns IMEEnabled::Disabled because "
+             "the nsPresContext has been destroyed"));
+    return IMEState(IMEEnabled::Disabled);
+  }
+
+  // On Printing or Print Preview, we don't need IME.
+  if (aPresContext.Type() == nsPresContext::eContext_PrintPreview ||
+      aPresContext.Type() == nsPresContext::eContext_Print) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  GetNewIMEState() returns IMEEnabled::Disabled because "
+             "the nsPresContext is for print or print preview"));
+    return IMEState(IMEEnabled::Disabled);
+  }
+
+  if (sInstalledMenuKeyboardListener) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  GetNewIMEState() returns IMEEnabled::Disabled because "
+             "menu keyboard listener was installed"));
+    return IMEState(IMEEnabled::Disabled);
+  }
+
+  if (!aElement) {
+    // Even if there are no focused content, the focused document might be
+    // editable, such case is design mode.
+    if (aPresContext.Document() && aPresContext.Document()->IsInDesignMode()) {
+      MOZ_LOG(sISMLog, LogLevel::Debug,
+              ("  GetNewIMEState() returns IMEEnabled::Enabled because "
+               "design mode editor has focus"));
+      return IMEState(IMEEnabled::Enabled);
+    }
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  GetNewIMEState() returns IMEEnabled::Disabled because "
+             "no content has focus"));
+    return IMEState(IMEEnabled::Disabled);
+  }
+
+  // If aElement is in designMode, aElement should be the root node of the
+  // document.
+  if (aElement && aElement->IsInDesignMode()) {
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  GetNewIMEState() returns IMEEnabled::Enabled because "
+             "a content node in design mode editor has focus"));
+    return IMEState(IMEEnabled::Enabled);
+  }
+
+  // nsIContent::GetDesiredIMEState() may cause a call of UpdateIMEState()
+  // from EditorBase::PostCreate() because GetDesiredIMEState() needs to
+  // retrieve an editor instance for the element if it's editable element.
+  // For avoiding such nested IME state updates, we should set
+  // sIsGettingNewIMEState here and UpdateIMEState() should check it.
+  GettingNewIMEStateBlocker blocker;
+
+  IMEState newIMEState = aElement->GetDesiredIMEState();
+  MOZ_LOG(sISMLog, LogLevel::Debug,
+          ("  GetNewIMEState() returns %s", ToString(newIMEState).c_str()));
+  return newIMEState;
+}
+
+// static
+void IMEStateManager::ResetActiveChildInputContext() {
+  sActiveChildInputContext.mIMEState.mEnabled = IMEEnabled::Unknown;
+}
+
+// static
+bool IMEStateManager::HasActiveChildSetInputContext() {
+  return sActiveChildInputContext.mIMEState.mEnabled != IMEEnabled::Unknown;
+}
+
+// static
+void IMEStateManager::SetInputContextForChildProcess(
+    BrowserParent* aBrowserParent, const InputContext& aInputContext,
+    const InputContextAction& aAction) {
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("SetInputContextForChildProcess(aBrowserParent=0x%p, "
+       "aInputContext=%s , aAction={ mCause=%s, mAction=%s }), "
+       "sFocusedPresContext=0x%p (available: %s), "
+       "sTextInputHandlingWidget=0x%p (available: %s), "
+       "BrowserParent::GetFocused()=0x%p, sInstalledMenuKeyboardListener=%s",
+       aBrowserParent, ToString(aInputContext).c_str(),
+       ToString(aAction.mCause).c_str(), ToString(aAction.mFocusChange).c_str(),
+       sFocusedPresContext.get(),
+       GetBoolName(CanHandleWith(sFocusedPresContext)),
+       sTextInputHandlingWidget,
+       GetBoolName(sTextInputHandlingWidget &&
+                   !sTextInputHandlingWidget->Destroyed()),
+       BrowserParent::GetFocused(),
+       GetBoolName(sInstalledMenuKeyboardListener)));
+
+  if (aBrowserParent != BrowserParent::GetFocused()) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  SetInputContextForChildProcess(), FAILED, "
+             "because non-focused tab parent tries to set input context"));
+    return;
+  }
+
+  if (NS_WARN_IF(!CanHandleWith(sFocusedPresContext))) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  SetInputContextForChildProcess(), FAILED, "
+             "due to no focused presContext"));
+    return;
+  }
+
+  if (NS_WARN_IF(!sTextInputHandlingWidget) ||
+      NS_WARN_IF(sTextInputHandlingWidget->Destroyed())) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  SetInputContextForChildProcess(), FAILED, "
+             "due to the widget for the nsPresContext has gone"));
+    return;
+  }
+
+  const OwningNonNull<nsIWidget> textInputHandlingWidget =
+      *sTextInputHandlingWidget;
+#ifdef DEBUG
+  {
+    nsCOMPtr<nsIWidget> currentTextInputHandlingWidget =
+        sFocusedPresContext->GetTextInputHandlingWidget();
+    MOZ_ASSERT(!currentTextInputHandlingWidget ||
+               currentTextInputHandlingWidget == textInputHandlingWidget);
+  }
+#endif  // DEBUG
+  MOZ_ASSERT(aInputContext.mOrigin == InputContext::ORIGIN_CONTENT);
+
+  sActiveChildInputContext = aInputContext;
+  MOZ_ASSERT(HasActiveChildSetInputContext());
+
+  // If input context is changed in remote process while menu keyboard listener
+  // is installed, this process shouldn't set input context now.  When it's
+  // uninstalled, input context should be restored from
+  // sActiveChildInputContext.
