Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

15 files changed, 3395 insertions, 0 deletions

diff --git a/editor/txmgr/TransactionItem.cpp b/editor/txmgr/TransactionItem.cpp
new file mode 100644
index 0000000000..26d114dfc9
--- /dev/null
+++ b/editor/txmgr/TransactionItem.cpp
@@ -0,0 +1,257 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "TransactionItem.h"
+
+#include "mozilla/mozalloc.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/IntegerRange.h"
+#include "mozilla/OwningNonNull.h"
+#include "mozilla/TransactionManager.h"
+#include "mozilla/TransactionStack.h"
+#include "nsCOMPtr.h"
+#include "nsDebug.h"
+#include "nsError.h"
+#include "nsISupportsImpl.h"
+#include "nsITransaction.h"
+
+namespace mozilla {
+
+TransactionItem::TransactionItem(nsITransaction* aTransaction)
+    : mTransaction(aTransaction), mUndoStack(0), mRedoStack(0) {}
+
+TransactionItem::~TransactionItem() {
+  delete mRedoStack;
+  delete mUndoStack;
+}
+
+void TransactionItem::CleanUp() {
+  mData.Clear();
+  mTransaction = nullptr;
+  if (mRedoStack) {
+    mRedoStack->DoUnlink();
+  }
+  if (mUndoStack) {
+    mUndoStack->DoUnlink();
+  }
+}
+
+NS_IMPL_CYCLE_COLLECTING_NATIVE_ADDREF(TransactionItem)
+NS_IMPL_CYCLE_COLLECTING_NATIVE_RELEASE_WITH_LAST_RELEASE(TransactionItem,
+                                                          CleanUp())
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(TransactionItem)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(TransactionItem)
+  tmp->CleanUp();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(TransactionItem)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mData)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mTransaction)
+  if (tmp->mRedoStack) {
+    tmp->mRedoStack->DoTraverse(cb);
+  }
+  if (tmp->mUndoStack) {
+    tmp->mUndoStack->DoTraverse(cb);
+  }
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+nsresult TransactionItem::AddChild(TransactionItem& aTransactionItem) {
+  if (!mUndoStack) {
+    mUndoStack = new TransactionStack(TransactionStack::FOR_UNDO);
+  }
+
+  mUndoStack->Push(&aTransactionItem);
+  return NS_OK;
+}
+
+already_AddRefed<nsITransaction> TransactionItem::GetTransaction() {
+  return do_AddRef(mTransaction);
+}
+
+nsresult TransactionItem::DoTransaction() {
+  if (!mTransaction) {
+    return NS_OK;
+  }
+  OwningNonNull<nsITransaction> transaction = *mTransaction;
+  nsresult rv = transaction->DoTransaction();
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                       "nsITransaction::DoTransaction() failed");
+  return rv;
+}
+
+nsresult TransactionItem::UndoTransaction(
+    TransactionManager* aTransactionManager) {
+  nsresult rv = UndoChildren(aTransactionManager);
+  if (NS_FAILED(rv)) {
+    NS_WARNING("TransactionItem::UndoChildren() failed");
+    DebugOnly<nsresult> rvIgnored = RecoverFromUndoError(aTransactionManager);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rvIgnored),
+                         "TransactionItem::RecoverFromUndoError() failed");
+    return rv;
+  }
+
+  if (!mTransaction) {
+    return NS_OK;
+  }
+
+  OwningNonNull<nsITransaction> transaction = *mTransaction;
+  rv = transaction->UndoTransaction();
+  if (NS_SUCCEEDED(rv)) {
+    return NS_OK;
+  }
+
+  NS_WARNING("TransactionItem::UndoTransaction() failed");
+  DebugOnly<nsresult> rvIgnored = RecoverFromUndoError(aTransactionManager);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rvIgnored),
+                       "TransactionItem::RecoverFromUndoError() failed");
+  return rv;
+}
+
+nsresult TransactionItem::UndoChildren(
+    TransactionManager* aTransactionManager) {
+  if (!mUndoStack) {
+    return NS_OK;
+  }
+
+  if (!mRedoStack) {
+    mRedoStack = new TransactionStack(TransactionStack::FOR_REDO);
+  }
+
+  const size_t undoStackSize = mUndoStack->GetSize();
+
+  nsresult rv = NS_OK;
+  for ([[maybe_unused]] const size_t undoneCount :
+       IntegerRange(undoStackSize)) {
+    RefPtr<TransactionItem> transactionItem = mUndoStack->Peek();
+    if (!transactionItem) {
+      return NS_ERROR_FAILURE;
+    }
+
+    nsCOMPtr<nsITransaction> transaction = transactionItem->GetTransaction();
+    rv = transactionItem->UndoTransaction(aTransactionManager);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                         "TransactionItem::UndoTransaction() failed");
+    if (NS_SUCCEEDED(rv)) {
+      transactionItem = mUndoStack->Pop();
+      mRedoStack->Push(transactionItem.forget());
+    }
+
+    if (transaction) {
+      aTransactionManager->DidUndoNotify(*transaction, rv);
+    }
+  }
+  // NS_OK if there is no Undo items or all methods work fine, otherwise,
+  // the result of the last item's UndoTransaction().
+  return rv;
+}
+
+nsresult TransactionItem::RedoTransaction(
+    TransactionManager* aTransactionManager) {
+  nsCOMPtr<nsITransaction> transaction(mTransaction);
+  if (transaction) {
+    nsresult rv = transaction->RedoTransaction();
+    if (NS_FAILED(rv)) {
+      NS_WARNING("nsITransaction::RedoTransaction() failed");
+      return rv;
+    }
+  }
+
+  nsresult rv = RedoChildren(aTransactionManager);
+  if (NS_SUCCEEDED(rv)) {
+    return NS_OK;
+  }
+
+  NS_WARNING("TransactionItem::RedoChildren() failed");
+  DebugOnly<nsresult> rvIgnored = RecoverFromRedoError(aTransactionManager);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rvIgnored),
+                       "TransactionItem::RecoverFromRedoError() failed");
+  return rv;
+}
+
+nsresult TransactionItem::RedoChildren(
+    TransactionManager* aTransactionManager) {
+  if (!mRedoStack) {
+    return NS_OK;
+  }
+
+  /* Redo all of the transaction items children! */
+  const size_t redoStackSize = mRedoStack->GetSize();
+
+  nsresult rv = NS_OK;
+  for ([[maybe_unused]] const size_t redoneCount :
+       IntegerRange(redoStackSize)) {
+    RefPtr<TransactionItem> transactionItem = mRedoStack->Peek();
+    if (NS_WARN_IF(!transactionItem)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    nsCOMPtr<nsITransaction> transaction = transactionItem->GetTransaction();
+    rv = transactionItem->RedoTransaction(aTransactionManager);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                         "TransactionItem::RedoTransaction() failed");
+    if (NS_SUCCEEDED(rv)) {
+      transactionItem = mRedoStack->Pop();
+      mUndoStack->Push(transactionItem.forget());
+    }
+
+    // XXX Shouldn't this DidRedoNotify()? (bug 1311626)
+    if (transaction) {
+      aTransactionManager->DidUndoNotify(*transaction, rv);
+    }
+  }
+  // NS_OK if there is no Redo items or all methods work fine, otherwise,
+  // the result of the last item's RedoTransaction().
+  return rv;
+}
+
+size_t TransactionItem::NumberOfUndoItems() const {
+  NS_WARNING_ASSERTION(!mUndoStack || mUndoStack->GetSize() > 0,
+                       "UndoStack cannot have no children");
+  return mUndoStack ? mUndoStack->GetSize() : 0;
+}
+
+size_t TransactionItem::NumberOfRedoItems() const {
+  NS_WARNING_ASSERTION(!mRedoStack || mRedoStack->GetSize() > 0,
+                       "UndoStack cannot have no children");
+  return mRedoStack ? mRedoStack->GetSize() : 0;
+}
+
+nsresult TransactionItem::RecoverFromUndoError(
+    TransactionManager* aTransactionManager) {
+  // If this method gets called, we never got to the point where we
+  // successfully called UndoTransaction() for the transaction item itself.
+  // Just redo any children that successfully called undo!
+  nsresult rv = RedoChildren(aTransactionManager);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                       "TransactionItem::RedoChildren() failed");
+  return rv;
+}
+
+nsresult TransactionItem::RecoverFromRedoError(
+    TransactionManager* aTransactionManager) {
+  // If this method gets called, we already successfully called
+  // RedoTransaction() for the transaction item itself. Undo all
+  // the children that successfully called RedoTransaction(),
+  // then undo the transaction item itself.
