Add m-esr52 at 52.6.0

1 files changed, 1869 insertions, 0 deletions

diff --git a/dom/events/IMEContentObserver.cpp b/dom/events/IMEContentObserver.cpp
new file mode 100644
index 000000000..a690cfa64
--- /dev/null
+++ b/dom/events/IMEContentObserver.cpp
@@ -0,0 +1,1869 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Logging.h"
+
+#include "ContentEventHandler.h"
+#include "IMEContentObserver.h"
+#include "mozilla/AsyncEventDispatcher.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/EventStateManager.h"
+#include "mozilla/IMEStateManager.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/TextComposition.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/dom/Element.h"
+#include "nsContentUtils.h"
+#include "nsGkAtoms.h"
+#include "nsIAtom.h"
+#include "nsIContent.h"
+#include "nsIDocument.h"
+#include "nsIDOMDocument.h"
+#include "nsIDOMRange.h"
+#include "nsIEditorIMESupport.h"
+#include "nsIFrame.h"
+#include "nsINode.h"
+#include "nsIPresShell.h"
+#include "nsISelectionController.h"
+#include "nsISelectionPrivate.h"
+#include "nsISupports.h"
+#include "nsIWidget.h"
+#include "nsPresContext.h"
+#include "nsWeakReference.h"
+#include "WritingModes.h"
+
+namespace mozilla {
+
+using namespace widget;
+
+LazyLogModule sIMECOLog("IMEContentObserver");
+
+static const char*
+ToChar(bool aBool)
+{
+  return aBool ? "true" : "false";
+}
+
+class WritingModeToString final : public nsAutoCString
+{
+public:
+  explicit WritingModeToString(const WritingMode& aWritingMode)
+  {
+    if (!aWritingMode.IsVertical()) {
+      AssignLiteral("Horizontal");
+      return;
+    }
+    if (aWritingMode.IsVerticalLR()) {
+      AssignLiteral("Vertical (LR)");
+      return;
+    }
+    AssignLiteral("Vertical (RL)");
+  }
+  virtual ~WritingModeToString() {}
+};
+
+class SelectionChangeDataToString final : public nsAutoCString
+{
+public:
+  explicit SelectionChangeDataToString(
+             const IMENotification::SelectionChangeDataBase& aData)
+  {
+    if (!aData.IsValid()) {
+      AppendLiteral("{ IsValid()=false }");
+      return;
+    }
+    AppendPrintf("{ mOffset=%u, ", aData.mOffset);
+    if (aData.mString->Length() > 20) {
+      AppendPrintf("mString.Length()=%u, ", aData.mString->Length());
+    } else {
+      AppendPrintf("mString=\"%s\" (Length()=%u), ",
+                   NS_ConvertUTF16toUTF8(*aData.mString).get(),
+                   aData.mString->Length());
+    }
+    AppendPrintf("GetWritingMode()=%s, mReversed=%s, mCausedByComposition=%s, "
+                 "mCausedBySelectionEvent=%s }",
+                 WritingModeToString(aData.GetWritingMode()).get(),
+                 ToChar(aData.mReversed),
+                 ToChar(aData.mCausedByComposition),
+                 ToChar(aData.mCausedBySelectionEvent));
+  }
+  virtual ~SelectionChangeDataToString() {}
+};
+
+class TextChangeDataToString final : public nsAutoCString
+{
+public:
+  explicit TextChangeDataToString(
+             const IMENotification::TextChangeDataBase& aData)
+  {
+    if (!aData.IsValid()) {
+      AppendLiteral("{ IsValid()=false }");
+      return;
+    }
+    AppendPrintf("{ mStartOffset=%u, mRemovedEndOffset=%u, mAddedEndOffset=%u, "
+                 "mCausedOnlyByComposition=%s, "
+                 "mIncludingChangesDuringComposition=%s, "
+                 "mIncludingChangesWithoutComposition=%s }",
+                 aData.mStartOffset, aData.mRemovedEndOffset,
+                 aData.mAddedEndOffset,
+                 ToChar(aData.mCausedOnlyByComposition),
+                 ToChar(aData.mIncludingChangesDuringComposition),
+                 ToChar(aData.mIncludingChangesWithoutComposition));
+  }
+  virtual ~TextChangeDataToString() {}
+};
+
+/******************************************************************************
+ * mozilla::IMEContentObserver
+ ******************************************************************************/
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(IMEContentObserver)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(IMEContentObserver)
+  nsAutoScriptBlocker scriptBlocker;
+
+  tmp->NotifyIMEOfBlur();
+  tmp->UnregisterObservers();
+
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mSelection)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mRootContent)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mEditableNode)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mDocShell)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mEditor)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mEndOfAddedTextCache.mContainerNode)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mStartOfRemovingTextRangeCache.mContainerNode)
+
+  tmp->mUpdatePreference.mWantUpdates = nsIMEUpdatePreference::NOTIFY_NOTHING;
+  tmp->mESM = nullptr;
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(IMEContentObserver)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mWidget)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mFocusedWidget)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSelection)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mRootContent)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mEditableNode)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDocShell)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mEditor)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mEndOfAddedTextCache.mContainerNode)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(
+    mStartOfRemovingTextRangeCache.mContainerNode)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(IMEContentObserver)
+ NS_INTERFACE_MAP_ENTRY(nsISelectionListener)
+ NS_INTERFACE_MAP_ENTRY(nsIMutationObserver)
+ NS_INTERFACE_MAP_ENTRY(nsIReflowObserver)
+ NS_INTERFACE_MAP_ENTRY(nsIScrollObserver)
+ NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
+ NS_INTERFACE_MAP_ENTRY(nsIEditorObserver)
+ NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsISelectionListener)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(IMEContentObserver)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(IMEContentObserver)
+
+IMEContentObserver::IMEContentObserver()
+  : mESM(nullptr)
+  , mSuppressNotifications(0)
+  , mPreCharacterDataChangeLength(-1)
+  , mSendingNotification(NOTIFY_IME_OF_NOTHING)
+  , mIsObserving(false)
+  , mIMEHasFocus(false)
+  , mNeedsToNotifyIMEOfFocusSet(false)
+  , mNeedsToNotifyIMEOfTextChange(false)
+  , mNeedsToNotifyIMEOfSelectionChange(false)
+  , mNeedsToNotifyIMEOfPositionChange(false)
+  , mNeedsToNotifyIMEOfCompositionEventHandled(false)
+  , mIsHandlingQueryContentEvent(false)
+{
+#ifdef DEBUG
+  mTextChangeData.Test();
+#endif
+}
+
+void
+IMEContentObserver::Init(nsIWidget* aWidget,
+                         nsPresContext* aPresContext,
+                         nsIContent* aContent,
+                         nsIEditor* aEditor)
+{
+  State state = GetState();
+  if (NS_WARN_IF(state == eState_Observing)) {
+    return; // Nothing to do.
+  }
+
+  bool firstInitialization = state != eState_StoppedObserving;
+  if (!firstInitialization) {
+    // If this is now trying to initialize with new contents, all observers
+    // should be registered again for simpler implementation.
+    UnregisterObservers();
+    // Clear members which may not be initialized again.
+    Clear();
+  }
+
+  mESM = aPresContext->EventStateManager();
+  mESM->OnStartToObserveContent(this);
+
+  mWidget = aWidget;
+
+  if (aWidget->GetInputContext().mIMEState.mEnabled == IMEState::PLUGIN) {
+    if (!InitWithPlugin(aPresContext, aContent)) {
+      Clear();
+      return;
+    }
+  } else {
+    if (!InitWithEditor(aPresContext, aContent, aEditor)) {
+      Clear();
+      return;
+    }
+  }
+
+  if (firstInitialization) {
+    // Now, try to send NOTIFY_IME_OF_FOCUS to IME via the widget.
+    MaybeNotifyIMEOfFocusSet();
+    // When this is called first time, IME has not received NOTIFY_IME_OF_FOCUS
+    // yet since NOTIFY_IME_OF_FOCUS will be sent to widget asynchronously.
+    // So, we need to do nothing here.  After NOTIFY_IME_OF_FOCUS has been
+    // sent, OnIMEReceivedFocus() will be called and content, selection and/or
+    // position changes will be observed
+    return;
+  }
+
+  // When this is called after editor reframing (i.e., the root editable node
+  // is also recreated), IME has usually received NOTIFY_IME_OF_FOCUS.  In this
+  // case, we need to restart to observe content, selection and/or position
+  // changes in new root editable node.
+  ObserveEditableNode();
+
+  if (!NeedsToNotifyIMEOfSomething()) {
+    return;
+  }
+
+  // Some change events may wait to notify IME because this was being
+  // initialized.  It is the time to flush them.