+  if (sInstalledMenuKeyboardListener) {
+    MOZ_LOG(sISMLog, LogLevel::Info,
+            ("  SetInputContextForChildProcess(), waiting to set input context "
+             "until menu keyboard listener is uninstalled"));
+    return;
+  }
+
+  SetInputContext(textInputHandlingWidget, aInputContext, aAction);
+}
+
+MOZ_CAN_RUN_SCRIPT static bool IsNextFocusableElementTextControl(
+    const Element* aInputContent) {
+  RefPtr<nsFocusManager> fm = nsFocusManager::GetFocusManager();
+  if (MOZ_UNLIKELY(!fm)) {
+    return false;
+  }
+  nsCOMPtr<nsIContent> nextContent;
+  const RefPtr<Element> inputContent = const_cast<Element*>(aInputContent);
+  const nsCOMPtr<nsPIDOMWindowOuter> outerWindow =
+      aInputContent->OwnerDoc()->GetWindow();
+  nsresult rv = fm->DetermineElementToMoveFocus(
+      outerWindow, inputContent, nsIFocusManager::MOVEFOCUS_FORWARD, true,
+      false, getter_AddRefs(nextContent));
+  if (NS_WARN_IF(NS_FAILED(rv)) || !nextContent) {
+    return false;
+  }
+  nextContent = nextContent->FindFirstNonChromeOnlyAccessContent();
+  nsCOMPtr<nsIFormControl> nextControl = do_QueryInterface(nextContent);
+  if (!nextControl || !nextControl->IsTextControl(false)) {
+    return false;
+  }
+
+  // XXX We don't consider next element is date/time control yet.
+  nsGenericHTMLElement* nextElement =
+      nsGenericHTMLElement::FromNodeOrNull(nextContent);
+  if (!nextElement) {
+    return false;
+  }
+  bool focusable = false;
+  nextElement->IsHTMLFocusable(false, &focusable, nullptr);
+  if (!focusable) {
+    return false;
+  }
+
+  // Check readonly attribute.
+  if (nextElement->IsHTMLElement(nsGkAtoms::textarea)) {
+    HTMLTextAreaElement* textAreaElement =
+        HTMLTextAreaElement::FromNodeOrNull(nextElement);
+    return !textAreaElement->ReadOnly();
+  }
+
+  // If neither textarea nor input, what element type?
+  MOZ_DIAGNOSTIC_ASSERT(nextElement->IsHTMLElement(nsGkAtoms::input));
+
+  HTMLInputElement* inputElement =
+      HTMLInputElement::FromNodeOrNull(nextElement);
+  return !inputElement->ReadOnly();
+}
+
+static void GetInputType(const IMEState& aState, const nsIContent& aContent,
+                         nsAString& aInputType) {
+  // NOTE: If you change here, you may need to update
+  //       widget::InputContext::GatNativeKeyBindings too.
+  if (aContent.IsHTMLElement(nsGkAtoms::input)) {
+    const HTMLInputElement* inputElement =
+        HTMLInputElement::FromNode(&aContent);
+    if (inputElement->HasBeenTypePassword() && aState.IsEditable()) {
+      aInputType.AssignLiteral("password");
+    } else {
+      inputElement->GetType(aInputType);
+    }
+  } else if (aContent.IsHTMLElement(nsGkAtoms::textarea)) {
+    aInputType.Assign(nsGkAtoms::textarea->GetUTF16String());
+  }
+}
+
+MOZ_CAN_RUN_SCRIPT static void GetActionHint(const IMEState& aState,
+                                             const nsIContent& aContent,
+                                             nsAString& aActionHint) {
+  MOZ_ASSERT(aContent.IsHTMLElement());
+
+  if (aState.IsEditable() && StaticPrefs::dom_forms_enterkeyhint()) {
+    nsGenericHTMLElement::FromNode(&aContent)->GetEnterKeyHint(aActionHint);
+
+    // If enterkeyhint is set, we don't infer action hint.
+    if (!aActionHint.IsEmpty()) {
+      return;
+    }
+  }
+
+  if (!aContent.IsAnyOfHTMLElements(nsGkAtoms::input, nsGkAtoms::textarea)) {
+    return;
+  }
+
+  // XXX This is old compatibility, but we might be able to remove this.
+  aContent.AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::moz_action_hint,
+                                aActionHint);
+
+  if (!aActionHint.IsEmpty()) {
+    ToLowerCase(aActionHint);
+    return;
+  }
+
+  // Get the input content corresponding to the focused node,
+  // which may be an anonymous child of the input content.
+  MOZ_ASSERT(&aContent == aContent.FindFirstNonChromeOnlyAccessContent());
+  const HTMLInputElement* inputElement = HTMLInputElement::FromNode(aContent);
+  if (!inputElement) {
+    return;
+  }
+
+  // If we don't have an action hint and
+  // return won't submit the form, use "maybenext".
+  bool willSubmit = false;
+  bool isLastElement = false;
+  HTMLFormElement* formElement = inputElement->GetForm();
+  // is this a form and does it have a default submit element?
+  if (formElement) {
+    if (formElement->IsLastActiveElement(inputElement)) {
+      isLastElement = true;
+    }
+
+    if (formElement->GetDefaultSubmitElement()) {
+      willSubmit = true;
+      // is this an html form...
+    } else {
+      // ... and does it only have a single text input element ?