+  nsresult rv = UndoChildren(aTransactionManager);
+  if (NS_FAILED(rv)) {
+    NS_WARNING("TransactionItem::UndoChildren() failed");
+    return rv;
+  }
+
+  if (!mTransaction) {
+    return NS_OK;
+  }
+
+  OwningNonNull<nsITransaction> transaction = *mTransaction;
+  rv = transaction->UndoTransaction();
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                       "nsITransaction::UndoTransaction() failed");
+  return rv;
+}
+
+}  // namespace mozilla
diff --git a/editor/txmgr/TransactionItem.h b/editor/txmgr/TransactionItem.h
new file mode 100644
index 0000000000..6a8142a1fa
--- /dev/null
+++ b/editor/txmgr/TransactionItem.h
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#ifndef TransactionItem_h
+#define TransactionItem_h
+
+#include "nsCOMPtr.h"
+#include "nsCOMArray.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsISupportsImpl.h"
+#include "nscore.h"
+
+class nsITransaction;
+
+namespace mozilla {
+
+class TransactionManager;
+class TransactionStack;
+
+class TransactionItem final {
+ public:
+  explicit TransactionItem(nsITransaction* aTransaction);
+  NS_METHOD_(MozExternalRefCountType) AddRef();
+  NS_METHOD_(MozExternalRefCountType) Release();
+
+  NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(TransactionItem)
+
+  nsresult AddChild(TransactionItem& aTransactionItem);
+  already_AddRefed<nsITransaction> GetTransaction();
+  size_t NumberOfChildren() const {
+    return NumberOfUndoItems() + NumberOfRedoItems();
+  }
+  nsresult GetChild(size_t aIndex, TransactionItem** aChild);
+
+  MOZ_CAN_RUN_SCRIPT nsresult DoTransaction();
+  MOZ_CAN_RUN_SCRIPT nsresult
+  UndoTransaction(TransactionManager* aTransactionManager);
+  MOZ_CAN_RUN_SCRIPT nsresult
+  RedoTransaction(TransactionManager* aTransactionManager);
+
+  nsCOMArray<nsISupports>& GetData() { return mData; }
+
+ private:
+  MOZ_CAN_RUN_SCRIPT nsresult
+  UndoChildren(TransactionManager* aTransactionManager);
+  MOZ_CAN_RUN_SCRIPT nsresult
+  RedoChildren(TransactionManager* aTransactionManager);
+
+  MOZ_CAN_RUN_SCRIPT nsresult
+  RecoverFromUndoError(TransactionManager* aTransactionManager);
+  MOZ_CAN_RUN_SCRIPT nsresult
+  RecoverFromRedoError(TransactionManager* aTransactionManager);
+
+  size_t NumberOfUndoItems() const;
+  size_t NumberOfRedoItems() const;
+
+  void CleanUp();
+
+  ~TransactionItem();
+
+  nsCycleCollectingAutoRefCnt mRefCnt;
+  NS_DECL_OWNINGTHREAD
+
+  nsCOMArray<nsISupports> mData;
+  nsCOMPtr<nsITransaction> mTransaction;
+  TransactionStack* mUndoStack;
+  TransactionStack* mRedoStack;
+};
+
+}  // namespace mozilla
+
+#endif  // #ifndef TransactionItem_h
diff --git a/editor/txmgr/TransactionManager.cpp b/editor/txmgr/TransactionManager.cpp
new file mode 100644
index 0000000000..ad4d641d56
--- /dev/null
+++ b/editor/txmgr/TransactionManager.cpp
@@ -0,0 +1,509 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/TransactionManager.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/HTMLEditor.h"
+#include "mozilla/mozalloc.h"
+#include "mozilla/TransactionStack.h"
+#include "nsCOMPtr.h"
+#include "nsDebug.h"
+#include "nsError.h"
+#include "nsISupports.h"
+#include "nsISupportsUtils.h"
+#include "nsITransaction.h"
+#include "nsIWeakReference.h"
+#include "TransactionItem.h"
+
+namespace mozilla {
+
+TransactionManager::TransactionManager(int32_t aMaxTransactionCount)
+    : mMaxTransactionCount(aMaxTransactionCount),
+      mDoStack(TransactionStack::FOR_UNDO),
+      mUndoStack(TransactionStack::FOR_UNDO),
+      mRedoStack(TransactionStack::FOR_REDO) {}
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(TransactionManager)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(TransactionManager)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mHTMLEditor)
+  tmp->mDoStack.DoUnlink();
+  tmp->mUndoStack.DoUnlink();
+  tmp->mRedoStack.DoUnlink();
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_WEAK_REFERENCE
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(TransactionManager)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mHTMLEditor)
+  tmp->mDoStack.DoTraverse(cb);
+  tmp->mUndoStack.DoTraverse(cb);
+  tmp->mRedoStack.DoTraverse(cb);
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TransactionManager)
+  NS_INTERFACE_MAP_ENTRY(nsITransactionManager)
+  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsITransactionManager)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(TransactionManager)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(TransactionManager)
+
+void TransactionManager::Attach(HTMLEditor& aHTMLEditor) {
+  mHTMLEditor = &aHTMLEditor;
+}
+
+void TransactionManager::Detach(const HTMLEditor& aHTMLEditor) {
+  MOZ_DIAGNOSTIC_ASSERT_IF(mHTMLEditor, &aHTMLEditor == mHTMLEditor);
+  if (mHTMLEditor == &aHTMLEditor) {
+    mHTMLEditor = nullptr;
+  }
+}
+
+MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP
+TransactionManager::DoTransaction(nsITransaction* aTransaction) {
+  if (NS_WARN_IF(!aTransaction)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  OwningNonNull<nsITransaction> transaction = *aTransaction;
+
+  nsresult rv = BeginTransaction(transaction, nullptr);
+  if (NS_FAILED(rv)) {
+    NS_WARNING("TransactionManager::BeginTransaction() failed");
+    DidDoNotify(transaction, rv);
+    return rv;
+  }
+
+  rv = EndTransaction(false);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                       "TransactionManager::EndTransaction() failed");
+
+  DidDoNotify(transaction, rv);
+  return rv;
+}
+
+MOZ_CAN_RUN_SCRIPT NS_IMETHODIMP TransactionManager::UndoTransaction() {
+  return Undo();
+}
+
+nsresult TransactionManager::Undo() {
+  // It's possible to be called Undo() again while the transaction manager is
+  // executing a transaction's DoTransaction() method.  If this happens,
+  // the Undo() request is ignored, and we return NS_ERROR_FAILURE.  This
+  // may occur if a mutation event listener calls document.execCommand("undo").
+  if (NS_WARN_IF(!mDoStack.IsEmpty())) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Peek at the top of the undo stack. Don't remove the transaction
+  // until it has successfully completed.
+  RefPtr<TransactionItem> transactionItem = mUndoStack.Peek();
+  if (!transactionItem) {
+    // Bail if there's nothing on the stack.
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsITransaction> transaction = transactionItem->GetTransaction();
+  nsresult rv = transactionItem->UndoTransaction(this);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                       "TransactionItem::UndoTransaction() failed");
+  if (NS_SUCCEEDED(rv)) {
+    transactionItem = mUndoStack.Pop();
+    mRedoStack.Push(transactionItem.forget());
+  }
+
+  if (transaction) {
+    DidUndoNotify(*transaction, rv);
+  }
+  return rv;
+}
+
+MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP
+TransactionManager::RedoTransaction() {
+  return Redo();
+}
+
+nsresult TransactionManager::Redo() {
+  // It's possible to be called Redo() again while the transaction manager is
+  // executing a transaction's DoTransaction() method.  If this happens,
+  // the Redo() request is ignored, and we return NS_ERROR_FAILURE.  This
+  // may occur if a mutation event listener calls document.execCommand("redo").
+  if (NS_WARN_IF(!mDoStack.IsEmpty())) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Peek at the top of the redo stack. Don't remove the transaction
+  // until it has successfully completed.
+  RefPtr<TransactionItem> transactionItem = mRedoStack.Peek();
+  if (!transactionItem) {
+    // Bail if there's nothing on the stack.
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsITransaction> transaction = transactionItem->GetTransaction();
+  nsresult rv = transactionItem->RedoTransaction(this);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                       "TransactionItem::RedoTransaction() failed");
+  if (NS_SUCCEEDED(rv)) {
+    transactionItem = mRedoStack.Pop();
+    mUndoStack.Push(transactionItem.forget());
+  }
+
+  if (transaction) {
+    DidRedoNotify(*transaction, rv);
+  }
+  return rv;
+}
+
+NS_IMETHODIMP TransactionManager::Clear() {
+  return NS_WARN_IF(!ClearUndoRedo()) ? NS_ERROR_FAILURE : NS_OK;
+}
+
+NS_IMETHODIMP TransactionManager::BeginBatch(nsISupports* aData) {
+  nsresult rv = BeginBatchInternal(aData);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                       "TransactionManager::BeginBatchInternal() failed");
+  return rv;
+}
+
+nsresult TransactionManager::BeginBatchInternal(nsISupports* aData) {
+  // We can batch independent transactions together by simply pushing
+  // a dummy transaction item on the do stack. This dummy transaction item
+  // will be popped off the do stack, and then pushed on the undo stack
+  // in EndBatch().
+  nsresult rv = BeginTransaction(nullptr, aData);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                       "TransactionManager::BeginTransaction() failed");
+  return rv;
+}
+
+NS_IMETHODIMP TransactionManager::EndBatch(bool aAllowEmpty) {
+  nsresult rv = EndBatchInternal(aAllowEmpty);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                       "TransactionManager::EndBatchInternal() failed");
+  return rv;
+}
+
+nsresult TransactionManager::EndBatchInternal(bool aAllowEmpty) {
+  // XXX: Need to add some mechanism to detect the case where the transaction
+  //      at the top of the do stack isn't the dummy transaction, so we can
+  //      throw an error!! This can happen if someone calls EndBatch() within
+  //      the DoTransaction() method of a transaction.
+  //
+  //      For now, we can detect this case by checking the value of the
+  //      dummy transaction's mTransaction field. If it is our dummy
+  //      transaction, it should be nullptr. This may not be true in the
+  //      future when we allow users to execute a transaction when beginning
+  //      a batch!!!!
+  RefPtr<TransactionItem> transactionItem = mDoStack.Peek();
+  if (NS_WARN_IF(!transactionItem)) {
+    return NS_ERROR_FAILURE;
+  }
+  nsCOMPtr<nsITransaction> transaction = transactionItem->GetTransaction();
+  if (NS_WARN_IF(transaction)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsresult rv = EndTransaction(aAllowEmpty);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                       "TransactionManager::EndTransaction() failed");
+  return rv;
+}
+
+NS_IMETHODIMP TransactionManager::GetNumberOfUndoItems(int32_t* aNumItems) {
+  *aNumItems = static_cast<int32_t>(NumberOfUndoItems());
+  MOZ_ASSERT(*aNumItems >= 0);
+  return NS_OK;
+}
+
+NS_IMETHODIMP TransactionManager::GetNumberOfRedoItems(int32_t* aNumItems) {
+  *aNumItems = static_cast<int32_t>(NumberOfRedoItems());
+  MOZ_ASSERT(*aNumItems >= 0);
+  return NS_OK;
+}
+
+NS_IMETHODIMP TransactionManager::GetMaxTransactionCount(int32_t* aMaxCount) {
+  if (NS_WARN_IF(!aMaxCount)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aMaxCount = mMaxTransactionCount;
+  return NS_OK;
+}
+
+NS_IMETHODIMP TransactionManager::SetMaxTransactionCount(int32_t aMaxCount) {
+  return NS_WARN_IF(!EnableUndoRedo(aMaxCount)) ? NS_ERROR_FAILURE : NS_OK;
+}
+
+bool TransactionManager::EnableUndoRedo(int32_t aMaxTransactionCount) {
+  // It is illegal to call EnableUndoRedo() while the transaction manager is
+  // executing a transaction's DoTransaction() method because the undo and redo
+  // stacks might get pruned.  If this happens, the EnableUndoRedo() request is
+  // ignored, and we return false.
+  if (NS_WARN_IF(!mDoStack.IsEmpty())) {
+    return false;
+  }
+
+  // If aMaxTransactionCount is 0, it means to disable undo/redo.
+  if (!aMaxTransactionCount) {
+    mUndoStack.Clear();
+    mRedoStack.Clear();
+    mMaxTransactionCount = 0;
+    return true;
+  }
+
+  // If aMaxTransactionCount is less than zero, the user wants unlimited
+  // levels of undo! No need to prune the undo or redo stacks.
+  if (aMaxTransactionCount < 0) {
+    mMaxTransactionCount = -1;
+    return true;
+  }
+
+  // If new max transaction count is greater than or equal to current max
+  // transaction count, we don't need to remove any transactions.