+  FlushMergeableNotifications();
+}
+
+void
+IMEContentObserver::OnIMEReceivedFocus()
+{
+  // While Init() notifies IME of focus, pending layout may be flushed
+  // because the notification may cause querying content.  Then, recursive
+  // call of Init() with the latest content may occur.  In such case, we
+  // shouldn't keep first initialization which notified IME of focus.
+  if (GetState() != eState_Initializing) {
+    return;
+  }
+
+  // NOTIFY_IME_OF_FOCUS might cause recreating IMEContentObserver
+  // instance via IMEStateManager::UpdateIMEState().  So, this
+  // instance might already have been destroyed, check it.
+  if (!mRootContent) {
+    return;
+  }
+
+  // Start to observe which is needed by IME when IME actually has focus.
+  ObserveEditableNode();
+
+  if (!NeedsToNotifyIMEOfSomething()) {
+    return;
+  }
+
+  // Some change events may wait to notify IME because this was being
+  // initialized.  It is the time to flush them.
+  FlushMergeableNotifications();
+}
+
+bool
+IMEContentObserver::InitWithEditor(nsPresContext* aPresContext,
+                                   nsIContent* aContent,
+                                   nsIEditor* aEditor)
+{
+  MOZ_ASSERT(aEditor);
+
+  mEditableNode =
+    IMEStateManager::GetRootEditableNode(aPresContext, aContent);
+  if (NS_WARN_IF(!mEditableNode)) {
+    return false;
+  }
+
+  mEditor = aEditor;
+  if (NS_WARN_IF(!mEditor)) {
+    return false;
+  }
+
+  nsIPresShell* presShell = aPresContext->PresShell();
+
+  // get selection and root content
+  nsCOMPtr<nsISelectionController> selCon;
+  if (mEditableNode->IsNodeOfType(nsINode::eCONTENT)) {
+    nsIFrame* frame =
+      static_cast<nsIContent*>(mEditableNode.get())->GetPrimaryFrame();
+    if (NS_WARN_IF(!frame)) {
+      return false;
+    }
+
+    frame->GetSelectionController(aPresContext,
+                                  getter_AddRefs(selCon));
+  } else {
+    // mEditableNode is a document
+    selCon = do_QueryInterface(presShell);
+  }
+
+  if (NS_WARN_IF(!selCon)) {
+    return false;
+  }
+
+  selCon->GetSelection(nsISelectionController::SELECTION_NORMAL,
+                       getter_AddRefs(mSelection));
+  if (NS_WARN_IF(!mSelection)) {
+    return false;
+  }
+
+  nsCOMPtr<nsIDOMRange> selDomRange;
+  if (NS_SUCCEEDED(mSelection->GetRangeAt(0, getter_AddRefs(selDomRange)))) {
+    nsRange* selRange = static_cast<nsRange*>(selDomRange.get());
+    if (NS_WARN_IF(!selRange) || NS_WARN_IF(!selRange->GetStartParent())) {
+      return false;
+    }
+
+    mRootContent = selRange->GetStartParent()->
+                     GetSelectionRootContent(presShell);
+  } else {
+    mRootContent = mEditableNode->GetSelectionRootContent(presShell);
+  }
+  if (!mRootContent && mEditableNode->IsNodeOfType(nsINode::eDOCUMENT)) {
+    // The document node is editable, but there are no contents, this document
+    // is not editable.
+    return false;
+  }
+
+  if (NS_WARN_IF(!mRootContent)) {
+    return false;
+  }
+
+  mDocShell = aPresContext->GetDocShell();
+  if (NS_WARN_IF(!mDocShell)) {
+    return false;
+  }
+
+  MOZ_ASSERT(!WasInitializedWithPlugin());
+
+  return true;
+}
+
+bool
+IMEContentObserver::InitWithPlugin(nsPresContext* aPresContext,
+                                   nsIContent* aContent)
+{
+  if (NS_WARN_IF(!aContent) ||
+      NS_WARN_IF(aContent->GetDesiredIMEState().mEnabled != IMEState::PLUGIN)) {
+    return false;
+  }
+  nsIFrame* frame = aContent->GetPrimaryFrame();
+  if (NS_WARN_IF(!frame)) {
+    return false;
+  }
+  nsCOMPtr<nsISelectionController> selCon;
+  frame->GetSelectionController(aPresContext, getter_AddRefs(selCon));
+  if (NS_WARN_IF(!selCon)) {
+    return false;
+  }
+  selCon->GetSelection(nsISelectionController::SELECTION_NORMAL,
+                       getter_AddRefs(mSelection));
+  if (NS_WARN_IF(!mSelection)) {
+    return false;
+  }
+
+  mEditor = nullptr;
+  mEditableNode = aContent;
+  mRootContent = aContent;
+
+  mDocShell = aPresContext->GetDocShell();
+  if (NS_WARN_IF(!mDocShell)) {
+    return false;
+  }
+
+  MOZ_ASSERT(WasInitializedWithPlugin());
+
+  return true;
+}
+
+bool
+IMEContentObserver::WasInitializedWithPlugin() const
+{
+  return mDocShell && !mEditor;
+}
+
+void
+IMEContentObserver::Clear()
+{
+  mEditor = nullptr;
+  mSelection = nullptr;
+  mEditableNode = nullptr;
+  mRootContent = nullptr;
+  mDocShell = nullptr;
+}
+
+void
+IMEContentObserver::ObserveEditableNode()
+{
+  MOZ_RELEASE_ASSERT(mSelection);
+  MOZ_RELEASE_ASSERT(mRootContent);
+  MOZ_RELEASE_ASSERT(GetState() != eState_Observing);
+
+  // If this is called before sending NOTIFY_IME_OF_FOCUS (it's possible when
+  // the editor is reframed before sending NOTIFY_IME_OF_FOCUS asynchronously),
+  // the update preference of mWidget may be different from after the widget
+  // receives NOTIFY_IME_OF_FOCUS.   So, this should be called again by
+  // OnIMEReceivedFocus() which is called after sending NOTIFY_IME_OF_FOCUS.
+  if (!mIMEHasFocus) {
+    MOZ_ASSERT(!mWidget || mNeedsToNotifyIMEOfFocusSet ||
+               mSendingNotification == NOTIFY_IME_OF_FOCUS,
+               "Wow, OnIMEReceivedFocus() won't be called?");
+    return;
+  }
+
+  mIsObserving = true;
+  if (mEditor) {
+    mEditor->AddEditorObserver(this);
+  }
+
+  mUpdatePreference = mWidget->GetIMEUpdatePreference();
+  if (!WasInitializedWithPlugin()) {
+    // Add selection change listener only when this starts to observe
+    // non-plugin content since we cannot detect selection changes in
+    // plugins.
+    nsCOMPtr<nsISelectionPrivate> selPrivate(do_QueryInterface(mSelection));
+    NS_ENSURE_TRUE_VOID(selPrivate);
+    nsresult rv = selPrivate->AddSelectionListener(this);
+    NS_ENSURE_SUCCESS_VOID(rv);
+  }
+
+  if (mUpdatePreference.WantTextChange()) {
+    // add text change observer
+    mRootContent->AddMutationObserver(this);
+  }
+
+  if (mUpdatePreference.WantPositionChanged() && mDocShell) {
+    // Add scroll position listener and reflow observer to detect position and
+    // size changes
+    mDocShell->AddWeakScrollObserver(this);
+    mDocShell->AddWeakReflowObserver(this);
+  }
+}
+
+void
+IMEContentObserver::NotifyIMEOfBlur()
+{
+  // Prevent any notifications to be sent IME.
+  nsCOMPtr<nsIWidget> widget;
+  mWidget.swap(widget);
+
+  // If we hasn't been set focus, we shouldn't send blur notification to IME.
+  if (!mIMEHasFocus) {
+    return;
+  }
+
+  // mWidget must have been non-nullptr if IME has focus.
+  MOZ_RELEASE_ASSERT(widget);
+
+  RefPtr<IMEContentObserver> kungFuDeathGrip(this);
+
+  MOZ_LOG(sIMECOLog, LogLevel::Info,
+    ("0x%p IMEContentObserver::NotifyIMEOfBlur(), "
+     "sending NOTIFY_IME_OF_BLUR", this));
+
+  // For now, we need to send blur notification in any condition because
+  // we don't have any simple ways to send blur notification asynchronously.
+  // After this call, Destroy() or Unlink() will stop observing the content
+  // and forget everything.  Therefore, if it's not safe to send notification
+  // when script blocker is unlocked, we cannot send blur notification after
+  // that and before next focus notification.
+  // Anyway, as far as we know, IME doesn't try to query content when it loses
+  // focus.  So, this may not cause any problem.