+      if (!formElement->ImplicitSubmissionIsDisabled() ||
+          // ... or is this the last non-disabled element?
+          isLastElement) {
+        willSubmit = true;
+      }
+    }
+  }
+
+  if (!isLastElement && formElement) {
+    // If next tabbable content in form is text control, hint should be "next"
+    // even there is submit in form.
+    // MOZ_KnownLive(inputElement) because it's an alias of aContent.
+    if (IsNextFocusableElementTextControl(MOZ_KnownLive(inputElement))) {
+      // This is focusable text control
+      // XXX What good hint for read only field?
+      aActionHint.AssignLiteral("maybenext");
+      return;
+    }
+  }
+
+  if (!willSubmit) {
+    return;
+  }
+
+  if (inputElement->ControlType() == FormControlType::InputSearch) {
+    aActionHint.AssignLiteral("search");
+    return;
+  }
+
+  aActionHint.AssignLiteral("go");
+}
+
+static void GetInputMode(const IMEState& aState, const nsIContent& aContent,
+                         nsAString& aInputMode) {
+  if (aState.IsEditable() &&
+      (StaticPrefs::dom_forms_inputmode() ||
+       nsContentUtils::IsChromeDoc(aContent.OwnerDoc()))) {
+    aContent.AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::inputmode,
+                                  aInputMode);
+    if (aContent.IsHTMLElement(nsGkAtoms::input) &&
+        aInputMode.EqualsLiteral("mozAwesomebar")) {
+      if (!nsContentUtils::IsChromeDoc(aContent.OwnerDoc())) {
+        // mozAwesomebar should be allowed only in chrome
+        aInputMode.Truncate();
+      }
+    } else {
+      ToLowerCase(aInputMode);
+    }
+  }
+}
+
+static void GetAutocapitalize(const IMEState& aState, const Element& aElement,
+                              const InputContext& aInputContext,
+                              nsAString& aAutocapitalize) {
+  if (aElement.IsHTMLElement() && aState.IsEditable() &&
+      StaticPrefs::dom_forms_autocapitalize() &&
+      aInputContext.IsAutocapitalizeSupported()) {
+    nsGenericHTMLElement::FromNode(&aElement)->GetAutocapitalize(
+        aAutocapitalize);
+  }
+}
+
+// static
+void IMEStateManager::SetIMEState(const IMEState& aState,
+                                  const nsPresContext* aPresContext,
+                                  Element* aElement, nsIWidget& aWidget,
+                                  InputContextAction aAction,
+                                  InputContext::Origin aOrigin) {
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("SetIMEState(aState=%s, nsPresContext=0x%p, aElement=0x%p "
+           "(BrowserParent=0x%p), aWidget=0x%p, aAction={ mCause=%s, "
+           "mFocusChange=%s }, aOrigin=%s)",
+           ToString(aState).c_str(), aPresContext, aElement,
+           BrowserParent::GetFrom(aElement), &aWidget,
+           ToString(aAction.mCause).c_str(),
+           ToString(aAction.mFocusChange).c_str(), ToChar(aOrigin)));
+
+  InputContext context;
+  context.mIMEState = aState;
+  if (aPresContext) {
+    if (nsIURI* uri = aPresContext->Document()->GetDocumentURI()) {
+      // We don't need to and should not expose special URLs such as:
+      // about: Any apps like IME should work normally and constantly in any
+      //        default pages such as about:blank, about:home, etc in either
+      //        the main process or a content process.
+      // blob: This may contain big data.  If we copy it to the main process,
+      //       it may make the heap dirty which makes the process slower.
+      // chrome: Same as about, any apps should work normally and constantly in
+      //         any chrome documents.
+      // data: Any native apps in the environment shouldn't change the behavior
+      //       with the data URL's content and it may contain too big data.
+      // file: The file path may contain private things and we shouldn't let
+      //       other apps like IME know which one is touched by the user because
+      //       malicious text services may like files which are explicitly used
+      //       by the user better.
+      if (uri->SchemeIs("http") || uri->SchemeIs("https")) {
+        // Note that we don't need to expose UserPass, Query and Reference to
+        // IME since they may contain sensitive data, but non-malicious text
+        // services must not require these data.