+  if (mMaxTransactionCount >= 0 &&
+      mMaxTransactionCount <= aMaxTransactionCount) {
+    mMaxTransactionCount = aMaxTransactionCount;
+    return true;
+  }
+
+  // If aMaxTransactionCount is greater than the number of transactions that
+  // currently exist on the undo and redo stack, there is no need to prune the
+  // undo or redo stacks.
+  size_t numUndoItems = NumberOfUndoItems();
+  size_t numRedoItems = NumberOfRedoItems();
+  size_t total = numUndoItems + numRedoItems;
+  size_t newMaxTransactionCount = static_cast<size_t>(aMaxTransactionCount);
+  if (newMaxTransactionCount > total) {
+    mMaxTransactionCount = aMaxTransactionCount;
+    return true;
+  }
+
+  // Try getting rid of some transactions on the undo stack! Start at
+  // the bottom of the stack and pop towards the top.
+  for (; numUndoItems && (numRedoItems + numUndoItems) > newMaxTransactionCount;
+       numUndoItems--) {
+    RefPtr<TransactionItem> transactionItem = mUndoStack.PopBottom();
+    MOZ_ASSERT(transactionItem);
+  }
+
+  // If necessary, get rid of some transactions on the redo stack! Start at
+  // the bottom of the stack and pop towards the top.
+  for (; numRedoItems && (numRedoItems + numUndoItems) > newMaxTransactionCount;
+       numRedoItems--) {
+    RefPtr<TransactionItem> transactionItem = mRedoStack.PopBottom();
+    MOZ_ASSERT(transactionItem);
+  }
+
+  mMaxTransactionCount = aMaxTransactionCount;
+  return true;
+}
+
+NS_IMETHODIMP TransactionManager::PeekUndoStack(nsITransaction** aTransaction) {
+  MOZ_ASSERT(aTransaction);
+  *aTransaction = PeekUndoStack().take();
+  return NS_OK;
+}
+
+already_AddRefed<nsITransaction> TransactionManager::PeekUndoStack() {
+  RefPtr<TransactionItem> transactionItem = mUndoStack.Peek();
+  if (!transactionItem) {
+    return nullptr;
+  }
+  return transactionItem->GetTransaction();
+}
+
+NS_IMETHODIMP TransactionManager::PeekRedoStack(nsITransaction** aTransaction) {
+  MOZ_ASSERT(aTransaction);
+  *aTransaction = PeekRedoStack().take();
+  return NS_OK;
+}
+
+already_AddRefed<nsITransaction> TransactionManager::PeekRedoStack() {
+  RefPtr<TransactionItem> transactionItem = mRedoStack.Peek();
+  if (!transactionItem) {
+    return nullptr;
+  }
+  return transactionItem->GetTransaction();
+}
+
+nsresult TransactionManager::BatchTopUndo() {
+  if (mUndoStack.GetSize() < 2) {
+    // Not enough transactions to merge into one batch.
+    return NS_OK;
+  }
+
+  RefPtr<TransactionItem> lastUndo = mUndoStack.Pop();
+  MOZ_ASSERT(lastUndo, "There should be at least two transactions.");
+
+  RefPtr<TransactionItem> previousUndo = mUndoStack.Peek();
+  MOZ_ASSERT(previousUndo, "There should be at least two transactions.");
+
+  nsresult rv = previousUndo->AddChild(*lastUndo);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "TransactionItem::AddChild() failed");
+
+  // Transfer data from the transactions that is going to be
+  // merged to the transaction that it is being merged with.
+  nsCOMArray<nsISupports>& lastData = lastUndo->GetData();
+  nsCOMArray<nsISupports>& previousData = previousUndo->GetData();
+  if (!previousData.AppendObjects(lastData)) {
+    NS_WARNING("nsISupports::AppendObjects() failed");
+    return NS_ERROR_FAILURE;
+  }
+  lastData.Clear();
+  return rv;
+}
+
+nsresult TransactionManager::RemoveTopUndo() {
+  if (mUndoStack.IsEmpty()) {
+    return NS_OK;
+  }
+
+  RefPtr<TransactionItem> lastUndo = mUndoStack.Pop();
+  return NS_OK;
+}
+
+NS_IMETHODIMP TransactionManager::ClearUndoStack() {
+  if (NS_WARN_IF(!mDoStack.IsEmpty())) {
+    return NS_ERROR_FAILURE;
+  }
+  mUndoStack.Clear();
+  return NS_OK;
+}
+
+NS_IMETHODIMP TransactionManager::ClearRedoStack() {
+  if (NS_WARN_IF(!mDoStack.IsEmpty())) {
+    return NS_ERROR_FAILURE;
+  }
+  mRedoStack.Clear();
+  return NS_OK;
+}
+
+void TransactionManager::DidDoNotify(nsITransaction& aTransaction,
+                                     nsresult aDoResult) {
+  if (mHTMLEditor) {
+    RefPtr<HTMLEditor> htmlEditor(mHTMLEditor);
+    htmlEditor->DidDoTransaction(*this, aTransaction, aDoResult);
+  }
+}
+
+void TransactionManager::DidUndoNotify(nsITransaction& aTransaction,
+                                       nsresult aUndoResult) {
+  if (mHTMLEditor) {
+    RefPtr<HTMLEditor> htmlEditor(mHTMLEditor);
+    htmlEditor->DidUndoTransaction(*this, aTransaction, aUndoResult);
+  }
+}
+
+void TransactionManager::DidRedoNotify(nsITransaction& aTransaction,
+                                       nsresult aRedoResult) {
+  if (mHTMLEditor) {
+    RefPtr<HTMLEditor> htmlEditor(mHTMLEditor);
+    htmlEditor->DidRedoTransaction(*this, aTransaction, aRedoResult);
+  }
+}
+
+nsresult TransactionManager::BeginTransaction(nsITransaction* aTransaction,
+                                              nsISupports* aData) {
+  // XXX: POSSIBLE OPTIMIZATION
+  //      We could use a factory that pre-allocates/recycles transaction items.
+  RefPtr<TransactionItem> transactionItem = new TransactionItem(aTransaction);
+
+  if (aData) {
+    nsCOMArray<nsISupports>& data = transactionItem->GetData();
+    data.AppendObject(aData);
+  }
+
+  mDoStack.Push(transactionItem);
+
+  nsresult rv = transactionItem->DoTransaction();
+  if (NS_FAILED(rv)) {
+    NS_WARNING("TransactionItem::DoTransaction() failed");
+    transactionItem = mDoStack.Pop();
+  }
+  return rv;
+}
+
+nsresult TransactionManager::EndTransaction(bool aAllowEmpty) {
+  RefPtr<TransactionItem> transactionItem = mDoStack.Pop();
+  if (NS_WARN_IF(!transactionItem)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsITransaction> transaction = transactionItem->GetTransaction();
+  if (!transaction && !aAllowEmpty) {
+    // If we get here, the transaction must be a dummy batch transaction
+    // created by BeginBatch(). If it contains no children, get rid of it!
+    if (!transactionItem->NumberOfChildren()) {
+      return NS_OK;
+    }
+  }
+
+  // Check if the transaction is transient. If it is, there's nothing
+  // more to do, just return.
+  if (transaction) {
+    bool isTransient = false;
+    nsresult rv = transaction->GetIsTransient(&isTransient);
+    if (NS_FAILED(rv)) {
+      NS_WARNING("nsITransaction::GetIsTransient() failed");
+      return rv;
+    }
+    // XXX: Should we be clearing the redo stack if the transaction
+    //      is transient and there is nothing on the do stack?
+    if (isTransient) {
+      return NS_OK;
+    }
+  }
+
+  if (!mMaxTransactionCount) {
+    return NS_OK;
+  }
+
+  // Check if there is a transaction on the do stack. If there is,
+  // the current transaction is a "sub" transaction, and should
+  // be added to the transaction at the top of the do stack.
+  RefPtr<TransactionItem> topTransactionItem = mDoStack.Peek();
+  if (topTransactionItem) {
+    // XXX: What do we do if this fails?
+    nsresult rv = topTransactionItem->AddChild(*transactionItem);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                         "TransactionItem::AddChild() failed");
+    return rv;
+  }
+
+  // The transaction succeeded, so clear the redo stack.
+  mRedoStack.Clear();
+
+  // Check if we can coalesce this transaction with the one at the top
+  // of the undo stack.
+  topTransactionItem = mUndoStack.Peek();
+  if (transaction && topTransactionItem) {
+    bool didMerge = false;
+    nsCOMPtr<nsITransaction> topTransaction =
+        topTransactionItem->GetTransaction();
+    if (topTransaction) {
+      nsresult rv = topTransaction->Merge(transaction, &didMerge);
+      if (didMerge) {
+        return rv;
+      }
+      NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                           "nsITransaction::Merge() failed, but ignored");
+    }
+  }
+
+  // Check to see if we've hit the max level of undo. If so,
+  // pop the bottom transaction off the undo stack and release it!
+  int32_t sz = mUndoStack.GetSize();
+  if (mMaxTransactionCount > 0 && sz >= mMaxTransactionCount) {
+    RefPtr<TransactionItem> overflow = mUndoStack.PopBottom();
+  }
+
+  // Push the transaction on the undo stack:
+  mUndoStack.Push(transactionItem.forget());
+  return NS_OK;
+}
+
+}  // namespace mozilla
diff --git a/editor/txmgr/TransactionManager.h b/editor/txmgr/TransactionManager.h
new file mode 100644
index 0000000000..cdabc83c90
--- /dev/null
+++ b/editor/txmgr/TransactionManager.h
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#ifndef mozilla_TransactionManager_h
+#define mozilla_TransactionManager_h
+
+#include "mozilla/EditorForwards.h"
+#include "mozilla/TransactionStack.h"
+
+#include "nsCOMArray.h"
+#include "nsCOMPtr.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsISupportsImpl.h"
+#include "nsITransactionManager.h"
+#include "nsWeakReference.h"
+#include "nscore.h"
+
+class nsITransaction;
+
+namespace mozilla {
+
+class TransactionManager final : public nsITransactionManager,
+                                 public nsSupportsWeakReference {
+ public:
+  explicit TransactionManager(int32_t aMaxTransactionCount = -1);
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(TransactionManager,
+                                           nsITransactionManager)
+
+  NS_DECL_NSITRANSACTIONMANAGER
+
+  already_AddRefed<nsITransaction> PeekUndoStack();
+  already_AddRefed<nsITransaction> PeekRedoStack();
+
+  MOZ_CAN_RUN_SCRIPT nsresult Undo();
+  MOZ_CAN_RUN_SCRIPT nsresult Redo();
+
+  size_t NumberOfUndoItems() const { return mUndoStack.GetSize(); }
+  size_t NumberOfRedoItems() const { return mRedoStack.GetSize(); }
+
+  int32_t NumberOfMaximumTransactions() const { return mMaxTransactionCount; }
+
+  bool EnableUndoRedo(int32_t aMaxTransactionCount = -1);
+  bool DisableUndoRedo() { return EnableUndoRedo(0); }
+  bool ClearUndoRedo() {
+    if (NS_WARN_IF(!mDoStack.IsEmpty())) {
+      return false;
+    }
+    mUndoStack.Clear();
+    mRedoStack.Clear();
+    return true;
+  }
+
+  void Attach(HTMLEditor& aHTMLEditor);
+  void Detach(const HTMLEditor& aHTMLEditor);
+
+  MOZ_CAN_RUN_SCRIPT void DidDoNotify(nsITransaction& aTransaction,
+                                      nsresult aDoResult);
+  MOZ_CAN_RUN_SCRIPT void DidUndoNotify(nsITransaction& aTransaction,
+                                        nsresult aUndoResult);
+  MOZ_CAN_RUN_SCRIPT void DidRedoNotify(nsITransaction& aTransaction,
+                                        nsresult aRedoResult);
+
+  /**
+   * Exposing non-virtual methods of nsITransactionManager methods.