+  mIMEHasFocus = false;
+  IMEStateManager::NotifyIME(IMENotification(NOTIFY_IME_OF_BLUR), widget);
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::NotifyIMEOfBlur(), "
+     "sent NOTIFY_IME_OF_BLUR", this));
+}
+
+void
+IMEContentObserver::UnregisterObservers()
+{
+  if (!mIsObserving) {
+    return;
+  }
+  mIsObserving = false;
+
+  if (mEditor) {
+    mEditor->RemoveEditorObserver(this);
+  }
+
+  if (mSelection) {
+    nsCOMPtr<nsISelectionPrivate> selPrivate(do_QueryInterface(mSelection));
+    if (selPrivate) {
+      selPrivate->RemoveSelectionListener(this);
+    }
+    mSelectionData.Clear();
+    mFocusedWidget = nullptr;
+  }
+
+  if (mUpdatePreference.WantTextChange() && mRootContent) {
+    mRootContent->RemoveMutationObserver(this);
+  }
+
+  if (mUpdatePreference.WantPositionChanged() && mDocShell) {
+    mDocShell->RemoveWeakScrollObserver(this);
+    mDocShell->RemoveWeakReflowObserver(this);
+  }
+}
+
+nsPresContext*
+IMEContentObserver::GetPresContext() const
+{
+  return mESM ? mESM->GetPresContext() : nullptr;
+}
+
+void
+IMEContentObserver::Destroy()
+{
+  // WARNING: When you change this method, you have to check Unlink() too.
+
+  NotifyIMEOfBlur();
+  UnregisterObservers();
+  Clear();
+
+  mWidget = nullptr;
+  mUpdatePreference.mWantUpdates = nsIMEUpdatePreference::NOTIFY_NOTHING;
+
+  if (mESM) {
+    mESM->OnStopObservingContent(this);
+    mESM = nullptr;
+  }
+}
+
+bool
+IMEContentObserver::Destroyed() const
+{
+  return !mWidget;
+}
+
+void
+IMEContentObserver::DisconnectFromEventStateManager()
+{
+  mESM = nullptr;
+}
+
+bool
+IMEContentObserver::MaybeReinitialize(nsIWidget* aWidget,
+                                      nsPresContext* aPresContext,
+                                      nsIContent* aContent,
+                                      nsIEditor* aEditor)
+{
+  if (!IsObservingContent(aPresContext, aContent)) {
+    return false;
+  }
+
+  if (GetState() == eState_StoppedObserving) {
+    Init(aWidget, aPresContext, aContent, aEditor);
+  }
+  return IsManaging(aPresContext, aContent);
+}
+
+bool
+IMEContentObserver::IsManaging(nsPresContext* aPresContext,
+                               nsIContent* aContent) const
+{
+  return GetState() == eState_Observing &&
+         IsObservingContent(aPresContext, aContent);
+}
+
+bool
+IMEContentObserver::IsManaging(const TextComposition* aComposition) const
+{
+  if (GetState() != eState_Observing) {
+    return false;
+  }
+  nsPresContext* presContext = aComposition->GetPresContext();
+  if (NS_WARN_IF(!presContext)) {
+    return false;
+  }
+  if (presContext != GetPresContext()) {
+    return false; // observing different document
+  }
+  nsINode* targetNode = aComposition->GetEventTargetNode();
+  nsIContent* targetContent =
+    targetNode && targetNode->IsContent() ? targetNode->AsContent() : nullptr;
+  return IsObservingContent(presContext, targetContent);
+}
+
+IMEContentObserver::State
+IMEContentObserver::GetState() const
+{
+  if (!mSelection || !mRootContent || !mEditableNode) {
+    return eState_NotObserving; // failed to initialize or finalized.
+  }
+  if (!mRootContent->IsInComposedDoc()) {
+    // the focused editor has already been reframed.
+    return eState_StoppedObserving;
+  }
+  return mIsObserving ? eState_Observing : eState_Initializing;
+}
+
+bool
+IMEContentObserver::IsObservingContent(nsPresContext* aPresContext,
+                                       nsIContent* aContent) const
+{
+  return IsInitializedWithPlugin() ?
+    mRootContent == aContent && mRootContent != nullptr :
+    mEditableNode == IMEStateManager::GetRootEditableNode(aPresContext,
+                                                          aContent);
+}
+
+bool
+IMEContentObserver::IsEditorHandlingEventForComposition() const
+{
+  if (!mWidget) {
+    return false;
+  }
+  RefPtr<TextComposition> composition =
+    IMEStateManager::GetTextCompositionFor(mWidget);
+  if (!composition) {
+    return false;
+  }
+  return composition->IsEditorHandlingEvent();
+}
+
+bool
+IMEContentObserver::IsEditorComposing() const
+{
+  // Note that don't use TextComposition here. The important thing is,
+  // whether the editor already started to handle composition because
+  // web contents can change selection, text content and/or something from
+  // compositionstart event listener which is run before EditorBase handles it.
+  nsCOMPtr<nsIEditorIMESupport> editorIMESupport = do_QueryInterface(mEditor);
+  if (NS_WARN_IF(!editorIMESupport)) {
+    return false;
+  }
+  bool isComposing = false;
+  nsresult rv = editorIMESupport->GetComposing(&isComposing);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return false;
+  }
+  return isComposing;
+}
+
+nsresult
+IMEContentObserver::GetSelectionAndRoot(nsISelection** aSelection,
+                                        nsIContent** aRootContent) const
+{
+  if (!mEditableNode || !mSelection) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  NS_ASSERTION(mSelection && mRootContent, "uninitialized content observer");
+  NS_ADDREF(*aSelection = mSelection);
+  NS_ADDREF(*aRootContent = mRootContent);
+  return NS_OK;
+}
+
+nsresult
+IMEContentObserver::NotifySelectionChanged(nsIDOMDocument* aDOMDocument,
+                                           nsISelection* aSelection,
+                                           int16_t aReason)
+{
+  int32_t count = 0;
+  nsresult rv = aSelection->GetRangeCount(&count);
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (count > 0 && mWidget) {
+    bool causedByComposition = IsEditorHandlingEventForComposition();
+    bool causedBySelectionEvent = TextComposition::IsHandlingSelectionEvent();
+    bool duringComposition = IsEditorComposing();
+    MaybeNotifyIMEOfSelectionChange(causedByComposition,
+                                    causedBySelectionEvent,
+                                    duringComposition);
+  }
+  return NS_OK;
+}
+
+void
+IMEContentObserver::ScrollPositionChanged()
+{
+  MaybeNotifyIMEOfPositionChange();
+}
+
+NS_IMETHODIMP
+IMEContentObserver::Reflow(DOMHighResTimeStamp aStart,
+                           DOMHighResTimeStamp aEnd)
+{
+  MaybeNotifyIMEOfPositionChange();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+IMEContentObserver::ReflowInterruptible(DOMHighResTimeStamp aStart,
+                                        DOMHighResTimeStamp aEnd)
+{
+  MaybeNotifyIMEOfPositionChange();
+  return NS_OK;
+}
+
+nsresult
+IMEContentObserver::HandleQueryContentEvent(WidgetQueryContentEvent* aEvent)
+{
+  // If the instance has normal selection cache and the query event queries
+  // normal selection's range, it should use the cached selection which was
+  // sent to the widget.  However, if this instance has already received new
+  // selection change notification but hasn't updated the cache yet (i.e.,
+  // not sending selection change notification to IME, don't use the cached
+  // value.  Note that don't update selection cache here since if you update
+  // selection cache here, IMENotificationSender won't notify IME of selection
+  // change because it looks like that the selection isn't actually changed.
+  bool isSelectionCacheAvailable =
+    aEvent->mUseNativeLineBreak && mSelectionData.IsValid() &&
+    !mNeedsToNotifyIMEOfSelectionChange;
+  if (isSelectionCacheAvailable &&
+      aEvent->mMessage == eQuerySelectedText &&
+      aEvent->mInput.mSelectionType == SelectionType::eNormal) {
+    aEvent->mReply.mContentsRoot = mRootContent;
+    aEvent->mReply.mHasSelection = !mSelectionData.IsCollapsed();
+    aEvent->mReply.mOffset = mSelectionData.mOffset;
+    aEvent->mReply.mString = mSelectionData.String();
+    aEvent->mReply.mWritingMode = mSelectionData.GetWritingMode();
+    aEvent->mReply.mReversed = mSelectionData.mReversed;
+    aEvent->mSucceeded = true;
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p IMEContentObserver::HandleQueryContentEvent(aEvent={ "
+       "mMessage=%s })", this, ToChar(aEvent->mMessage)));
+    return NS_OK;
+  }
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::HandleQueryContentEvent(aEvent={ "
+     "mMessage=%s })", this, ToChar(aEvent->mMessage)));
+
+  // If we can make the event's input offset absolute with TextComposition or
+  // mSelection, we should set it here for reducing the cost of computing
+  // selection start offset.  If ContentEventHandler receives a
+  // WidgetQueryContentEvent whose input offset is relative to insertion point,
+  // it computes current selection start offset (this may be expensive) and
+  // make the offset absolute value itself.