+        nsCOMPtr<nsIURI> exposableURL;
+        if (NS_SUCCEEDED(NS_MutateURI(uri)
+                             .SetQuery(""_ns)
+                             .SetRef(""_ns)
+                             .SetUserPass(""_ns)
+                             .Finalize(exposableURL))) {
+          context.mURI = std::move(exposableURL);
+        }
+      }
+    }
+  }
+  context.mOrigin = aOrigin;
+
+  context.mHasHandledUserInput =
+      aPresContext && aPresContext->PresShell()->HasHandledUserInput();
+
+  context.mInPrivateBrowsing =
+      aPresContext &&
+      nsContentUtils::IsInPrivateBrowsing(aPresContext->Document());
+
+  const RefPtr<Element> focusedElement =
+      aElement ? Element::FromNodeOrNull(
+                     aElement->FindFirstNonChromeOnlyAccessContent())
+               : nullptr;
+
+  if (focusedElement && focusedElement->IsHTMLElement()) {
+    GetInputType(aState, *focusedElement, context.mHTMLInputType);
+    GetActionHint(aState, *focusedElement, context.mActionHint);
+    GetInputMode(aState, *focusedElement, context.mHTMLInputMode);
+    GetAutocapitalize(aState, *focusedElement, context,
+                      context.mAutocapitalize);
+  }
+
+  if (aAction.mCause == InputContextAction::CAUSE_UNKNOWN &&
+      nsContentUtils::LegacyIsCallerChromeOrNativeCode()) {
+    aAction.mCause = InputContextAction::CAUSE_UNKNOWN_CHROME;
+  }
+
+  if ((aAction.mCause == InputContextAction::CAUSE_UNKNOWN ||
+       aAction.mCause == InputContextAction::CAUSE_UNKNOWN_CHROME) &&
+      UserActivation::IsHandlingUserInput()) {
+    aAction.mCause =
+        UserActivation::IsHandlingKeyboardInput()
+            ? InputContextAction::CAUSE_UNKNOWN_DURING_KEYBOARD_INPUT
+            : InputContextAction::CAUSE_UNKNOWN_DURING_NON_KEYBOARD_INPUT;
+  }
+
+  SetInputContext(aWidget, context, aAction);
+}
+
+// static
+void IMEStateManager::SetInputContext(nsIWidget& aWidget,
+                                      const InputContext& aInputContext,
+                                      const InputContextAction& aAction) {
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("SetInputContext(aWidget=0x%p, aInputContext=%s, "
+       "aAction={ mCause=%s, mAction=%s }), BrowserParent::GetFocused()=0x%p",
+       &aWidget, ToString(aInputContext).c_str(),
+       ToString(aAction.mCause).c_str(), ToString(aAction.mFocusChange).c_str(),
+       BrowserParent::GetFocused()));
+
+  OwningNonNull<nsIWidget> widget = aWidget;
+  widget->SetInputContext(aInputContext, aAction);
+  sActiveInputContextWidget = widget;
+}
+
+// static
+void IMEStateManager::EnsureTextCompositionArray() {
+  if (sTextCompositions) {
+    return;
+  }
+  sTextCompositions = new TextCompositionArray();
+}
+
+// static
+void IMEStateManager::DispatchCompositionEvent(
+    nsINode* aEventTargetNode, nsPresContext* aPresContext,
+    BrowserParent* aBrowserParent, WidgetCompositionEvent* aCompositionEvent,
+    nsEventStatus* aStatus, EventDispatchingCallback* aCallBack,
+    bool aIsSynthesized) {
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("DispatchCompositionEvent(aNode=0x%p, "
+       "aPresContext=0x%p, aCompositionEvent={ mMessage=%s, "
+       "mNativeIMEContext={ mRawNativeIMEContext=0x%" PRIXPTR ", "
+       "mOriginProcessID=0x%" PRIX64 " }, mWidget(0x%p)={ "
+       "GetNativeIMEContext()={ mRawNativeIMEContext=0x%" PRIXPTR ", "
+       "mOriginProcessID=0x%" PRIX64 " }, Destroyed()=%s }, "
+       "mFlags={ mIsTrusted=%s, mPropagationStopped=%s } }, "
+       "aIsSynthesized=%s), browserParent=%p",
+       aEventTargetNode, aPresContext, ToChar(aCompositionEvent->mMessage),
+       aCompositionEvent->mNativeIMEContext.mRawNativeIMEContext,
+       aCompositionEvent->mNativeIMEContext.mOriginProcessID,
+       aCompositionEvent->mWidget.get(),
+       aCompositionEvent->mWidget->GetNativeIMEContext().mRawNativeIMEContext,
+       aCompositionEvent->mWidget->GetNativeIMEContext().mOriginProcessID,
+       GetBoolName(aCompositionEvent->mWidget->Destroyed()),
+       GetBoolName(aCompositionEvent->mFlags.mIsTrusted),
+       GetBoolName(aCompositionEvent->mFlags.mPropagationStopped),
+       GetBoolName(aIsSynthesized), aBrowserParent));
+
+  if (NS_WARN_IF(!aCompositionEvent->IsTrusted()) ||
+      NS_WARN_IF(aCompositionEvent->PropagationStopped())) {
+    return;
+  }
+
+  MOZ_ASSERT(aCompositionEvent->mMessage != eCompositionUpdate,
+             "compositionupdate event shouldn't be dispatched manually");
+
+  EnsureTextCompositionArray();
+
+  RefPtr<TextComposition> composition =
+      sTextCompositions->GetCompositionFor(aCompositionEvent);
+  if (!composition) {
+    // If synthesized event comes after delayed native composition events
+    // for request of commit or cancel, we should ignore it.
+    if (NS_WARN_IF(aIsSynthesized)) {
+      return;
+    }
+    MOZ_LOG(sISMLog, LogLevel::Debug,
+            ("  DispatchCompositionEvent(), "
+             "adding new TextComposition to the array"));
+    MOZ_ASSERT(aCompositionEvent->mMessage == eCompositionStart);
+    composition = new TextComposition(aPresContext, aEventTargetNode,
+                                      aBrowserParent, aCompositionEvent);
+    sTextCompositions->AppendElement(composition);
+  }
+#ifdef DEBUG
+  else {
+    MOZ_ASSERT(aCompositionEvent->mMessage != eCompositionStart);
+  }
+#endif  // #ifdef DEBUG
+
+  // Dispatch the event on composing target.
+  composition->DispatchCompositionEvent(aCompositionEvent, aStatus, aCallBack,
+                                        aIsSynthesized);
+
+  // WARNING: the |composition| might have been destroyed already.
+
+  // Remove the ended composition from the array.