+   */
+  MOZ_CAN_RUN_SCRIPT nsresult BeginBatchInternal(nsISupports* aData);
+  nsresult EndBatchInternal(bool aAllowEmpty);
+
+ private:
+  virtual ~TransactionManager() = default;
+
+  MOZ_CAN_RUN_SCRIPT nsresult BeginTransaction(nsITransaction* aTransaction,
+                                               nsISupports* aData);
+  nsresult EndTransaction(bool aAllowEmpty);
+
+  int32_t mMaxTransactionCount;
+  TransactionStack mDoStack;
+  TransactionStack mUndoStack;
+  TransactionStack mRedoStack;
+  RefPtr<HTMLEditor> mHTMLEditor;
+};
+
+}  // namespace mozilla
+
+mozilla::TransactionManager* nsITransactionManager::AsTransactionManager() {
+  return static_cast<mozilla::TransactionManager*>(this);
+}
+
+#endif  // #ifndef mozilla_TransactionManager_h
diff --git a/editor/txmgr/TransactionStack.cpp b/editor/txmgr/TransactionStack.cpp
new file mode 100644
index 0000000000..f0d9c7d455
--- /dev/null
+++ b/editor/txmgr/TransactionStack.cpp
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "TransactionStack.h"
+
+#include "nsCycleCollectionParticipant.h"
+#include "nsDebug.h"
+#include "nsISupportsUtils.h"
+#include "nscore.h"
+#include "TransactionItem.h"
+
+namespace mozilla {
+
+TransactionStack::TransactionStack(Type aType)
+    : nsRefPtrDeque<TransactionItem>(), mType(aType) {}
+
+TransactionStack::~TransactionStack() { Clear(); }
+
+void TransactionStack::Push(TransactionItem* aTransactionItem) {
+  if (NS_WARN_IF(!aTransactionItem)) {
+    return;
+  }
+  nsRefPtrDeque<TransactionItem>::Push(aTransactionItem);
+}
+
+void TransactionStack::Push(
+    already_AddRefed<TransactionItem> aTransactionItem) {
+  TransactionItem* transactionItem = aTransactionItem.take();
+  if (NS_WARN_IF(!transactionItem)) {
+    return;
+  }
+  nsRefPtrDeque<TransactionItem>::Push(dont_AddRef(transactionItem));
+}
+
+already_AddRefed<TransactionItem> TransactionStack::Pop() {
+  return nsRefPtrDeque<TransactionItem>::Pop();
+}
+
+already_AddRefed<TransactionItem> TransactionStack::PopBottom() {
+  return nsRefPtrDeque<TransactionItem>::PopFront();
+}
+
+already_AddRefed<TransactionItem> TransactionStack::Peek() const {
+  RefPtr<TransactionItem> item = nsRefPtrDeque<TransactionItem>::Peek();
+  return item.forget();
+}
+
+already_AddRefed<TransactionItem> TransactionStack::GetItemAt(
+    size_t aIndex) const {
+  RefPtr<TransactionItem> item =
+      nsRefPtrDeque<TransactionItem>::ObjectAt(aIndex);
+  return item.forget();
+}
+
+void TransactionStack::Clear() {
+  while (GetSize()) {
+    RefPtr<TransactionItem> item = mType == FOR_UNDO ? Pop() : PopBottom();
+  }
+}
+
+void TransactionStack::DoTraverse(nsCycleCollectionTraversalCallback& cb) {
+  size_t size = GetSize();
+  for (size_t i = 0; i < size; ++i) {
+    auto* item = nsRefPtrDeque<TransactionItem>::ObjectAt(i);
+    if (item) {
+      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "transaction stack mDeque[i]");
+      cb.NoteNativeChild(item,
+                         NS_CYCLE_COLLECTION_PARTICIPANT(TransactionItem));
+    }
+  }
+}
+
+}  // namespace mozilla
diff --git a/editor/txmgr/TransactionStack.h b/editor/txmgr/TransactionStack.h
new file mode 100644
index 0000000000..74e8aebec8
--- /dev/null
+++ b/editor/txmgr/TransactionStack.h
@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#ifndef mozilla_TransactionStack_h
+#define mozilla_TransactionStack_h
+
+#include "mozilla/AlreadyAddRefed.h"
+#include "nsDeque.h"
+
+class nsCycleCollectionTraversalCallback;
+
+namespace mozilla {
+
+class TransactionItem;
+
+class TransactionStack : private nsRefPtrDeque<TransactionItem> {
+ public:
+  enum Type { FOR_UNDO, FOR_REDO };
+
+  explicit TransactionStack(Type aType);
+  ~TransactionStack();
+
+  void Push(TransactionItem* aTransactionItem);
+  void Push(already_AddRefed<TransactionItem> aTransactionItem);
+  already_AddRefed<TransactionItem> Pop();
+  already_AddRefed<TransactionItem> PopBottom();
+  already_AddRefed<TransactionItem> Peek() const;
+  already_AddRefed<TransactionItem> GetItemAt(size_t aIndex) const;
+  void Clear();
+  size_t GetSize() const { return nsRefPtrDeque<TransactionItem>::GetSize(); }
+  bool IsEmpty() const { return GetSize() == 0; }
+
+  void DoUnlink() { Clear(); }
+  void DoTraverse(nsCycleCollectionTraversalCallback& cb);
+
+ private:
+  const Type mType;
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_TransactionStack_h
diff --git a/editor/txmgr/moz.build b/editor/txmgr/moz.build
new file mode 100644
index 0000000000..f4310ab298
--- /dev/null
+++ b/editor/txmgr/moz.build
@@ -0,0 +1,31 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+TEST_DIRS += ["tests"]
+
+XPIDL_SOURCES += [
+    "nsITransaction.idl",
+    "nsITransactionManager.idl",
+]
+
+XPIDL_MODULE = "txmgr"
+
+EXPORTS += [
+    "nsTransactionManagerCID.h",
+]
+
+EXPORTS.mozilla += [
+    "TransactionManager.h",
+    "TransactionStack.h",
+]
+
+UNIFIED_SOURCES += [
+    "TransactionItem.cpp",
+    "TransactionManager.cpp",
+    "TransactionStack.cpp",
+]
+
+FINAL_LIBRARY = "xul"
diff --git a/editor/txmgr/nsITransaction.idl b/editor/txmgr/nsITransaction.idl
new file mode 100644
index 0000000000..bc8a8ed1d2
--- /dev/null
+++ b/editor/txmgr/nsITransaction.idl
@@ -0,0 +1,82 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "nsISupports.idl"
+
+%{ C++
+namespace mozilla {
+class EditTransactionBase;
+}
+template <typename T>
+struct already_AddRefed;
+%}
+
+[ptr] native EditTransactionBasePtr(mozilla::EditTransactionBase);
+
+/*
+ * The nsITransaction interface.
+ * <P>
+ * This interface is implemented by an object that needs to
+ * execute some behavior that must be tracked by the transaction manager.
+ */
+[scriptable, uuid(58e330c1-7b48-11d2-98b9-00805f297d89)]
+interface nsITransaction : nsISupports
+{
+  /**
+   * Executes the transaction.
+   */
+  [can_run_script]
+  void doTransaction();
+
+  /**
+   * Restores the state to what it was before the transaction was executed.
+   */
+  [can_run_script]
+  void undoTransaction();
+
+  /**
+   * Executes the transaction again. Can only be called on a transaction that
+   * was previously undone.
+   * <P>
+   * In most cases, the redoTransaction() method will actually call the
+   * doTransaction() method to execute the transaction again.
+   */
+  [can_run_script]
+  void redoTransaction();
+
+  /**
+   * The transaction's transient state. This attribute is checked by
+   * the transaction manager after the transaction's Execute() method is called.
+   * If the transient state is false, a reference to the transaction is
+   * held by the transaction manager so that the transactions' undoTransaction()
+   * and redoTransaction() methods can be called. If the transient state is
+   * true, the transaction manager returns immediately after the transaction's
+   * doTransaction() method is called, no references to the transaction are
+   * maintained. Transient transactions cannot be undone or redone by the
+   * transaction manager.
+   */
+  readonly attribute boolean isTransient;
+
+  /**
+   * Attempts to merge a transaction into "this" transaction. Both transactions
+   * must be in their undo state, doTransaction() methods already called. The
+   * transaction manager calls this method to coalesce a new transaction with
+   * the transaction on the top of the undo stack.
+   * This method returns a boolean value that indicates the merge result.
+   * A true value indicates that the transactions were merged successfully,
+   * a false value if the merge was not possible or failed. If true,
+   * the transaction manager will Release() the new transacton instead of
+   * pushing it on the undo stack.
+   * @param aTransaction the previously executed transaction to merge.
+   */
+  boolean merge(in nsITransaction aTransaction);
+
+  [noscript] EditTransactionBasePtr getAsEditTransactionBase();
+
+%{ C++
+  inline already_AddRefed<mozilla::EditTransactionBase>
+  GetAsEditTransactionBase();
+%}
+};
diff --git a/editor/txmgr/nsITransactionManager.idl b/editor/txmgr/nsITransactionManager.idl
new file mode 100644
index 0000000000..612071380b
--- /dev/null
+++ b/editor/txmgr/nsITransactionManager.idl
@@ -0,0 +1,148 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "nsISupports.idl"
+#include "nsITransaction.idl"
+
+%{C++
+namespace mozilla {
+class TransactionManager;
+} // namespace mozilla
+%}
+
+/**
+ * The nsITransactionManager interface.
+ * <P>
+ * This interface is implemented by an object that wants to
+ * manage/track transactions.
+ */
+[scriptable, builtinclass, uuid(c77763df-0fb9-41a8-8074-8e882f605755)]
+interface nsITransactionManager : nsISupports
+{
+  /**
+   * Calls a transaction's doTransaction() method, then pushes it on the
+   * undo stack.