+  // Note that calling MakeOffsetAbsolute() makes the event a query event with
+  // absolute offset.  So, ContentEventHandler doesn't pay any additional cost
+  // after calling MakeOffsetAbsolute() here.
+  if (aEvent->mInput.mRelativeToInsertionPoint &&
+      aEvent->mInput.IsValidEventMessage(aEvent->mMessage)) {
+    RefPtr<TextComposition> composition =
+      IMEStateManager::GetTextCompositionFor(aEvent->mWidget);
+    if (composition) {
+      uint32_t compositionStart = composition->NativeOffsetOfStartComposition();
+      if (NS_WARN_IF(!aEvent->mInput.MakeOffsetAbsolute(compositionStart))) {
+        return NS_ERROR_FAILURE;
+      }
+    } else if (isSelectionCacheAvailable) {
+      uint32_t selectionStart = mSelectionData.mOffset;
+      if (NS_WARN_IF(!aEvent->mInput.MakeOffsetAbsolute(selectionStart))) {
+        return NS_ERROR_FAILURE;
+      }
+    }
+  }
+
+  AutoRestore<bool> handling(mIsHandlingQueryContentEvent);
+  mIsHandlingQueryContentEvent = true;
+  ContentEventHandler handler(GetPresContext());
+  nsresult rv = handler.HandleQueryContentEvent(aEvent);
+  if (NS_WARN_IF(Destroyed())) {
+    // If this has already destroyed during querying the content, the query
+    // is outdated even if it's succeeded.  So, make the query fail.
+    aEvent->mSucceeded = false;
+    MOZ_LOG(sIMECOLog, LogLevel::Warning,
+      ("0x%p IMEContentObserver::HandleQueryContentEvent(), WARNING, "
+       "IMEContentObserver has been destroyed during the query, "
+       "making the query fail", this));
+    return rv;
+  }
+
+  if (!IsInitializedWithPlugin() &&
+      NS_WARN_IF(aEvent->mReply.mContentsRoot != mRootContent)) {
+    // Focus has changed unexpectedly, so make the query fail.
+    aEvent->mSucceeded = false;
+  }
+  return rv;
+}
+
+bool
+IMEContentObserver::OnMouseButtonEvent(nsPresContext* aPresContext,
+                                       WidgetMouseEvent* aMouseEvent)
+{
+  if (!mUpdatePreference.WantMouseButtonEventOnChar()) {
+    return false;
+  }
+  if (!aMouseEvent->IsTrusted() ||
+      aMouseEvent->DefaultPrevented() ||
+      !aMouseEvent->mWidget) {
+    return false;
+  }
+  // Now, we need to notify only mouse down and mouse up event.
+  switch (aMouseEvent->mMessage) {
+    case eMouseUp:
+    case eMouseDown:
+      break;
+    default:
+      return false;
+  }
+  if (NS_WARN_IF(!mWidget) || NS_WARN_IF(mWidget->Destroyed())) {
+    return false;
+  }
+
+  RefPtr<IMEContentObserver> kungFuDeathGrip(this);
+
+  WidgetQueryContentEvent charAtPt(true, eQueryCharacterAtPoint,
+                                   aMouseEvent->mWidget);
+  charAtPt.mRefPoint = aMouseEvent->mRefPoint;
+  ContentEventHandler handler(aPresContext);
+  handler.OnQueryCharacterAtPoint(&charAtPt);
+  if (NS_WARN_IF(!charAtPt.mSucceeded) ||
+      charAtPt.mReply.mOffset == WidgetQueryContentEvent::NOT_FOUND) {
+    return false;
+  }
+
+  // The widget might be destroyed during querying the content since it
+  // causes flushing layout.
+  if (!mWidget || NS_WARN_IF(mWidget->Destroyed())) {
+    return false;
+  }
+
+  // The result character rect is relative to the top level widget.
+  // We should notify it with offset in the widget.
+  nsIWidget* topLevelWidget = mWidget->GetTopLevelWidget();
+  if (topLevelWidget && topLevelWidget != mWidget) {
+    charAtPt.mReply.mRect.MoveBy(
+      topLevelWidget->WidgetToScreenOffset() -
+        mWidget->WidgetToScreenOffset());
+  }
+  // The refPt is relative to its widget.
+  // We should notify it with offset in the widget.
+  if (aMouseEvent->mWidget != mWidget) {
+    charAtPt.mRefPoint += aMouseEvent->mWidget->WidgetToScreenOffset() -
+      mWidget->WidgetToScreenOffset();
+  }
+
+  IMENotification notification(NOTIFY_IME_OF_MOUSE_BUTTON_EVENT);
+  notification.mMouseButtonEventData.mEventMessage = aMouseEvent->mMessage;
+  notification.mMouseButtonEventData.mOffset = charAtPt.mReply.mOffset;
+  notification.mMouseButtonEventData.mCursorPos.Set(
+    charAtPt.mRefPoint.ToUnknownPoint());
+  notification.mMouseButtonEventData.mCharRect.Set(
+    charAtPt.mReply.mRect.ToUnknownRect());
+  notification.mMouseButtonEventData.mButton = aMouseEvent->button;
+  notification.mMouseButtonEventData.mButtons = aMouseEvent->buttons;
+  notification.mMouseButtonEventData.mModifiers = aMouseEvent->mModifiers;
+
+  nsresult rv = IMEStateManager::NotifyIME(notification, mWidget);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return false;
+  }
+
+  bool consumed = (rv == NS_SUCCESS_EVENT_CONSUMED);
+  if (consumed) {
+    aMouseEvent->PreventDefault();
+  }
+  return consumed;
+}
+
+void
+IMEContentObserver::CharacterDataWillChange(nsIDocument* aDocument,
+                                            nsIContent* aContent,
+                                            CharacterDataChangeInfo* aInfo)
+{
+  NS_ASSERTION(aContent->IsNodeOfType(nsINode::eTEXT),
+               "character data changed for non-text node");
+  MOZ_ASSERT(mPreCharacterDataChangeLength < 0,
+             "CharacterDataChanged() should've reset "
+             "mPreCharacterDataChangeLength");
+
+  mEndOfAddedTextCache.Clear();
+  mStartOfRemovingTextRangeCache.Clear();
+  mPreCharacterDataChangeLength =
+    ContentEventHandler::GetNativeTextLength(aContent, aInfo->mChangeStart,
+                                             aInfo->mChangeEnd);
+  MOZ_ASSERT(mPreCharacterDataChangeLength >=
+               aInfo->mChangeEnd - aInfo->mChangeStart,
+             "The computed length must be same as or larger than XP length");
+}
+
+void
+IMEContentObserver::CharacterDataChanged(nsIDocument* aDocument,
+                                         nsIContent* aContent,
+                                         CharacterDataChangeInfo* aInfo)
+{
+  NS_ASSERTION(aContent->IsNodeOfType(nsINode::eTEXT),
+               "character data changed for non-text node");
+
+  mEndOfAddedTextCache.Clear();
+  mStartOfRemovingTextRangeCache.Clear();
+
+  int64_t removedLength = mPreCharacterDataChangeLength;
+  mPreCharacterDataChangeLength = -1;
+
+  MOZ_ASSERT(removedLength >= 0,
+             "mPreCharacterDataChangeLength should've been set by "
+             "CharacterDataWillChange()");
+
+  uint32_t offset = 0;
+  // get offsets of change and fire notification
+  nsresult rv =
+    ContentEventHandler::GetFlatTextLengthInRange(
+                           NodePosition(mRootContent, 0),
+                           NodePosition(aContent, aInfo->mChangeStart),
+                           mRootContent, &offset, LINE_BREAK_TYPE_NATIVE);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return;
+  }
+
+  uint32_t newLength =
+    ContentEventHandler::GetNativeTextLength(aContent, aInfo->mChangeStart,
+                                             aInfo->mChangeStart +
+                                               aInfo->mReplaceLength);
+
+  uint32_t oldEnd = offset + static_cast<uint32_t>(removedLength);
+  uint32_t newEnd = offset + newLength;
+
+  TextChangeData data(offset, oldEnd, newEnd,
+                      IsEditorHandlingEventForComposition(),
+                      IsEditorComposing());
+  MaybeNotifyIMEOfTextChange(data);
+}
+
+void
+IMEContentObserver::NotifyContentAdded(nsINode* aContainer,
+                                       int32_t aStartIndex,
+                                       int32_t aEndIndex)
+{
+  mStartOfRemovingTextRangeCache.Clear();
+
+  uint32_t offset = 0;
+  nsresult rv = NS_OK;
+  if (!mEndOfAddedTextCache.Match(aContainer, aStartIndex)) {
+    mEndOfAddedTextCache.Clear();
+    rv = ContentEventHandler::GetFlatTextLengthInRange(
+                                NodePosition(mRootContent, 0),
+                                NodePositionBefore(aContainer, aStartIndex),
+                                mRootContent, &offset, LINE_BREAK_TYPE_NATIVE);
+    if (NS_WARN_IF(NS_FAILED((rv)))) {
+      return;
+    }
+  } else {
+    offset = mEndOfAddedTextCache.mFlatTextLength;
+  }
+
+  // get offset at the end of the last added node
+  uint32_t addingLength = 0;
+  rv = ContentEventHandler::GetFlatTextLengthInRange(
+                              NodePositionBefore(aContainer, aStartIndex),
+                              NodePosition(aContainer, aEndIndex),
+                              mRootContent, &addingLength,
+                              LINE_BREAK_TYPE_NATIVE);
+  if (NS_WARN_IF(NS_FAILED((rv)))) {
+    mEndOfAddedTextCache.Clear();
+    return;
+  }
+
+  // If multiple lines are being inserted in an HTML editor, next call of
+  // NotifyContentAdded() is for adding next node.  Therefore, caching the text
+  // length can skip to compute the text length before the adding node and
+  // before of it.