+  // NOTE: When TextComposition is synthesizing compositionend event for
+  //       emulating a commit, the instance shouldn't be removed from the array
+  //       because IME may perform it later.  Then, we need to ignore the
+  //       following commit events in TextComposition::DispatchEvent().
+  //       However, if commit or cancel for a request is performed synchronously
+  //       during not safe to dispatch events, PresShell must have discarded
+  //       compositionend event.  Then, the synthesized compositionend event is
+  //       the last event for the composition.  In this case, we need to
+  //       destroy the TextComposition with synthesized compositionend event.
+  if ((!aIsSynthesized ||
+       composition->WasNativeCompositionEndEventDiscarded()) &&
+      aCompositionEvent->CausesDOMCompositionEndEvent()) {
+    TextCompositionArray::index_type i =
+        sTextCompositions->IndexOf(aCompositionEvent->mWidget);
+    if (i != TextCompositionArray::NoIndex) {
+      MOZ_LOG(
+          sISMLog, LogLevel::Debug,
+          ("  DispatchCompositionEvent(), "
+           "removing TextComposition from the array since NS_COMPOSTION_END "
+           "was dispatched"));
+      sTextCompositions->ElementAt(i)->Destroy();
+      sTextCompositions->RemoveElementAt(i);
+    }
+  }
+}
+
+// static
+IMEContentObserver* IMEStateManager::GetActiveContentObserver() {
+  return sActiveIMEContentObserver;
+}
+
+// static
+nsIContent* IMEStateManager::GetRootContent(nsPresContext* aPresContext) {
+  Document* doc = aPresContext->Document();
+  if (NS_WARN_IF(!doc)) {
+    return nullptr;
+  }
+  return doc->GetRootElement();
+}
+
+// static
+void IMEStateManager::HandleSelectionEvent(
+    nsPresContext* aPresContext, nsIContent* aEventTargetContent,
+    WidgetSelectionEvent* aSelectionEvent) {
+  RefPtr<BrowserParent> browserParent = GetActiveBrowserParent();
+  if (!browserParent) {
+    browserParent = BrowserParent::GetFrom(aEventTargetContent
+                                               ? aEventTargetContent
+                                               : GetRootContent(aPresContext));
+  }
+
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("HandleSelectionEvent(aPresContext=0x%p, "
+       "aEventTargetContent=0x%p, aSelectionEvent={ mMessage=%s, "
+       "mFlags={ mIsTrusted=%s } }), browserParent=%p",
+       aPresContext, aEventTargetContent, ToChar(aSelectionEvent->mMessage),
+       GetBoolName(aSelectionEvent->mFlags.mIsTrusted), browserParent.get()));
+
+  if (!aSelectionEvent->IsTrusted()) {
+    return;
+  }
+
+  RefPtr<TextComposition> composition =
+      sTextCompositions
+          ? sTextCompositions->GetCompositionFor(aSelectionEvent->mWidget)
+          : nullptr;
+  if (composition) {
+    // When there is a composition, TextComposition should guarantee that the
+    // selection event will be handled in same target as composition events.
+    composition->HandleSelectionEvent(aSelectionEvent);
+  } else {
+    // When there is no composition, the selection event should be handled
+    // in the aPresContext or browserParent.
+    TextComposition::HandleSelectionEvent(aPresContext, browserParent,
+                                          aSelectionEvent);
+  }
+}
+
+// static
+void IMEStateManager::OnCompositionEventDiscarded(
+    WidgetCompositionEvent* aCompositionEvent) {
+  // Note that this method is never called for synthesized events for emulating
+  // commit or cancel composition.
+
+  MOZ_LOG(
+      sISMLog, LogLevel::Info,
+      ("OnCompositionEventDiscarded(aCompositionEvent={ "
+       "mMessage=%s, mNativeIMEContext={ mRawNativeIMEContext=0x%" PRIXPTR ", "
+       "mOriginProcessID=0x%" PRIX64 " }, mWidget(0x%p)={ "
+       "GetNativeIMEContext()={ mRawNativeIMEContext=0x%" PRIXPTR ", "
+       "mOriginProcessID=0x%" PRIX64 " }, Destroyed()=%s }, "
+       "mFlags={ mIsTrusted=%s } })",
+       ToChar(aCompositionEvent->mMessage),
+       aCompositionEvent->mNativeIMEContext.mRawNativeIMEContext,
+       aCompositionEvent->mNativeIMEContext.mOriginProcessID,
+       aCompositionEvent->mWidget.get(),
+       aCompositionEvent->mWidget->GetNativeIMEContext().mRawNativeIMEContext,
+       aCompositionEvent->mWidget->GetNativeIMEContext().mOriginProcessID,
+       GetBoolName(aCompositionEvent->mWidget->Destroyed()),
+       GetBoolName(aCompositionEvent->mFlags.mIsTrusted)));
+
+  if (!aCompositionEvent->IsTrusted()) {
+    return;
+  }
+
+  // Ignore compositionstart for now because sTextCompositions may not have
+  // been created yet.
+  if (aCompositionEvent->mMessage == eCompositionStart) {
+    return;
+  }
+
+  RefPtr<TextComposition> composition =
+      sTextCompositions->GetCompositionFor(aCompositionEvent->mWidget);
+  if (!composition) {
+    // If the PresShell has been being destroyed during composition,
+    // a TextComposition instance for the composition was already removed from
+    // the array and destroyed in OnDestroyPresContext().  Therefore, we may
+    // fail to retrieve a TextComposition instance here.