+   * <P>
+   * This method calls the transaction's AddRef() method.
+   * The transaction's Release() method will be called when the undo or redo
+   * stack is pruned or when the transaction manager is destroyed.
+   * @param aTransaction the transaction to do.
+   */
+  [can_run_script]
+  void doTransaction(in nsITransaction aTransaction);
+
+  /**
+   * Pops the topmost transaction on the undo stack, calls its
+   * undoTransaction() method, then pushes it on the redo stack.
+   */
+  [can_run_script]
+  void undoTransaction();
+
+  /**
+   * Pops the topmost transaction on the redo stack, calls its
+   * redoTransaction() method, then pushes it on the undo stack.
+   */
+  [can_run_script]
+  void redoTransaction();
+
+  /**
+   * Clears the undo and redo stacks.
+   */
+  void clear();
+
+  /**
+   * Clears the undo stack only.
+   */
+  void clearUndoStack();
+
+  /**
+   * Clears the redo stack only.
+   */
+  void clearRedoStack();
+
+  /**
+   * Turns on the transaction manager's batch mode, forcing all transactions
+   * executed by the transaction manager's doTransaction() method to be
+   * aggregated together until EndBatch() is called.  This mode allows an
+   * application to execute and group together several independent transactions
+   * so they can be undone with a single call to undoTransaction().
+   * @param aData An arbitrary nsISupports object that is associated with the
+   * batch. Can be retrieved from the undo or redo stacks.
+   */
+  [can_run_script]
+  void beginBatch(in nsISupports aData);
+
+  /**
+   * Turns off the transaction manager's batch mode.
+   * @param aAllowEmpty If true, a batch containing no children will be
+   * pushed onto the undo stack. Otherwise, ending a batch with no
+   * children will result in no transactions being pushed on the undo stack.
+   */
+  void endBatch(in boolean aAllowEmpty);
+
+  /**
+   * The number of items on the undo stack.
+   */
+  readonly attribute long numberOfUndoItems;
+
+  /**
+   * The number of items on the redo stack.
+   */
+  readonly attribute long numberOfRedoItems;
+
+  /**
+   * Sets the maximum number of transaction items the transaction manager will
+   * maintain at any time. This is commonly referred to as the number of levels
+   * of undo.
+   * @param aMaxCount A value of -1 means no limit. A value of zero means the
+   * transaction manager will execute each transaction, then immediately release
+   * all references it has to the transaction without pushing it on the undo
+   * stack. A value greater than zero indicates the max number of transactions
+   * that can exist at any time on both the undo and redo stacks. This method
+   * will prune the necessary number of transactions on the undo and redo
+   * stacks if the value specified is less than the number of items that exist
+   * on both the undo and redo stacks.
+   */
+  attribute long maxTransactionCount;
+
+  /**
+   * Combines the transaction at the top of the undo stack (if any) with the
+   * preceding undo transaction (if any) into a batch transaction. Thus,
+   * a call to undoTransaction() will undo both transactions.
+   */
+  void batchTopUndo();
+
+  /**
+   * Removes the transaction at the top of the undo stack (if any) without
+   * transacting.
+   */
+  void removeTopUndo();
+
+  /**
+   * Returns an AddRef'd pointer to the transaction at the top of the
+   * undo stack. Callers should be aware that this method could return
+   * return a null in some implementations if there is a batch at the top
+   * of the undo stack.
+   */
+  nsITransaction peekUndoStack();
+
+  /**
+   * Returns an AddRef'd pointer to the transaction at the top of the
+   * redo stack. Callers should be aware that this method could return
+   * return a null in some implementations if there is a batch at the top
+   * of the redo stack.
+   */
+  nsITransaction peekRedoStack();
+
+%{C++
+  /**
+   * AsTransactionManager() returns a pointer to TransactionManager class.
+   *
+   * In order to avoid circular dependency issues, this method is defined
+   * in mozilla/TransactionManager.h.  Consumers need to #include that header.
+   */
+  inline mozilla::TransactionManager* AsTransactionManager();
+%}
+};
diff --git a/editor/txmgr/nsTransactionManagerCID.h b/editor/txmgr/nsTransactionManagerCID.h
new file mode 100644
index 0000000000..11beb737c7
--- /dev/null
+++ b/editor/txmgr/nsTransactionManagerCID.h
@@ -0,0 +1,7 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+// XXX Needs to modify mailnews/base/src/nsMsgWindow.cpp before removing this
+//     header file.
diff --git a/editor/txmgr/tests/TestTXMgr.cpp b/editor/txmgr/tests/TestTXMgr.cpp
new file mode 100644
index 0000000000..71c6cdadf4
--- /dev/null
+++ b/editor/txmgr/tests/TestTXMgr.cpp
@@ -0,0 +1,2013 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "gtest/gtest.h"
+
+#include "nsITransactionManager.h"
+#include "nsComponentManagerUtils.h"
+#include "mozilla/gtest/MozAssertions.h"
+#include "mozilla/Likely.h"
+#include "mozilla/EditTransactionBase.h"
+#include "mozilla/TransactionManager.h"
+
+using mozilla::EditTransactionBase;
+using mozilla::TransactionManager;
+
+static int32_t sConstructorCount = 0;
+static int32_t sDoCount = 0;
+static int32_t* sDoOrderArr = 0;
+static int32_t sUndoCount = 0;
+static int32_t* sUndoOrderArr = 0;
+static int32_t sRedoCount = 0;
+static int32_t* sRedoOrderArr = 0;
+
+int32_t sSimpleTestDoOrderArr[] = {
+    1,   2,   3,   4,   5,   6,   7,   8,   9,   10,  11,  12,  13,  14,  15,
+    16,  17,  18,  19,  20,  21,  22,  23,  24,  25,  26,  27,  28,  29,  30,
+    31,  32,  33,  34,  35,  36,  37,  38,  39,  40,  41,  42,  43,  44,  45,
+    46,  47,  48,  49,  50,  51,  52,  53,  54,  55,  56,  57,  58,  59,  60,
+    61,  62,  63,  64,  65,  66,  67,  68,  69,  70,  71,  72,  73,  74,  75,
+    76,  77,  78,  79,  80,  81,  82,  83,  84,  85,  86,  87,  88,  89,  90,
+    91,  92,  93,  94,  95,  96,  97,  98,  99,  100, 101, 102, 103, 104, 105,
+    106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120,
+    121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131};
+
+int32_t sSimpleTestUndoOrderArr[] = {41,  40,  39,  38,  62,  39,  38,  37,
+                                     69,  71,  70,  111, 110, 109, 108, 107,
+                                     106, 105, 104, 103, 102, 131, 130, 129,
+                                     128, 127, 126, 125, 124, 123, 122};
+
+static int32_t sSimpleTestRedoOrderArr[] = {38, 39, 70};
+
+int32_t sAggregateTestDoOrderArr[] = {
+    1,   2,   3,   4,   5,   6,   7,   8,   9,   10,  11,  12,  13,  14,  15,
+    16,  17,  18,  19,  20,  21,  22,  23,  24,  25,  26,  27,  28,  29,  30,
+    31,  32,  33,  34,  35,  36,  37,  38,  39,  40,  41,  42,  43,  44,  45,
+    46,  47,  48,  49,  50,  51,  52,  53,  54,  55,  56,  57,  58,  59,  60,
+    61,  62,  63,  64,  65,  66,  67,  68,  69,  70,  71,  72,  73,  74,  75,
+    76,  77,  78,  79,  80,  81,  82,  83,  84,  85,  86,  87,  88,  89,  90,
+    91,  92,  93,  94,  95,  96,  97,  98,  99,  100, 101, 102, 103, 104, 105,
+    106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120,
+    121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135,
+    136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150,
+    151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165,
+    166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180,
+    181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195,
+    196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210,
+    211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225,
+    226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240,
+    241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255,
+    256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270,
+    271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285,
+    286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300,
+    301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315,
+    316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330,
+    331, 332, 333, 334, 335, 336, 337, 338, 339, 340, 341, 342, 343, 344, 345,
+    346, 347, 348, 349, 350, 351, 352, 353, 354, 355, 356, 357, 358, 359, 360,
+    361, 362, 363, 364, 365, 366, 367, 368, 369, 370, 371, 372, 373, 374, 375,
+    376, 377, 378, 379, 380, 381, 382, 383, 384, 385, 386, 387, 388, 389, 390,
+    391, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404, 405,
+    406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420,
+    421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 432, 433, 434, 435,
+    436, 437, 438, 439, 440, 441, 442, 443, 444, 445, 446, 447, 448, 449, 450,
+    451, 452, 453, 454, 455, 456, 457, 458, 459, 460, 461, 462, 463, 464, 465,
+    466, 467, 468, 469, 470, 471, 472, 473, 474, 475, 476, 477, 478, 479, 480,
+    481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 495,
+    496, 497, 498, 499, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510,
+    511, 512, 513, 514, 515, 516, 517, 518, 519, 520, 521, 522, 523, 524, 525,
+    526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 537, 538, 539, 540,
+    541, 542, 543, 544, 545, 546, 547, 548, 549, 550, 551, 552, 553, 554, 555,
+    556, 557, 558, 559, 560, 561, 562, 563, 564, 565, 566, 567, 568, 569, 570,
+    571, 572, 573, 574, 575, 576, 577, 578, 579, 580, 581, 582, 583, 584, 585,
+    586, 587, 588, 589, 590, 591, 592, 593, 594, 595, 596, 597, 598, 599, 600,
+    601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615,
+    616, 617, 618, 619, 620, 621, 622, 623, 624, 625, 626, 627, 628, 629, 630,
+    631, 632, 633, 634, 635, 636, 637, 638, 639, 640, 641, 642, 643, 644, 645,
+    646, 647, 648, 649, 650, 651, 652, 653, 654, 655, 656, 657, 658, 659, 660,
+    661, 662, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674, 675,
+    676, 677, 678, 679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689, 690,
+    691, 692, 693, 694, 695, 696, 697, 698, 699, 700, 701, 702, 703, 704, 705,
+    706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, 720,
+    721, 722, 723, 724, 725, 726, 727, 728, 729, 730, 731, 732, 733, 734, 735,
+    736, 737, 738, 739, 740, 741, 742, 743, 744, 745, 746, 747, 748, 749, 750,
+    751, 752, 753, 754, 755, 756, 757, 758, 759, 760, 761, 762, 763, 764, 765,
+    766, 767, 768, 769, 770, 771, 772, 773, 774, 775, 776, 777, 778, 779, 780,
+    781, 782, 783, 784, 785, 786, 787, 788, 789, 790, 791, 792, 793, 794, 795,
+    796, 797, 798, 799, 800, 801, 802, 803, 804, 805, 806, 807, 808, 809, 810,
+    811, 812, 813, 814, 815, 816, 817, 818, 819, 820, 821, 822, 823, 824, 825,
+    826, 827, 828, 829, 830, 831, 832, 833, 834, 835, 836, 837, 838, 839, 840,
+    841, 842, 843, 844, 845, 846, 847, 848, 849, 850, 851, 852, 853, 854, 855,