+  mEndOfAddedTextCache.Cache(aContainer, aEndIndex, offset + addingLength);
+
+  if (!addingLength) {
+    return;
+  }
+
+  TextChangeData data(offset, offset, offset + addingLength,
+                      IsEditorHandlingEventForComposition(),
+                      IsEditorComposing());
+  MaybeNotifyIMEOfTextChange(data);
+}
+
+void
+IMEContentObserver::ContentAppended(nsIDocument* aDocument,
+                                    nsIContent* aContainer,
+                                    nsIContent* aFirstNewContent,
+                                    int32_t aNewIndexInContainer)
+{
+  NotifyContentAdded(aContainer, aNewIndexInContainer,
+                     aContainer->GetChildCount());
+}
+
+void
+IMEContentObserver::ContentInserted(nsIDocument* aDocument,
+                                    nsIContent* aContainer,
+                                    nsIContent* aChild,
+                                    int32_t aIndexInContainer)
+{
+  NotifyContentAdded(NODE_FROM(aContainer, aDocument),
+                     aIndexInContainer, aIndexInContainer + 1);
+}
+
+void
+IMEContentObserver::ContentRemoved(nsIDocument* aDocument,
+                                   nsIContent* aContainer,
+                                   nsIContent* aChild,
+                                   int32_t aIndexInContainer,
+                                   nsIContent* aPreviousSibling)
+{
+  mEndOfAddedTextCache.Clear();
+
+  nsINode* containerNode = NODE_FROM(aContainer, aDocument);
+
+  uint32_t offset = 0;
+  nsresult rv = NS_OK;
+  if (!mStartOfRemovingTextRangeCache.Match(containerNode, aIndexInContainer)) {
+    // At removing a child node of aContainer, we need the line break caused
+    // by open tag of aContainer.  Be careful when aIndexInContainer is 0.
+    rv = ContentEventHandler::GetFlatTextLengthInRange(
+                                NodePosition(mRootContent, 0),
+                                NodePosition(containerNode, aIndexInContainer),
+                                mRootContent, &offset, LINE_BREAK_TYPE_NATIVE);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      mStartOfRemovingTextRangeCache.Clear();
+      return;
+    }
+    mStartOfRemovingTextRangeCache.Cache(containerNode, aIndexInContainer,
+                                         offset);
+  } else {
+    offset = mStartOfRemovingTextRangeCache.mFlatTextLength;
+  }
+
+  // get offset at the end of the deleted node
+  uint32_t textLength = 0;
+  if (aChild->IsNodeOfType(nsINode::eTEXT)) {
+    textLength = ContentEventHandler::GetNativeTextLength(aChild);
+  } else {
+    uint32_t nodeLength = static_cast<int32_t>(aChild->GetChildCount());
+    rv = ContentEventHandler::GetFlatTextLengthInRange(
+                                NodePositionBefore(aChild, 0),
+                                NodePosition(aChild, nodeLength),
+                                mRootContent, &textLength,
+                                LINE_BREAK_TYPE_NATIVE, true);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      mStartOfRemovingTextRangeCache.Clear();
+      return;
+    }
+  }
+
+  if (!textLength) {
+    return;
+  }
+
+  TextChangeData data(offset, offset + textLength, offset,
+                      IsEditorHandlingEventForComposition(),
+                      IsEditorComposing());
+  MaybeNotifyIMEOfTextChange(data);
+}
+
+void
+IMEContentObserver::AttributeWillChange(nsIDocument* aDocument,
+                                        dom::Element* aElement,
+                                        int32_t aNameSpaceID,
+                                        nsIAtom* aAttribute,
+                                        int32_t aModType,
+                                        const nsAttrValue* aNewValue)
+{
+  mPreAttrChangeLength =
+    ContentEventHandler::GetNativeTextLengthBefore(aElement, mRootContent);
+}
+
+void
+IMEContentObserver::AttributeChanged(nsIDocument* aDocument,
+                                     dom::Element* aElement,
+                                     int32_t aNameSpaceID,
+                                     nsIAtom* aAttribute,
+                                     int32_t aModType,
+                                     const nsAttrValue* aOldValue)
+{
+  mEndOfAddedTextCache.Clear();
+  mStartOfRemovingTextRangeCache.Clear();
+
+  uint32_t postAttrChangeLength =
+    ContentEventHandler::GetNativeTextLengthBefore(aElement, mRootContent);
+  if (postAttrChangeLength == mPreAttrChangeLength) {
+    return;
+  }
+  uint32_t start;
+  nsresult rv =
+    ContentEventHandler::GetFlatTextLengthInRange(
+                           NodePosition(mRootContent, 0),
+                           NodePositionBefore(aElement, 0),
+                           mRootContent, &start, LINE_BREAK_TYPE_NATIVE);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return;
+  }
+
+  TextChangeData data(start, start + mPreAttrChangeLength,
+                      start + postAttrChangeLength,
+                      IsEditorHandlingEventForComposition(),
+                      IsEditorComposing());
+  MaybeNotifyIMEOfTextChange(data);
+}
+
+void
+IMEContentObserver::SuppressNotifyingIME()
+{
+  mSuppressNotifications++;
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::SuppressNotifyingIME(), "
+     "mSuppressNotifications=%u", this, mSuppressNotifications));
+}
+
+void
+IMEContentObserver::UnsuppressNotifyingIME()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::UnsuppressNotifyingIME(), "
+     "mSuppressNotifications=%u", this, mSuppressNotifications));
+
+  if (!mSuppressNotifications || --mSuppressNotifications) {
+    return;
+  }
+  FlushMergeableNotifications();
+}
+
+NS_IMETHODIMP
+IMEContentObserver::EditAction()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::EditAction()", this));
+
+  mEndOfAddedTextCache.Clear();
+  mStartOfRemovingTextRangeCache.Clear();
+  FlushMergeableNotifications();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+IMEContentObserver::BeforeEditAction()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::BeforeEditAction()", this));
+
+  mEndOfAddedTextCache.Clear();
+  mStartOfRemovingTextRangeCache.Clear();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+IMEContentObserver::CancelEditAction()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::CancelEditAction()", this));
+
+  mEndOfAddedTextCache.Clear();
+  mStartOfRemovingTextRangeCache.Clear();
+  FlushMergeableNotifications();
+  return NS_OK;
+}
+
+void
+IMEContentObserver::PostFocusSetNotification()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::PostFocusSetNotification()", this));
+
+  mNeedsToNotifyIMEOfFocusSet = true;
+}
+
+void
+IMEContentObserver::PostTextChangeNotification()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::PostTextChangeNotification("
+     "mTextChangeData=%s)",
+     this, TextChangeDataToString(mTextChangeData).get()));
+
+  MOZ_ASSERT(mTextChangeData.IsValid(),
+             "mTextChangeData must have text change data");
+  mNeedsToNotifyIMEOfTextChange = true;
+}
+
+void
+IMEContentObserver::PostSelectionChangeNotification()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::PostSelectionChangeNotification(), "
+     "mSelectionData={ mCausedByComposition=%s, mCausedBySelectionEvent=%s }",
+     this, ToChar(mSelectionData.mCausedByComposition),
+     ToChar(mSelectionData.mCausedBySelectionEvent)));
+
+  mNeedsToNotifyIMEOfSelectionChange = true;
+}
+
+void
+IMEContentObserver::MaybeNotifyIMEOfFocusSet()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::MaybeNotifyIMEOfFocusSet()", this));
+
+  PostFocusSetNotification();
+  FlushMergeableNotifications();
+}
+
+void
+IMEContentObserver::MaybeNotifyIMEOfTextChange(
+                      const TextChangeDataBase& aTextChangeData)
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::MaybeNotifyIMEOfTextChange("
+     "aTextChangeData=%s)",
+     this, TextChangeDataToString(aTextChangeData).get()));
+
+  mTextChangeData += aTextChangeData;
+  PostTextChangeNotification();
+  FlushMergeableNotifications();
+}
+
+void
+IMEContentObserver::MaybeNotifyIMEOfSelectionChange(
+                      bool aCausedByComposition,
+                      bool aCausedBySelectionEvent,
+                      bool aOccurredDuringComposition)
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::MaybeNotifyIMEOfSelectionChange("
+     "aCausedByComposition=%s, aCausedBySelectionEvent=%s, "
+     "aOccurredDuringComposition)",
+     this, ToChar(aCausedByComposition), ToChar(aCausedBySelectionEvent)));
+
+  mSelectionData.AssignReason(aCausedByComposition,
+                              aCausedBySelectionEvent,
+                              aOccurredDuringComposition);
+  PostSelectionChangeNotification();
+  FlushMergeableNotifications();
+}
+
+void
+IMEContentObserver::MaybeNotifyIMEOfPositionChange()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::MaybeNotifyIMEOfPositionChange()", this));
+  // If reflow is caused by ContentEventHandler during PositionChangeEvent
+  // sending NOTIFY_IME_OF_POSITION_CHANGE, we don't need to notify IME of it
+  // again since ContentEventHandler returns the result including this reflow's
+  // result.