+    MOZ_LOG(sISMLog, LogLevel::Info,
+            ("  OnCompositionEventDiscarded(), "
+             "TextComposition instance for the widget has already gone"));
+    return;
+  }
+  composition->OnCompositionEventDiscarded(aCompositionEvent);
+}
+
+// static
+nsresult IMEStateManager::NotifyIME(IMEMessage aMessage, nsIWidget* aWidget,
+                                    BrowserParent* aBrowserParent) {
+  return IMEStateManager::NotifyIME(IMENotification(aMessage), aWidget,
+                                    aBrowserParent);
+}
+
+// static
+nsresult IMEStateManager::NotifyIME(const IMENotification& aNotification,
+                                    nsIWidget* aWidget,
+                                    BrowserParent* aBrowserParent) {
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("NotifyIME(aNotification={ mMessage=%s }, "
+           "aWidget=0x%p, aBrowserParent=0x%p), sFocusedIMEWidget=0x%p, "
+           "BrowserParent::GetFocused()=0x%p, sFocusedIMEBrowserParent=0x%p, "
+           "aBrowserParent == BrowserParent::GetFocused()=%s, "
+           "aBrowserParent == sFocusedIMEBrowserParent=%s, "
+           "CanSendNotificationToWidget()=%s",
+           ToChar(aNotification.mMessage), aWidget, aBrowserParent,
+           sFocusedIMEWidget, BrowserParent::GetFocused(),
+           sFocusedIMEBrowserParent.get(),
+           GetBoolName(aBrowserParent == BrowserParent::GetFocused()),
+           GetBoolName(aBrowserParent == sFocusedIMEBrowserParent),
+           GetBoolName(CanSendNotificationToWidget())));
+
+  if (NS_WARN_IF(!aWidget)) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  NotifyIME(), FAILED due to no widget"));
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  switch (aNotification.mMessage) {
+    case NOTIFY_IME_OF_FOCUS: {
+      MOZ_ASSERT(CanSendNotificationToWidget());
+
+      // If focus notification comes from a remote browser which already lost
+      // focus, we shouldn't accept the focus notification.  Then, following
+      // notifications from the process will be ignored.
+      if (aBrowserParent != BrowserParent::GetFocused()) {
+        MOZ_LOG(sISMLog, LogLevel::Warning,
+                ("  NotifyIME(), WARNING, the received focus notification is "
+                 "ignored, because its associated BrowserParent did not match"
+                 "the focused BrowserParent."));
+        return NS_OK;
+      }
+      // If IME focus is already set, first blur the currently-focused
+      // IME widget
+      if (sFocusedIMEWidget) {
+        // XXX Why don't we first request the previously-focused IME
+        // widget to commit the composition?
+        MOZ_ASSERT(
+            sFocusedIMEBrowserParent || aBrowserParent,
+            "This case shouldn't be caused by focus move in this process");
+        MOZ_LOG(sISMLog, LogLevel::Warning,
+                ("  NotifyIME(), WARNING, received focus notification with ")
+                 "non-null sFocusedIMEWidget. How come "
+                 "OnFocusMovedBetweenBrowsers did not blur it already?");
+        nsCOMPtr<nsIWidget> focusedIMEWidget(sFocusedIMEWidget);
+        sFocusedIMEWidget = nullptr;
+        sFocusedIMEBrowserParent = nullptr;
+        focusedIMEWidget->NotifyIME(IMENotification(NOTIFY_IME_OF_BLUR));
+      }
+#ifdef DEBUG
+      if (aBrowserParent) {
+        nsCOMPtr<nsIWidget> browserParentWidget =
+            aBrowserParent->GetTextInputHandlingWidget();
+        MOZ_ASSERT(browserParentWidget == aWidget);
+      }
+#endif
+      sFocusedIMEBrowserParent = aBrowserParent;
+      sFocusedIMEWidget = aWidget;
+      nsCOMPtr<nsIWidget> widget(aWidget);
+      MOZ_LOG(
+          sISMLog, LogLevel::Info,
+          ("  NotifyIME(), about to call widget->NotifyIME() for IME focus"));
+      return widget->NotifyIME(aNotification);
+    }
+    case NOTIFY_IME_OF_BLUR: {
+      if (aBrowserParent != sFocusedIMEBrowserParent) {
+        MOZ_LOG(sISMLog, LogLevel::Warning,
+                ("  NotifyIME(), WARNING, the received blur notification is "
+                 "ignored "
+                 "because it's not from current focused IME browser"));
+        return NS_OK;
+      }
+      if (!sFocusedIMEWidget) {
+        MOZ_LOG(
+            sISMLog, LogLevel::Error,
+            ("  NotifyIME(), WARNING, received blur notification but there is "
+             "no focused IME widget"));
+        return NS_OK;
+      }
+      if (NS_WARN_IF(sFocusedIMEWidget != aWidget)) {
+        MOZ_LOG(sISMLog, LogLevel::Warning,
+                ("  NotifyIME(), WARNING, the received blur notification is "
+                 "ignored "
+                 "because it's not for current focused IME widget"));
+        return NS_OK;
+      }
+      nsCOMPtr<nsIWidget> focusedIMEWidget(sFocusedIMEWidget);
+      sFocusedIMEWidget = nullptr;
+      sFocusedIMEBrowserParent = nullptr;
+      return CanSendNotificationToWidget()
+                 ? focusedIMEWidget->NotifyIME(
+                       IMENotification(NOTIFY_IME_OF_BLUR))
+                 : NS_OK;
+    }
+    case NOTIFY_IME_OF_SELECTION_CHANGE:
+    case NOTIFY_IME_OF_TEXT_CHANGE:
+    case NOTIFY_IME_OF_POSITION_CHANGE:
+    case NOTIFY_IME_OF_MOUSE_BUTTON_EVENT:
+    case NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED: {
+      if (aBrowserParent != sFocusedIMEBrowserParent) {
+        MOZ_LOG(
+            sISMLog, LogLevel::Warning,
+            ("  NotifyIME(), WARNING, the received content change notification "
+             "is ignored because it's not from current focused IME browser"));
+        return NS_OK;
+      }
+      if (!sFocusedIMEWidget) {
+        MOZ_LOG(
+            sISMLog, LogLevel::Warning,
+            ("  NotifyIME(), WARNING, the received content change notification "
+             "is ignored because there is no focused IME widget"));
+        return NS_OK;
+      }
+      if (NS_WARN_IF(sFocusedIMEWidget != aWidget)) {
+        MOZ_LOG(
+            sISMLog, LogLevel::Warning,
+            ("  NotifyIME(), WARNING, the received content change notification "
+             "is ignored because it's not for current focused IME widget"));
+        return NS_OK;
+      }
+      if (!CanSendNotificationToWidget()) {
+        return NS_OK;
+      }
+      nsCOMPtr<nsIWidget> widget(aWidget);
+      return widget->NotifyIME(aNotification);
+    }
+    default:
+      // Other notifications should be sent only when there is composition.