+    856, 857, 858, 859, 860, 861, 862, 863, 864, 865, 866, 867, 868, 869, 870,
+    871, 872, 873, 874, 875, 876, 877, 878, 879, 880, 881, 882, 883, 884, 885,
+    886, 887, 888, 889, 890, 891, 892, 893, 894, 895, 896, 897, 898, 899, 900,
+    901, 902, 903, 904, 905, 906, 907, 908, 909, 910, 911, 912, 913};
+
+int32_t sAggregateTestUndoOrderArr[] = {
+    287, 286, 285, 284, 283, 282, 281, 280, 279, 278, 277, 276, 275, 274, 273,
+    272, 271, 270, 269, 268, 267, 266, 265, 264, 263, 262, 261, 260, 434, 433,
+    432, 431, 430, 429, 428, 273, 272, 271, 270, 269, 268, 267, 266, 265, 264,
+    263, 262, 261, 260, 259, 258, 257, 256, 255, 254, 253, 479, 478, 477, 476,
+    475, 493, 492, 491, 490, 489, 488, 487, 486, 485, 484, 483, 482, 481, 480,
+    485, 484, 483, 482, 481, 480, 773, 772, 771, 770, 769, 768, 767, 766, 765,
+    764, 763, 762, 761, 760, 759, 758, 757, 756, 755, 754, 753, 752, 751, 750,
+    749, 748, 747, 746, 745, 744, 743, 742, 741, 740, 739, 738, 737, 736, 735,
+    734, 733, 732, 731, 730, 729, 728, 727, 726, 725, 724, 723, 722, 721, 720,
+    719, 718, 717, 716, 715, 714, 713, 712, 711, 710, 709, 708, 707, 706, 705,
+    704, 913, 912, 911, 910, 909, 908, 907, 906, 905, 904, 903, 902, 901, 900,
+    899, 898, 897, 896, 895, 894, 893, 892, 891, 890, 889, 888, 887, 886, 885,
+    884, 883, 882, 881, 880, 879, 878, 877, 876, 875, 874, 873, 872, 871, 870,
+    869, 868, 867, 866, 865, 864, 863, 862, 861, 860, 859, 858, 857, 856, 855,
+    854, 853, 852, 851, 850, 849, 848, 847, 846, 845, 844};
+
+int32_t sAggregateTestRedoOrderArr[] = {
+    260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272,
+    273, 476, 477, 478, 479, 480, 481, 482, 483, 484, 485, 486};
+
+int32_t sSimpleBatchTestDoOrderArr[] = {
+    1,  2,  3,  4,   5,   6,   7,   8,   9,   10,  11, 12, 13, 14, 15, 16,
+    17, 18, 19, 20,  21,  22,  23,  24,  25,  26,  27, 28, 29, 30, 31, 32,
+    33, 34, 35, 36,  37,  38,  39,  40,  41,  42,  43, 44, 45, 46, 47, 48,
+    49, 50, 51, 52,  53,  54,  55,  56,  57,  58,  59, 60, 61, 62, 63, 64,
+    65, 66, 67, 68,  69,  70,  71,  72,  73,  74,  75, 76, 77, 78, 79, 80,
+    81, 82, 83, 84,  85,  86,  87,  88,  89,  90,  91, 92, 93, 94, 95, 96,
+    97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107};
+
+int32_t sSimpleBatchTestUndoOrderArr[] = {
+    43, 42, 41, 20, 19,  18,  17,  16,  15,  14,  13,  12,  11, 10, 9,
+    8,  7,  6,  5,  4,   3,   2,   1,   43,  42,  41,  63,  62, 61, 60,
+    59, 58, 57, 56, 55,  54,  53,  52,  51,  50,  49,  48,  47, 46, 45,
+    44, 65, 67, 66, 107, 106, 105, 104, 103, 102, 101, 100, 99, 98};
+
+int32_t sSimpleBatchTestRedoOrderArr[] = {1,  2,  3,  4,  5,  6,  7,  8,
+                                          9,  10, 11, 12, 13, 14, 15, 16,
+                                          17, 18, 19, 20, 41, 42, 43, 66};
+
+int32_t sAggregateBatchTestDoOrderArr[] = {
+    1,   2,   3,   4,   5,   6,   7,   8,   9,   10,  11,  12,  13,  14,  15,
+    16,  17,  18,  19,  20,  21,  22,  23,  24,  25,  26,  27,  28,  29,  30,
+    31,  32,  33,  34,  35,  36,  37,  38,  39,  40,  41,  42,  43,  44,  45,
+    46,  47,  48,  49,  50,  51,  52,  53,  54,  55,  56,  57,  58,  59,  60,
+    61,  62,  63,  64,  65,  66,  67,  68,  69,  70,  71,  72,  73,  74,  75,
+    76,  77,  78,  79,  80,  81,  82,  83,  84,  85,  86,  87,  88,  89,  90,
+    91,  92,  93,  94,  95,  96,  97,  98,  99,  100, 101, 102, 103, 104, 105,
+    106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120,
+    121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135,
+    136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150,
+    151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165,
+    166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180,
+    181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195,
+    196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210,
+    211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225,
+    226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240,
+    241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255,
+    256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270,
+    271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285,
+    286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300,
+    301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315,
+    316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330,
+    331, 332, 333, 334, 335, 336, 337, 338, 339, 340, 341, 342, 343, 344, 345,
+    346, 347, 348, 349, 350, 351, 352, 353, 354, 355, 356, 357, 358, 359, 360,
+    361, 362, 363, 364, 365, 366, 367, 368, 369, 370, 371, 372, 373, 374, 375,
+    376, 377, 378, 379, 380, 381, 382, 383, 384, 385, 386, 387, 388, 389, 390,
+    391, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404, 405,
+    406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420,
+    421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 432, 433, 434, 435,
+    436, 437, 438, 439, 440, 441, 442, 443, 444, 445, 446, 447, 448, 449, 450,
+    451, 452, 453, 454, 455, 456, 457, 458, 459, 460, 461, 462, 463, 464, 465,
+    466, 467, 468, 469, 470, 471, 472, 473, 474, 475, 476, 477, 478, 479, 480,
+    481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 495,
+    496, 497, 498, 499, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510,
+    511, 512, 513, 514, 515, 516, 517, 518, 519, 520, 521, 522, 523, 524, 525,
+    526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 537, 538, 539, 540,
+    541, 542, 543, 544, 545, 546, 547, 548, 549, 550, 551, 552, 553, 554, 555,
+    556, 557, 558, 559, 560, 561, 562, 563, 564, 565, 566, 567, 568, 569, 570,
+    571, 572, 573, 574, 575, 576, 577, 578, 579, 580, 581, 582, 583, 584, 585,
+    586, 587, 588, 589, 590, 591, 592, 593, 594, 595, 596, 597, 598, 599, 600,
+    601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615,
+    616, 617, 618, 619, 620, 621, 622, 623, 624, 625, 626, 627, 628, 629, 630,
+    631, 632, 633, 634, 635, 636, 637, 638, 639, 640, 641, 642, 643, 644, 645,
+    646, 647, 648, 649, 650, 651, 652, 653, 654, 655, 656, 657, 658, 659, 660,
+    661, 662, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674, 675,
+    676, 677, 678, 679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689, 690,
+    691, 692, 693, 694, 695, 696, 697, 698, 699, 700, 701, 702, 703, 704, 705,
+    706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, 720,
+    721, 722, 723, 724, 725, 726, 727, 728, 729, 730, 731, 732, 733, 734, 735,
+    736, 737, 738, 739, 740, 741, 742, 743, 744, 745};
+
+int32_t sAggregateBatchTestUndoOrderArr[] = {
+    301, 300, 299, 298, 297, 296, 295, 294, 293, 292, 291, 290, 289, 288, 287,
+    286, 285, 284, 283, 282, 281, 140, 139, 138, 137, 136, 135, 134, 133, 132,
+    131, 130, 129, 128, 127, 126, 125, 124, 123, 122, 121, 120, 119, 118, 117,
+    116, 115, 114, 113, 112, 111, 110, 109, 108, 107, 106, 105, 104, 103, 102,
+    101, 100, 99,  98,  97,  96,  95,  94,  93,  92,  91,  90,  89,  88,  87,
+    86,  85,  84,  83,  82,  81,  80,  79,  78,  77,  76,  75,  74,  73,  72,
+    71,  70,  69,  68,  67,  66,  65,  64,  63,  62,  61,  60,  59,  58,  57,
+    56,  55,  54,  53,  52,  51,  50,  49,  48,  47,  46,  45,  44,  43,  42,
+    41,  40,  39,  38,  37,  36,  35,  34,  33,  32,  31,  30,  29,  28,  27,
+    26,  25,  24,  23,  22,  21,  20,  19,  18,  17,  16,  15,  14,  13,  12,
+    11,  10,  9,   8,   7,   6,   5,   4,   3,   2,   1,   301, 300, 299, 298,
+    297, 296, 295, 294, 293, 292, 291, 290, 289, 288, 287, 286, 285, 284, 283,
+    282, 281, 441, 440, 439, 438, 437, 436, 435, 434, 433, 432, 431, 430, 429,
+    428, 427, 426, 425, 424, 423, 422, 421, 420, 419, 418, 417, 416, 415, 414,
+    413, 412, 411, 410, 409, 408, 407, 406, 405, 404, 403, 402, 401, 400, 399,
+    398, 397, 396, 395, 394, 393, 392, 391, 390, 389, 388, 387, 386, 385, 384,
+    383, 382, 381, 380, 379, 378, 377, 376, 375, 374, 373, 372, 371, 370, 369,
+    368, 367, 366, 365, 364, 363, 362, 361, 360, 359, 358, 357, 356, 355, 354,
+    353, 352, 351, 350, 349, 348, 347, 346, 345, 344, 343, 342, 341, 340, 339,
+    338, 337, 336, 335, 334, 333, 332, 331, 330, 329, 328, 327, 326, 325, 324,
+    323, 322, 321, 320, 319, 318, 317, 316, 315, 314, 313, 312, 311, 310, 309,
+    308, 307, 306, 305, 304, 303, 302, 451, 450, 449, 448, 447, 465, 464, 463,
+    462, 461, 460, 459, 458, 457, 456, 455, 454, 453, 452, 457, 456, 455, 454,
+    453, 452, 745, 744, 743, 742, 741, 740, 739, 738, 737, 736, 735, 734, 733,
+    732, 731, 730, 729, 728, 727, 726, 725, 724, 723, 722, 721, 720, 719, 718,
+    717, 716, 715, 714, 713, 712, 711, 710, 709, 708, 707, 706, 705, 704, 703,
+    702, 701, 700, 699, 698, 697, 696, 695, 694, 693, 692, 691, 690, 689, 688,
+    687, 686, 685, 684, 683, 682, 681, 680, 679, 678, 677, 676};
+
+int32_t sAggregateBatchTestRedoOrderArr[] = {
+    1,   2,   3,   4,   5,   6,   7,   8,   9,   10,  11,  12,  13,  14,  15,
+    16,  17,  18,  19,  20,  21,  22,  23,  24,  25,  26,  27,  28,  29,  30,
+    31,  32,  33,  34,  35,  36,  37,  38,  39,  40,  41,  42,  43,  44,  45,
+    46,  47,  48,  49,  50,  51,  52,  53,  54,  55,  56,  57,  58,  59,  60,
+    61,  62,  63,  64,  65,  66,  67,  68,  69,  70,  71,  72,  73,  74,  75,
+    76,  77,  78,  79,  80,  81,  82,  83,  84,  85,  86,  87,  88,  89,  90,
+    91,  92,  93,  94,  95,  96,  97,  98,  99,  100, 101, 102, 103, 104, 105,
+    106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120,
+    121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135,
+    136, 137, 138, 139, 140, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290,
+    291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 301, 448, 449, 450, 451,
+    452, 453, 454, 455, 456, 457, 458};
+
+class TestTransaction : public nsITransaction {
+ protected:
+  virtual ~TestTransaction() = default;
+
+ public:
+  TestTransaction() {}
+
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD GetAsEditTransactionBase(EditTransactionBase**) final {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+};
+
+NS_IMPL_ISUPPORTS(TestTransaction, nsITransaction)
+
+class SimpleTransaction : public TestTransaction {
+ protected:
+#define NONE_FLAG 0
+#define THROWS_DO_ERROR_FLAG 1
+#define THROWS_UNDO_ERROR_FLAG 2
+#define THROWS_REDO_ERROR_FLAG 4
+#define MERGE_FLAG 8
+#define TRANSIENT_FLAG 16
+#define BATCH_FLAG 32
+#define ALL_ERROR_FLAGS \
+  (THROWS_DO_ERROR_FLAG | THROWS_UNDO_ERROR_FLAG | THROWS_REDO_ERROR_FLAG)
+
+  int32_t mVal;
+  int32_t mFlags;
+
+ public:
+  explicit SimpleTransaction(int32_t aFlags = NONE_FLAG)
+      : mVal(++sConstructorCount), mFlags(aFlags) {}
+
+  ~SimpleTransaction() override = default;
+
+  MOZ_CAN_RUN_SCRIPT NS_IMETHOD DoTransaction() override {
+    //
+    // Make sure DoTransaction() is called in the order we expect!