+  if (mIsHandlingQueryContentEvent &&
+      mSendingNotification == NOTIFY_IME_OF_POSITION_CHANGE) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p   IMEContentObserver::MaybeNotifyIMEOfPositionChange(), "
+       "ignored since caused by ContentEventHandler during sending "
+       "NOTIY_IME_OF_POSITION_CHANGE", this));
+    return;
+  }
+  PostPositionChangeNotification();
+  FlushMergeableNotifications();
+}
+
+void
+IMEContentObserver::MaybeNotifyCompositionEventHandled()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::MaybeNotifyCompositionEventHandled()",
+     this));
+
+  PostCompositionEventHandledNotification();
+  FlushMergeableNotifications();
+}
+
+bool
+IMEContentObserver::UpdateSelectionCache()
+{
+  MOZ_ASSERT(IsSafeToNotifyIME());
+
+  if (WasInitializedWithPlugin()) {
+    return false;
+  }
+
+  mSelectionData.ClearSelectionData();
+
+  // XXX Cannot we cache some information for reducing the cost to compute
+  //     selection offset and writing mode?
+  WidgetQueryContentEvent selection(true, eQuerySelectedText, mWidget);
+  ContentEventHandler handler(GetPresContext());
+  handler.OnQuerySelectedText(&selection);
+  if (NS_WARN_IF(!selection.mSucceeded) ||
+      NS_WARN_IF(selection.mReply.mContentsRoot != mRootContent)) {
+    return false;
+  }
+
+  mFocusedWidget = selection.mReply.mFocusedWidget;
+  mSelectionData.mOffset = selection.mReply.mOffset;
+  *mSelectionData.mString = selection.mReply.mString;
+  mSelectionData.SetWritingMode(selection.GetWritingMode());
+  mSelectionData.mReversed = selection.mReply.mReversed;
+
+  // WARNING: Don't modify the reason of selection change here.
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::UpdateSelectionCache(), "
+     "mSelectionData=%s",
+     this, SelectionChangeDataToString(mSelectionData).get()));
+
+  return mSelectionData.IsValid();
+}
+
+void
+IMEContentObserver::PostPositionChangeNotification()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::PostPositionChangeNotification()", this));
+
+  mNeedsToNotifyIMEOfPositionChange = true;
+}
+
+void
+IMEContentObserver::PostCompositionEventHandledNotification()
+{
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::"
+     "PostCompositionEventHandledNotification()", this));
+
+  mNeedsToNotifyIMEOfCompositionEventHandled = true;
+}
+
+bool
+IMEContentObserver::IsReflowLocked() const
+{
+  nsPresContext* presContext = GetPresContext();
+  if (NS_WARN_IF(!presContext)) {
+    return false;
+  }
+  nsIPresShell* presShell = presContext->GetPresShell();
+  if (NS_WARN_IF(!presShell)) {
+    return false;
+  }
+  // During reflow, we shouldn't notify IME because IME may query content
+  // synchronously.  Then, it causes ContentEventHandler will try to flush
+  // pending notifications during reflow.
+  return presShell->IsReflowLocked();
+}
+
+bool
+IMEContentObserver::IsSafeToNotifyIME() const
+{
+  // If this is already detached from the widget, this doesn't need to notify
+  // anything.
+  if (!mWidget) {
+    return false;
+  }
+
+  // Don't notify IME of anything if it's not good time to do it.
+  if (mSuppressNotifications) {
+    return false;
+  }
+
+  if (!mESM || NS_WARN_IF(!GetPresContext())) {
+    return false;
+  }
+
+  // If it's in reflow, we should wait to finish the reflow.
+  // FYI: This should be called again from Reflow() or ReflowInterruptible().
+  if (IsReflowLocked()) {
+    return false;
+  }
+
+  // If we're in handling an edit action, this method will be called later.
+  bool isInEditAction = false;
+  if (mEditor && NS_SUCCEEDED(mEditor->GetIsInEditAction(&isInEditAction)) &&
+      isInEditAction) {
+    return false;
+  }
+
+  return true;
+}
+
+void
+IMEContentObserver::FlushMergeableNotifications()
+{
+  if (!IsSafeToNotifyIME()) {
+    // So, if this is already called, this should do nothing.
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p IMEContentObserver::FlushMergeableNotifications(), "
+       "FAILED, due to unsafe to notify IME", this));
+    return;
+  }
+
+  // Notifying something may cause nested call of this method.  For example,
+  // when somebody notified one of the notifications may dispatch query content
+  // event. Then, it causes flushing layout which may cause another layout
+  // change notification.
+
+  if (mQueuedSender) {
+    // So, if this is already called, this should do nothing.
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p   IMEContentObserver::FlushMergeableNotifications(), "
+       "FAILED, due to already flushing pending notifications", this));
+    return;
+  }
+
+  if (!NeedsToNotifyIMEOfSomething()) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p   IMEContentObserver::FlushMergeableNotifications(), "
+       "FAILED, due to no pending notifications", this));
+    return;
+  }
+
+  // NOTE: Reset each pending flag because sending notification may cause
+  //       another change.
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::FlushMergeableNotifications(), "
+     "creating IMENotificationSender...", this));
+
+  // If contents in selection range is modified, the selection range still
+  // has removed node from the tree.  In such case, nsContentIterator won't
+  // work well.  Therefore, we shouldn't use AddScriptRunnder() here since
+  // it may kick runnable event immediately after DOM tree is changed but
+  // the selection range isn't modified yet.
+  mQueuedSender = new IMENotificationSender(this);
+  NS_DispatchToCurrentThread(mQueuedSender);
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::FlushMergeableNotifications(), "
+     "finished", this));
+}
+
+void
+IMEContentObserver::TryToFlushPendingNotifications()
+{
+  if (!mQueuedSender || mSendingNotification != NOTIFY_IME_OF_NOTHING) {
+    return;
+  }
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::TryToFlushPendingNotifications(), "
+     "performing queued IMENotificationSender forcibly", this));
+  RefPtr<IMENotificationSender> queuedSender = mQueuedSender;
+  queuedSender->Run();
+}
+
+/******************************************************************************
+ * mozilla::IMEContentObserver::AChangeEvent
+ ******************************************************************************/
+
+bool
+IMEContentObserver::AChangeEvent::CanNotifyIME(
+                                    ChangeEventType aChangeEventType) const
+{
+  if (NS_WARN_IF(!mIMEContentObserver)) {
+    return false;
+  }
+  if (aChangeEventType == eChangeEventType_CompositionEventHandled) {
+    return mIMEContentObserver->mWidget != nullptr;
+  }
+  State state = mIMEContentObserver->GetState();
+  // If it's not initialized, we should do nothing.
+  if (state == eState_NotObserving) {
+    return false;
+  }
+  // If setting focus, just check the state.
+  if (aChangeEventType == eChangeEventType_Focus) {
+    return !NS_WARN_IF(mIMEContentObserver->mIMEHasFocus);
+  }
+  // If we've not notified IME of focus yet, we shouldn't notify anything.
+  if (!mIMEContentObserver->mIMEHasFocus) {
+    return false;
+  }
+
+  // If IME has focus, IMEContentObserver must hold the widget.