+      // So, we need to handle the others below.
+      break;
+  }
+
+  if (!sTextCompositions) {
+    MOZ_LOG(sISMLog, LogLevel::Info,
+            ("  NotifyIME(), the request to IME is ignored because "
+             "there have been no compositions yet"));
+    return NS_OK;
+  }
+
+  RefPtr<TextComposition> composition =
+      sTextCompositions->GetCompositionFor(aWidget);
+  if (!composition) {
+    MOZ_LOG(sISMLog, LogLevel::Info,
+            ("  NotifyIME(), the request to IME is ignored because "
+             "there is no active composition"));
+    return NS_OK;
+  }
+
+  if (aBrowserParent != composition->GetBrowserParent()) {
+    MOZ_LOG(
+        sISMLog, LogLevel::Warning,
+        ("  NotifyIME(), WARNING, the request to IME is ignored because "
+         "it does not come from the remote browser which has the composition "
+         "on aWidget"));
+    return NS_OK;
+  }
+
+  switch (aNotification.mMessage) {
+    case REQUEST_TO_COMMIT_COMPOSITION:
+      return composition->RequestToCommit(aWidget, false);
+    case REQUEST_TO_CANCEL_COMPOSITION:
+      return composition->RequestToCommit(aWidget, true);
+    default:
+      MOZ_CRASH("Unsupported notification");
+  }
+  MOZ_CRASH(
+      "Failed to handle the notification for non-synthesized composition");
+  return NS_ERROR_FAILURE;
+}
+
+// static
+nsresult IMEStateManager::NotifyIME(IMEMessage aMessage,
+                                    nsPresContext* aPresContext,
+                                    BrowserParent* aBrowserParent) {
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("NotifyIME(aMessage=%s, aPresContext=0x%p, aBrowserParent=0x%p)",
+           ToChar(aMessage), aPresContext, aBrowserParent));
+
+  if (NS_WARN_IF(!CanHandleWith(aPresContext))) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsCOMPtr<nsIWidget> widget = aPresContext->GetTextInputHandlingWidget();
+  if (NS_WARN_IF(!widget)) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  NotifyIME(), FAILED due to no widget for the "
+             "nsPresContext"));
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  return NotifyIME(aMessage, widget, aBrowserParent);
+}
+
+// static
+bool IMEStateManager::IsEditable(nsINode* node) {
+  if (node->IsEditable()) {
+    return true;
+  }
+  // |node| might be readwrite (for example, a text control)
+  if (node->IsElement() &&
+      node->AsElement()->State().HasState(ElementState::READWRITE)) {
+    return true;
+  }
+  return false;
+}
+
+// static
+nsINode* IMEStateManager::GetRootEditableNode(const nsPresContext& aPresContext,
+                                              const Element* aElement) {
+  if (aElement) {
+    // If the focused content is in design mode, return is composed document
+    // because aElement may be in UA widget shadow tree.
+    if (aElement->IsInDesignMode()) {
+      return aElement->GetComposedDoc();
+    }
+
+    nsINode* candidateRootNode = const_cast<Element*>(aElement);
+    for (nsINode* node = candidateRootNode; node && IsEditable(node);
+         node = node->GetParentNode()) {
+      // If the node has independent selection like <input type="text"> or
+      // <textarea>, the node should be the root editable node for aElement.
+      // FYI: <select> element also has independent selection but IsEditable()
+      //      returns false.
+      // XXX: If somebody adds new editable element which has independent
+      //      selection but doesn't own editor, we'll need more checks here.
+      // XXX: If aElement is not in native anonymous subtree, checking
+      //      independent selection must be wrong, see bug 1731005.