+    // Notice that we don't check to see if we go past the end of the array.
+    // This is done on purpose since we want to crash if the order array is out
+    // of date.
+    //
+    if (sDoOrderArr) {
+      EXPECT_EQ(mVal, sDoOrderArr[sDoCount]);
+    }
+
+    ++sDoCount;
+
+    return (mFlags & THROWS_DO_ERROR_FLAG) ? NS_ERROR_FAILURE : NS_OK;
+  }
+
+  MOZ_CAN_RUN_SCRIPT NS_IMETHOD UndoTransaction() override {
+    //
+    // Make sure UndoTransaction() is called in the order we expect!
+    // Notice that we don't check to see if we go past the end of the array.
+    // This is done on purpose since we want to crash if the order array is out
+    // of date.
+    //
+    if (sUndoOrderArr) {
+      EXPECT_EQ(mVal, sUndoOrderArr[sUndoCount]);
+    }
+
+    ++sUndoCount;
+
+    return (mFlags & THROWS_UNDO_ERROR_FLAG) ? NS_ERROR_FAILURE : NS_OK;
+  }
+
+  MOZ_CAN_RUN_SCRIPT NS_IMETHOD RedoTransaction() override {
+    //
+    // Make sure RedoTransaction() is called in the order we expect!
+    // Notice that we don't check to see if we go past the end of the array.
+    // This is done on purpose since we want to crash if the order array is out
+    // of date.
+    //
+    if (sRedoOrderArr) {
+      EXPECT_EQ(mVal, sRedoOrderArr[sRedoCount]);
+    }
+
+    ++sRedoCount;
+
+    return (mFlags & THROWS_REDO_ERROR_FLAG) ? NS_ERROR_FAILURE : NS_OK;
+  }
+
+  NS_IMETHOD GetIsTransient(bool* aIsTransient) override {
+    if (aIsTransient) {
+      *aIsTransient = (mFlags & TRANSIENT_FLAG) ? true : false;
+    }
+    return NS_OK;
+  }
+
+  NS_IMETHOD Merge(nsITransaction* aTransaction, bool* aDidMerge) override {
+    if (aDidMerge) {
+      *aDidMerge = (mFlags & MERGE_FLAG) ? true : false;
+    }
+    return NS_OK;
+  }
+};
+
+class AggregateTransaction : public SimpleTransaction {
+ private:
+  AggregateTransaction(nsITransactionManager* aTXMgr, int32_t aLevel,
+                       int32_t aNumber, int32_t aMaxLevel,
+                       int32_t aNumChildrenPerNode, int32_t aFlags) {
+    mLevel = aLevel;
+    mNumber = aNumber;
+    mTXMgr = aTXMgr;
+    mFlags = aFlags & (~ALL_ERROR_FLAGS);
+    mErrorFlags = aFlags & ALL_ERROR_FLAGS;
+    mTXMgr = aTXMgr;
+    mMaxLevel = aMaxLevel;
+    mNumChildrenPerNode = aNumChildrenPerNode;
+  }
+
+  nsITransactionManager* mTXMgr;
+
+  int32_t mLevel;
+  int32_t mNumber;
+  int32_t mErrorFlags;
+
+  int32_t mMaxLevel;
+  int32_t mNumChildrenPerNode;
+
+ public:
+  AggregateTransaction(nsITransactionManager* aTXMgr, int32_t aMaxLevel,
+                       int32_t aNumChildrenPerNode,
+                       int32_t aFlags = NONE_FLAG) {
+    mLevel = 1;
+    mNumber = 1;
+    mFlags = aFlags & (~ALL_ERROR_FLAGS);
+    mErrorFlags = aFlags & ALL_ERROR_FLAGS;
+    mTXMgr = aTXMgr;
+    mMaxLevel = aMaxLevel;
+    mNumChildrenPerNode = aNumChildrenPerNode;
+  }
+
+  ~AggregateTransaction() override = default;
+
+  MOZ_CAN_RUN_SCRIPT NS_IMETHOD DoTransaction() override {
+    if (mLevel >= mMaxLevel) {
+      // Only leaf nodes can throw errors!
+      mFlags |= mErrorFlags;
+    }
+
+    nsresult rv = SimpleTransaction::DoTransaction();
+    if (NS_FAILED(rv)) {
+      // fail("QueryInterface() failed for transaction level %d. (%d)\n",
+      //      mLevel, rv);
+      return rv;
+    }
+
+    if (mLevel >= mMaxLevel) {
+      return NS_OK;
+    }
+
+    if (mFlags & BATCH_FLAG) {
+      rv = MOZ_KnownLive(mTXMgr)->BeginBatch(nullptr);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+    }
+
+    int32_t cLevel = mLevel + 1;
+
+    for (int i = 1; i <= mNumChildrenPerNode; i++) {
+      int32_t flags = mErrorFlags & THROWS_DO_ERROR_FLAG;
+
+      if ((mErrorFlags & THROWS_REDO_ERROR_FLAG) && i == mNumChildrenPerNode) {
+        // Make the rightmost leaf transaction throw the error!
+        flags = THROWS_REDO_ERROR_FLAG;
+        mErrorFlags = mErrorFlags & (~THROWS_REDO_ERROR_FLAG);
+      } else if ((mErrorFlags & THROWS_UNDO_ERROR_FLAG) && i == 1) {
+        // Make the leftmost leaf transaction throw the error!
+        flags = THROWS_UNDO_ERROR_FLAG;
+        mErrorFlags = mErrorFlags & (~THROWS_UNDO_ERROR_FLAG);
+      }
+
+      flags |= mFlags & BATCH_FLAG;
+
+      RefPtr<AggregateTransaction> tximpl = new AggregateTransaction(
+          mTXMgr, cLevel, i, mMaxLevel, mNumChildrenPerNode, flags);
+
+      rv = MOZ_KnownLive(mTXMgr)->DoTransaction(tximpl);
+      if (NS_FAILED(rv)) {
+        if (mFlags & BATCH_FLAG) {
+          mTXMgr->EndBatch(false);
+        }
+        return rv;
+      }
+    }
+
+    if (mFlags & BATCH_FLAG) {
+      mTXMgr->EndBatch(false);
+    }
+    return rv;
+  }
+};
+
+class TestTransactionFactory {
+ public:
+  virtual TestTransaction* create(nsITransactionManager* txmgr,
+                                  int32_t flags) = 0;
+};
+
+class SimpleTransactionFactory : public TestTransactionFactory {
+ public:
+  TestTransaction* create(nsITransactionManager* txmgr,
+                          int32_t flags) override {
+    return (TestTransaction*)new SimpleTransaction(flags);
+  }
+};
+
+class AggregateTransactionFactory : public TestTransactionFactory {
+ private:
+  int32_t mMaxLevel;
+  int32_t mNumChildrenPerNode;
+  int32_t mFixedFlags;
+
+ public:
+  AggregateTransactionFactory(int32_t aMaxLevel, int32_t aNumChildrenPerNode,
+                              int32_t aFixedFlags = NONE_FLAG)
+      : mMaxLevel(aMaxLevel),
+        mNumChildrenPerNode(aNumChildrenPerNode),
+        mFixedFlags(aFixedFlags) {}
+
+  TestTransaction* create(nsITransactionManager* txmgr,
+                          int32_t flags) override {
+    return (TestTransaction*)new AggregateTransaction(
+        txmgr, mMaxLevel, mNumChildrenPerNode, flags | mFixedFlags);
+  }
+};
+
+void reset_globals() {
+  sConstructorCount = 0;
+
+  sDoCount = 0;
+  sDoOrderArr = 0;
+
+  sUndoCount = 0;
+  sUndoOrderArr = 0;
+
+  sRedoCount = 0;
+  sRedoOrderArr = 0;
+}
+
+/**
+ * Test behaviors in non-batch mode.