+  MOZ_ASSERT(mIMEContentObserver->mWidget);
+
+  return true;
+}
+
+bool
+IMEContentObserver::AChangeEvent::IsSafeToNotifyIME(
+                                    ChangeEventType aChangeEventType) const
+{
+  if (NS_WARN_IF(!nsContentUtils::IsSafeToRunScript())) {
+    return false;
+  }
+  // While we're sending a notification, we shouldn't send another notification
+  // recursively.
+  if (mIMEContentObserver->mSendingNotification != NOTIFY_IME_OF_NOTHING) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p   IMEContentObserver::AChangeEvent::IsSafeToNotifyIME(), "
+       "putting off sending notification due to detecting recursive call, "
+       "mIMEContentObserver={ mSendingNotification=%s }",
+       this, ToChar(mIMEContentObserver->mSendingNotification)));
+    return false;
+  }
+  State state = mIMEContentObserver->GetState();
+  if (aChangeEventType == eChangeEventType_Focus) {
+    if (NS_WARN_IF(state != eState_Initializing && state != eState_Observing)) {
+      return false;
+    }
+  } else if (aChangeEventType == eChangeEventType_CompositionEventHandled) {
+    // It doesn't need to check the observing status.
+  } else if (state != eState_Observing) {
+    return false;
+  }
+  return mIMEContentObserver->IsSafeToNotifyIME();
+}
+
+/******************************************************************************
+ * mozilla::IMEContentObserver::IMENotificationSender
+ ******************************************************************************/
+ 
+NS_IMETHODIMP
+IMEContentObserver::IMENotificationSender::Run()
+{
+  if (NS_WARN_IF(mIsRunning)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Error,
+      ("0x%p IMEContentObserver::IMENotificationSender::Run(), FAILED, "
+       "called recursively", this));
+    return NS_OK;
+  }
+
+  AutoRestore<bool> running(mIsRunning);
+  mIsRunning = true;
+
+  // This instance was already performed forcibly.
+  if (mIMEContentObserver->mQueuedSender != this) {
+    return NS_OK;
+  }
+
+  // NOTE: Reset each pending flag because sending notification may cause
+  //       another change.
+
+  if (mIMEContentObserver->mNeedsToNotifyIMEOfFocusSet) {
+    mIMEContentObserver->mNeedsToNotifyIMEOfFocusSet = false;
+    SendFocusSet();
+    mIMEContentObserver->mQueuedSender = nullptr;
+    // If it's not safe to notify IME of focus, SendFocusSet() sets
+    // mNeedsToNotifyIMEOfFocusSet true again.  For guaranteeing to send the
+    // focus notification later,  we should put a new sender into the queue but
+    // this case must be rare.  Note that if mIMEContentObserver is already
+    // destroyed, mNeedsToNotifyIMEOfFocusSet is never set true again.
+    if (mIMEContentObserver->mNeedsToNotifyIMEOfFocusSet) {
+      MOZ_ASSERT(!mIMEContentObserver->mIMEHasFocus);
+      MOZ_LOG(sIMECOLog, LogLevel::Debug,
+        ("0x%p IMEContentObserver::IMENotificationSender::Run(), "
+         "posting IMENotificationSender to current thread", this));
+      mIMEContentObserver->mQueuedSender =
+        new IMENotificationSender(mIMEContentObserver);
+      NS_DispatchToCurrentThread(mIMEContentObserver->mQueuedSender);
+      return NS_OK;
+    }
+    // This is the first notification to IME. So, we don't need to notify
+    // anymore since IME starts to query content after it gets focus.
+    mIMEContentObserver->ClearPendingNotifications();
+    return NS_OK;
+  }
+
+  if (mIMEContentObserver->mNeedsToNotifyIMEOfTextChange) {
+    mIMEContentObserver->mNeedsToNotifyIMEOfTextChange = false;
+    SendTextChange();
+  }
+
+  // If a text change notification causes another text change again, we should
+  // notify IME of that before sending a selection change notification.
+  if (!mIMEContentObserver->mNeedsToNotifyIMEOfTextChange) {
+    // Be aware, PuppetWidget depends on the order of this. A selection change
+    // notification should not be sent before a text change notification because
+    // PuppetWidget shouldn't query new text content every selection change.
+    if (mIMEContentObserver->mNeedsToNotifyIMEOfSelectionChange) {
+      mIMEContentObserver->mNeedsToNotifyIMEOfSelectionChange = false;
+      SendSelectionChange();
+    }
+  }
+
+  // If a text change notification causes another text change again or a
+  // selection change notification causes either a text change or another
+  // selection change, we should notify IME of those before sending a position
+  // change notification.
+  if (!mIMEContentObserver->mNeedsToNotifyIMEOfTextChange &&
+      !mIMEContentObserver->mNeedsToNotifyIMEOfSelectionChange) {
+    if (mIMEContentObserver->mNeedsToNotifyIMEOfPositionChange) {
+      mIMEContentObserver->mNeedsToNotifyIMEOfPositionChange = false;
+      SendPositionChange();
+    }
+  }
+
+  // Composition event handled notification should be sent after all the
+  // other notifications because this notifies widget of finishing all pending
+  // events are handled completely.
+  if (!mIMEContentObserver->mNeedsToNotifyIMEOfTextChange &&
+      !mIMEContentObserver->mNeedsToNotifyIMEOfSelectionChange &&
+      !mIMEContentObserver->mNeedsToNotifyIMEOfPositionChange) {
+    if (mIMEContentObserver->mNeedsToNotifyIMEOfCompositionEventHandled) {
+      mIMEContentObserver->mNeedsToNotifyIMEOfCompositionEventHandled = false;
+      SendCompositionEventHandled();
+    }
+  }
+
+  mIMEContentObserver->mQueuedSender = nullptr;
+
+  // If notifications caused some new change, we should notify them now.
+  if (mIMEContentObserver->NeedsToNotifyIMEOfSomething()) {
+    if (mIMEContentObserver->GetState() == eState_StoppedObserving) {
+      MOZ_LOG(sIMECOLog, LogLevel::Debug,
+        ("0x%p IMEContentObserver::IMENotificationSender::Run(), "
+         "waiting IMENotificationSender to be reinitialized", this));
+    } else {
+      MOZ_LOG(sIMECOLog, LogLevel::Debug,
+        ("0x%p IMEContentObserver::IMENotificationSender::Run(), "
+         "posting IMENotificationSender to current thread", this));
+      mIMEContentObserver->mQueuedSender =
+        new IMENotificationSender(mIMEContentObserver);
+      NS_DispatchToCurrentThread(mIMEContentObserver->mQueuedSender);
+    }
+  }
+  return NS_OK;
+}
+
+void
+IMEContentObserver::IMENotificationSender::SendFocusSet()
+{
+  if (!CanNotifyIME(eChangeEventType_Focus)) {
+    // If IMEContentObserver has already gone, we don't need to notify IME of
+    // focus.
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p IMEContentObserver::IMENotificationSender::"
+       "SendFocusSet(), FAILED, due to impossible to notify IME of focus",
+       this));
+    mIMEContentObserver->ClearPendingNotifications();
+    return;
+  }
+
+  if (!IsSafeToNotifyIME(eChangeEventType_Focus)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p   IMEContentObserver::IMENotificationSender::"
+       "SendFocusSet(), retrying to send NOTIFY_IME_OF_FOCUS...", this));
+    mIMEContentObserver->PostFocusSetNotification();
+    return;
+  }
+
+  mIMEContentObserver->mIMEHasFocus = true;
+  // Initialize selection cache with the first selection data.
+  mIMEContentObserver->UpdateSelectionCache();
+
+  MOZ_LOG(sIMECOLog, LogLevel::Info,
+    ("0x%p IMEContentObserver::IMENotificationSender::"
+     "SendFocusSet(), sending NOTIFY_IME_OF_FOCUS...", this));
+
+  MOZ_RELEASE_ASSERT(mIMEContentObserver->mSendingNotification ==
+                       NOTIFY_IME_OF_NOTHING);
+  mIMEContentObserver->mSendingNotification = NOTIFY_IME_OF_FOCUS;
+  IMEStateManager::NotifyIME(IMENotification(NOTIFY_IME_OF_FOCUS),
+                             mIMEContentObserver->mWidget);
+  mIMEContentObserver->mSendingNotification = NOTIFY_IME_OF_NOTHING;
+
+  // nsIMEUpdatePreference referred by ObserveEditableNode() may be different
+  // before or after widget receives NOTIFY_IME_OF_FOCUS.  Therefore, we need
+  // to guarantee to call ObserveEditableNode() after sending
+  // NOTIFY_IME_OF_FOCUS.