+      if (node->IsContent() && node->AsContent()->HasIndependentSelection()) {
+        return node;
+      }
+      candidateRootNode = node;
+    }
+    return candidateRootNode;
+  }
+
+  return aPresContext.Document() && aPresContext.Document()->IsInDesignMode()
+             ? aPresContext.Document()
+             : nullptr;
+}
+
+// static
+bool IMEStateManager::IsIMEObserverNeeded(const IMEState& aState) {
+  return aState.IsEditable();
+}
+
+// static
+void IMEStateManager::DestroyIMEContentObserver() {
+  if (!sActiveIMEContentObserver) {
+    MOZ_LOG(sISMLog, LogLevel::Verbose,
+            ("DestroyIMEContentObserver() does nothing"));
+    return;
+  }
+
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("DestroyIMEContentObserver(), destroying "
+           "the active IMEContentObserver..."));
+  RefPtr<IMEContentObserver> tsm = sActiveIMEContentObserver.get();
+  sActiveIMEContentObserver = nullptr;
+  tsm->Destroy();
+}
+
+// static
+void IMEStateManager::CreateIMEContentObserver(EditorBase& aEditorBase,
+                                               Element* aFocusedElement) {
+  MOZ_ASSERT(!sActiveIMEContentObserver);
+  MOZ_ASSERT(sTextInputHandlingWidget);
+  MOZ_ASSERT(sFocusedPresContext);
+  MOZ_ASSERT(IsIMEObserverNeeded(
+      sTextInputHandlingWidget->GetInputContext().mIMEState));
+
+  MOZ_LOG(sISMLog, LogLevel::Info,
+          ("CreateIMEContentObserver(aEditorBase=0x%p, aFocusedElement=0x%p), "
+           "sFocusedPresContext=0x%p, sFocusedElement=0x%p, "
+           "sTextInputHandlingWidget=0x%p (available: %s), "
+           "sActiveIMEContentObserver=0x%p, "
+           "sActiveIMEContentObserver->IsManaging(sFocusedPresContext, "
+           "sFocusedElement)=%s",
+           &aEditorBase, aFocusedElement, sFocusedPresContext.get(),
+           sFocusedElement.get(), sTextInputHandlingWidget,
+           GetBoolName(sTextInputHandlingWidget &&
+                       !sTextInputHandlingWidget->Destroyed()),
+           sActiveIMEContentObserver.get(),
+           GetBoolName(sActiveIMEContentObserver && sFocusedPresContext &&
+                       sActiveIMEContentObserver->IsManaging(
+                           *sFocusedPresContext, sFocusedElement))));
+
+  if (NS_WARN_IF(sTextInputHandlingWidget->Destroyed())) {
+    MOZ_LOG(sISMLog, LogLevel::Error,
+            ("  CreateIMEContentObserver(), FAILED due to "
+             "the widget for the nsPresContext has gone"));
+    return;
+  }
+
+  const OwningNonNull<nsIWidget> textInputHandlingWidget =
+      *sTextInputHandlingWidget;
+
+#ifdef DEBUG
+  {
+    nsCOMPtr<nsIWidget> currentTextInputHandlingWidget =
+        sFocusedPresContext->GetTextInputHandlingWidget();
+    MOZ_ASSERT(currentTextInputHandlingWidget == textInputHandlingWidget);
+  }
+#endif  // DEBUG
+
+  MOZ_LOG(sISMLog, LogLevel::Debug,
+          ("  CreateIMEContentObserver() is creating an "
+           "IMEContentObserver instance..."));
+  sActiveIMEContentObserver = new IMEContentObserver();
+
+  // IMEContentObserver::Init() might create another IMEContentObserver
+  // instance.  So, sActiveIMEContentObserver would be replaced with new one.
+  // We should hold the current instance here.
+  OwningNonNull<IMEContentObserver> activeIMEContentObserver =
+      *sActiveIMEContentObserver;
+  OwningNonNull<nsPresContext> focusedPresContext = *sFocusedPresContext;
+  RefPtr<Element> focusedElement = aFocusedElement;
+  activeIMEContentObserver->Init(textInputHandlingWidget, focusedPresContext,
+                                 focusedElement, aEditorBase);
+}
+
+// static
+nsresult IMEStateManager::GetFocusSelectionAndRootElement(
+    Selection** aSelection, Element** aRootElement) {
+  if (!sActiveIMEContentObserver) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  return sActiveIMEContentObserver->GetSelectionAndRoot(aSelection,
+                                                        aRootElement);
+}
+
+// static
+already_AddRefed<TextComposition> IMEStateManager::GetTextCompositionFor(
+    nsIWidget* aWidget) {
+  if (!sTextCompositions) {
+    return nullptr;
+  }
+  RefPtr<TextComposition> textComposition =
+      sTextCompositions->GetCompositionFor(aWidget);
+  return textComposition.forget();
+}
+
+// static
+already_AddRefed<TextComposition> IMEStateManager::GetTextCompositionFor(
+    const WidgetCompositionEvent* aCompositionEvent) {
+  if (!sTextCompositions) {
+    return nullptr;
+  }
+  RefPtr<TextComposition> textComposition =
+      sTextCompositions->GetCompositionFor(aCompositionEvent);
+  return textComposition.forget();
+}
+
+// static
+already_AddRefed<TextComposition> IMEStateManager::GetTextCompositionFor(
+    nsPresContext* aPresContext) {
+  if (!sTextCompositions) {
+    return nullptr;
+  }
+  RefPtr<TextComposition> textComposition =
+      sTextCompositions->GetCompositionFor(aPresContext);
+  return textComposition.forget();
+}
+
+}  // namespace mozilla