+  mIMEContentObserver->OnIMEReceivedFocus();
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::IMENotificationSender::"
+     "SendFocusSet(), sent NOTIFY_IME_OF_FOCUS", this));
+}
+
+void
+IMEContentObserver::IMENotificationSender::SendSelectionChange()
+{
+  if (!CanNotifyIME(eChangeEventType_Selection)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p IMEContentObserver::IMENotificationSender::"
+       "SendSelectionChange(), FAILED, due to impossible to notify IME of "
+       "selection change", this));
+    return;
+  }
+
+  if (!IsSafeToNotifyIME(eChangeEventType_Selection)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p   IMEContentObserver::IMENotificationSender::"
+       "SendSelectionChange(), retrying to send "
+       "NOTIFY_IME_OF_SELECTION_CHANGE...", this));
+    mIMEContentObserver->PostSelectionChangeNotification();
+    return;
+  }
+
+  SelectionChangeData lastSelChangeData = mIMEContentObserver->mSelectionData;
+  if (NS_WARN_IF(!mIMEContentObserver->UpdateSelectionCache())) {
+    MOZ_LOG(sIMECOLog, LogLevel::Error,
+      ("0x%p IMEContentObserver::IMENotificationSender::"
+       "SendSelectionChange(), FAILED, due to UpdateSelectionCache() failure",
+       this));
+    return;
+  }
+
+  // The state may be changed since querying content causes flushing layout.
+  if (!CanNotifyIME(eChangeEventType_Selection)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p IMEContentObserver::IMENotificationSender::"
+       "SendSelectionChange(), FAILED, due to flushing layout having changed "
+       "something", this));
+    return;
+  }
+
+  // If the selection isn't changed actually, we shouldn't notify IME of
+  // selection change.
+  SelectionChangeData& newSelChangeData = mIMEContentObserver->mSelectionData;
+  if (lastSelChangeData.IsValid() &&
+      lastSelChangeData.mOffset == newSelChangeData.mOffset &&
+      lastSelChangeData.String() == newSelChangeData.String() &&
+      lastSelChangeData.GetWritingMode() == newSelChangeData.GetWritingMode() &&
+      lastSelChangeData.mReversed == newSelChangeData.mReversed) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p IMEContentObserver::IMENotificationSender::"
+       "SendSelectionChange(), not notifying IME of "
+       "NOTIFY_IME_OF_SELECTION_CHANGE due to not changed actually", this));
+    return;
+  }
+
+  MOZ_LOG(sIMECOLog, LogLevel::Info,
+    ("0x%p IMEContentObserver::IMENotificationSender::"
+     "SendSelectionChange(), sending NOTIFY_IME_OF_SELECTION_CHANGE... "
+     "newSelChangeData=%s",
+     this, SelectionChangeDataToString(newSelChangeData).get()));
+
+  IMENotification notification(NOTIFY_IME_OF_SELECTION_CHANGE);
+  notification.SetData(mIMEContentObserver->mSelectionData);
+
+  MOZ_RELEASE_ASSERT(mIMEContentObserver->mSendingNotification ==
+                       NOTIFY_IME_OF_NOTHING);
+  mIMEContentObserver->mSendingNotification = NOTIFY_IME_OF_SELECTION_CHANGE;
+  IMEStateManager::NotifyIME(notification, mIMEContentObserver->mWidget);
+  mIMEContentObserver->mSendingNotification = NOTIFY_IME_OF_NOTHING;
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::IMENotificationSender::"
+     "SendSelectionChange(), sent NOTIFY_IME_OF_SELECTION_CHANGE", this));
+}
+
+void
+IMEContentObserver::IMENotificationSender::SendTextChange()
+{
+  if (!CanNotifyIME(eChangeEventType_Text)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p IMEContentObserver::IMENotificationSender::"
+       "SendTextChange(), FAILED, due to impossible to notify IME of text "
+       "change", this));
+    return;
+  }
+
+  if (!IsSafeToNotifyIME(eChangeEventType_Text)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p   IMEContentObserver::IMENotificationSender::"
+       "SendTextChange(), retrying to send NOTIFY_IME_OF_TEXT_CHANGE...",
+       this));
+    mIMEContentObserver->PostTextChangeNotification();
+    return;
+  }
+
+  MOZ_LOG(sIMECOLog, LogLevel::Info,
+    ("0x%p IMEContentObserver::IMENotificationSender::"
+     "SendTextChange(), sending NOTIFY_IME_OF_TEXT_CHANGE... "
+     "mIMEContentObserver={ mTextChangeData=%s }",
+     this, TextChangeDataToString(mIMEContentObserver->mTextChangeData).get()));
+
+  IMENotification notification(NOTIFY_IME_OF_TEXT_CHANGE);
+  notification.SetData(mIMEContentObserver->mTextChangeData);
+  mIMEContentObserver->mTextChangeData.Clear();
+
+  MOZ_RELEASE_ASSERT(mIMEContentObserver->mSendingNotification ==
+                       NOTIFY_IME_OF_NOTHING);
+  mIMEContentObserver->mSendingNotification = NOTIFY_IME_OF_TEXT_CHANGE;
+  IMEStateManager::NotifyIME(notification, mIMEContentObserver->mWidget);
+  mIMEContentObserver->mSendingNotification = NOTIFY_IME_OF_NOTHING;
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::IMENotificationSender::"
+     "SendTextChange(), sent NOTIFY_IME_OF_TEXT_CHANGE", this));
+}
+
+void
+IMEContentObserver::IMENotificationSender::SendPositionChange()
+{
+  if (!CanNotifyIME(eChangeEventType_Position)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p IMEContentObserver::IMENotificationSender::"
+       "SendPositionChange(), FAILED, due to impossible to notify IME of "
+       "position change", this));
+    return;
+  }
+
+  if (!IsSafeToNotifyIME(eChangeEventType_Position)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p   IMEContentObserver::IMENotificationSender::"
+       "SendPositionChange(), retrying to send "
+       "NOTIFY_IME_OF_POSITION_CHANGE...", this));
+    mIMEContentObserver->PostPositionChangeNotification();
+    return;
+  }
+
+  MOZ_LOG(sIMECOLog, LogLevel::Info,
+    ("0x%p IMEContentObserver::IMENotificationSender::"
+     "SendPositionChange(), sending NOTIFY_IME_OF_POSITION_CHANGE...", this));
+
+  MOZ_RELEASE_ASSERT(mIMEContentObserver->mSendingNotification ==
+                       NOTIFY_IME_OF_NOTHING);
+  mIMEContentObserver->mSendingNotification = NOTIFY_IME_OF_POSITION_CHANGE;
+  IMEStateManager::NotifyIME(IMENotification(NOTIFY_IME_OF_POSITION_CHANGE),
+                             mIMEContentObserver->mWidget);
+  mIMEContentObserver->mSendingNotification = NOTIFY_IME_OF_NOTHING;
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::IMENotificationSender::"
+     "SendPositionChange(), sent NOTIFY_IME_OF_POSITION_CHANGE", this));
+}
+
+void
+IMEContentObserver::IMENotificationSender::SendCompositionEventHandled()
+{
+  if (!CanNotifyIME(eChangeEventType_CompositionEventHandled)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p IMEContentObserver::IMENotificationSender::"
+       "SendCompositionEventHandled(), FAILED, due to impossible to notify "
+       "IME of composition event handled", this));
+    return;
+  }
+
+  if (!IsSafeToNotifyIME(eChangeEventType_CompositionEventHandled)) {
+    MOZ_LOG(sIMECOLog, LogLevel::Debug,
+      ("0x%p   IMEContentObserver::IMENotificationSender::"
+       "SendCompositionEventHandled(), retrying to send "
+       "NOTIFY_IME_OF_POSITION_CHANGE...", this));
+    mIMEContentObserver->PostCompositionEventHandledNotification();
+    return;
+  }
+
+  MOZ_LOG(sIMECOLog, LogLevel::Info,
+    ("0x%p IMEContentObserver::IMENotificationSender::"
+     "SendCompositionEventHandled(), sending "
+     "NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED...", this));
+
+  MOZ_RELEASE_ASSERT(mIMEContentObserver->mSendingNotification ==
+                       NOTIFY_IME_OF_NOTHING);
+  mIMEContentObserver->mSendingNotification =
+                         NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED;
+  IMEStateManager::NotifyIME(
+                     IMENotification(NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED),
+                     mIMEContentObserver->mWidget);
+  mIMEContentObserver->mSendingNotification = NOTIFY_IME_OF_NOTHING;
+
+  MOZ_LOG(sIMECOLog, LogLevel::Debug,
+    ("0x%p IMEContentObserver::IMENotificationSender::"
+     "SendCompositionEventHandled(), sent "
+     "NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED", this));
+}
+
+} // namespace mozilla