+ **/
+MOZ_CAN_RUN_SCRIPT_BOUNDARY void quick_test(TestTransactionFactory* factory) {
+  /*******************************************************************
+   *
+   * Create a transaction manager implementation:
+   *
+   *******************************************************************/
+
+  nsCOMPtr<nsITransactionManager> mgr = new TransactionManager();
+
+  /*******************************************************************
+   *
+   * Call DoTransaction() with a null transaction:
+   *
+   *******************************************************************/
+
+  nsresult rv = mgr->DoTransaction(nullptr);
+  EXPECT_EQ(rv, NS_ERROR_NULL_POINTER);
+
+  /*******************************************************************
+   *
+   * Call UndoTransaction() with an empty undo stack:
+   *
+   *******************************************************************/
+
+  rv = mgr->UndoTransaction();
+  EXPECT_NS_SUCCEEDED(rv);
+
+  /*******************************************************************
+   *
+   * Call RedoTransaction() with an empty redo stack:
+   *
+   *******************************************************************/
+
+  rv = mgr->RedoTransaction();
+  EXPECT_NS_SUCCEEDED(rv);
+
+  /*******************************************************************
+   *
+   * Call SetMaxTransactionCount(-1) with empty undo and redo stacks:
+   *
+   *******************************************************************/
+
+  rv = mgr->SetMaxTransactionCount(-1);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  /*******************************************************************
+   *
+   * Call SetMaxTransactionCount(0) with empty undo and redo stacks:
+   *
+   *******************************************************************/
+
+  rv = mgr->SetMaxTransactionCount(0);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  /*******************************************************************
+   *
+   * Call SetMaxTransactionCount(10) with empty undo and redo stacks:
+   *
+   *******************************************************************/
+
+  rv = mgr->SetMaxTransactionCount(10);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  /*******************************************************************
+   *
+   * Call Clear() with empty undo and redo stacks:
+   *
+   *******************************************************************/
+
+  rv = mgr->Clear();
+  EXPECT_NS_SUCCEEDED(rv);
+
+  /*******************************************************************
+   *
+   * Call GetNumberOfUndoItems() with an empty undo stack:
+   *
+   *******************************************************************/
+
+  int32_t numitems;
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Call GetNumberOfRedoItems() with an empty redo stack:
+   *
+   *******************************************************************/
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Call PeekUndoStack() with an empty undo stack:
+   *
+   *******************************************************************/
+
+  {
+    nsCOMPtr<nsITransaction> tx;
+    rv = mgr->PeekUndoStack(getter_AddRefs(tx));
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(tx, nullptr);
+  }
+
+  /*******************************************************************
+   *
+   * Call PeekRedoStack() with an empty undo stack:
+   *
+   *******************************************************************/
+
+  {
+    nsCOMPtr<nsITransaction> tx;
+    rv = mgr->PeekRedoStack(getter_AddRefs(tx));
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(tx, nullptr);
+  }
+
+  /*******************************************************************
+   *
+   * Test coalescing by executing a transaction that can merge any
+   * command into itself. Then execute 20 transaction. Afterwards,
+   * we should still have the first transaction sitting on the undo
+   * stack. Then clear the undo and redo stacks.
+   *
+   *******************************************************************/
+
+  int32_t i;
+  RefPtr<TestTransaction> tximpl;
+  nsCOMPtr<nsITransaction> u1, u2, r1, r2;
+
+  rv = mgr->SetMaxTransactionCount(10);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  tximpl = factory->create(mgr, MERGE_FLAG);
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, tximpl);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, NONE_FLAG);
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  rv = mgr->Clear();
+  EXPECT_NS_SUCCEEDED(rv);
+
+  /*******************************************************************
+   *
+   * Execute 20 transactions. Afterwards, we should have 10
+   * transactions on the undo stack:
+   *
+   *******************************************************************/
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, NONE_FLAG);
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Execute 20 transient transactions. Afterwards, we should still
+   * have the same 10 transactions on the undo stack:
+   *
+   *******************************************************************/
+
+  u1 = u2 = r1 = r2 = nullptr;
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, TRANSIENT_FLAG);
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Undo 4 transactions. Afterwards, we should have 6 transactions
+   * on the undo stack, and 4 on the redo stack:
+   *
+   *******************************************************************/
+
+  for (i = 1; i <= 4; i++) {
+    rv = mgr->UndoTransaction();
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 6);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 4);
+
+  /*******************************************************************
+   *
+   * Redo 2 transactions. Afterwards, we should have 8 transactions
+   * on the undo stack, and 2 on the redo stack:
+   *
+   *******************************************************************/
+
+  for (i = 1; i <= 2; ++i) {
+    rv = mgr->RedoTransaction();
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 8);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 2);
+
+  /*******************************************************************
+   *
+   * Execute a new transaction. The redo stack should get pruned!
+   *
+   *******************************************************************/
+
+  tximpl = factory->create(mgr, NONE_FLAG);
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 9);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Undo 4 transactions then clear the undo and redo stacks.
+   *
+   *******************************************************************/
+
+  for (i = 1; i <= 4; ++i) {
+    rv = mgr->UndoTransaction();
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 5);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 4);
+
+  rv = mgr->Clear();
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Execute 5 transactions.
+   *
+   *******************************************************************/
+
+  for (i = 1; i <= 5; i++) {
+    tximpl = factory->create(mgr, NONE_FLAG);
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 5);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Test transaction DoTransaction() error:
+   *
+   *******************************************************************/
+
+  tximpl = factory->create(mgr, THROWS_DO_ERROR_FLAG);
+
+  u1 = u2 = r1 = r2 = nullptr;
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_EQ(rv, NS_ERROR_FAILURE);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 5);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Test transaction UndoTransaction() error:
+   *
+   *******************************************************************/
+
+  tximpl = factory->create(mgr, THROWS_UNDO_ERROR_FLAG);
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  u1 = u2 = r1 = r2 = nullptr;
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->UndoTransaction();
+  EXPECT_EQ(rv, NS_ERROR_FAILURE);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 6);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Test transaction RedoTransaction() error:
+   *
+   *******************************************************************/
+
+  tximpl = factory->create(mgr, THROWS_REDO_ERROR_FLAG);
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  //
+  // Execute a normal transaction to be used in a later test:
+  //
+
+  tximpl = factory->create(mgr, NONE_FLAG);
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  //
+  // Undo the 2 transactions just executed.
+  //
+
+  for (i = 1; i <= 2; ++i) {
+    rv = mgr->UndoTransaction();
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  //
+  // The RedoErrorTransaction should now be at the top of the redo stack!
+  //
+
+  u1 = u2 = r1 = r2 = nullptr;
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->RedoTransaction();
+  EXPECT_EQ(rv, NS_ERROR_FAILURE);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 6);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 2);
+
+  /*******************************************************************
+   *
+   * Make sure that setting the transaction manager's max transaction
+   * count to zero, clears both the undo and redo stacks, and executes
+   * all new commands without pushing them on the undo stack!
+   *
+   *******************************************************************/
+
+  rv = mgr->SetMaxTransactionCount(0);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, NONE_FLAG);
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+
+    rv = mgr->GetNumberOfUndoItems(&numitems);
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(numitems, 0);
+
+    rv = mgr->GetNumberOfRedoItems(&numitems);
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(numitems, 0);
+  }
+
+  /*******************************************************************
+   *
+   * Make sure that setting the transaction manager's max transaction
+   * count to something greater than the number of transactions on
+   * both the undo and redo stacks causes no pruning of the stacks:
+   *
+   *******************************************************************/
+
+  rv = mgr->SetMaxTransactionCount(-1);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  // Push 20 transactions on the undo stack:
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, NONE_FLAG);
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+
+    rv = mgr->GetNumberOfUndoItems(&numitems);
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(numitems, i);
+
+    rv = mgr->GetNumberOfRedoItems(&numitems);
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(numitems, 0);
+  }
+
+  for (i = 1; i <= 10; i++) {
+    rv = mgr->UndoTransaction();
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  u1 = u2 = r1 = r2 = nullptr;
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->SetMaxTransactionCount(25);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  /*******************************************************************
+   *
+   * Test undo stack pruning by setting the transaction
+   * manager's max transaction count to a number lower than the
+   * number of transactions on both the undo and redo stacks:
+   *
+   *******************************************************************/
+
+  u1 = u2 = r1 = r2 = nullptr;
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->SetMaxTransactionCount(15);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 5);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  /*******************************************************************
+   *
+   * Test redo stack pruning by setting the transaction
+   * manager's max transaction count to a number lower than the
+   * number of transactions on both the undo and redo stacks:
+   *
+   *******************************************************************/
+
+  u1 = u2 = r1 = r2 = nullptr;
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->SetMaxTransactionCount(5);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_FALSE(u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 5);
+
+  /*******************************************************************
+   *
+   * Release the transaction manager. Any transactions on the undo
+   * and redo stack should automatically be released:
+   *
+   *******************************************************************/
+
+  rv = mgr->SetMaxTransactionCount(-1);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  // Push 20 transactions on the undo stack:
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, NONE_FLAG);
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+
+    rv = mgr->GetNumberOfUndoItems(&numitems);
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(numitems, i);
+
+    rv = mgr->GetNumberOfRedoItems(&numitems);
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(numitems, 0);
+  }
+
+  for (i = 1; i <= 10; i++) {
+    rv = mgr->UndoTransaction();
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  rv = mgr->Clear();
+  EXPECT_NS_SUCCEEDED(rv);
+}
+
+TEST(TestTXMgr, SimpleTest)
+{
+  /*******************************************************************
+   *
+   * Initialize globals for test.
+   *
+   *******************************************************************/
+  reset_globals();
+  sDoOrderArr = sSimpleTestDoOrderArr;
+  sUndoOrderArr = sSimpleTestUndoOrderArr;
+  sRedoOrderArr = sSimpleTestRedoOrderArr;
+
+  /*******************************************************************
+   *
+   * Run the quick test.
+   *
+   *******************************************************************/
+
+  SimpleTransactionFactory factory;
+
+  quick_test(&factory);
+}
+
+TEST(TestTXMgr, AggregationTest)
+{
+  /*******************************************************************
+   *
+   * Initialize globals for test.
+   *
+   *******************************************************************/
+
+  reset_globals();
+  sDoOrderArr = sAggregateTestDoOrderArr;
+  sUndoOrderArr = sAggregateTestUndoOrderArr;
+  sRedoOrderArr = sAggregateTestRedoOrderArr;
+
+  /*******************************************************************
+   *
+   * Run the quick test.
+   *
+   *******************************************************************/
+
+  AggregateTransactionFactory factory(3, 2);
+
+  quick_test(&factory);
+}
+
+/**
+ * Test behaviors in batch mode.
+ **/
+MOZ_CAN_RUN_SCRIPT_BOUNDARY void quick_batch_test(
+    TestTransactionFactory* factory) {
+  /*******************************************************************
+   *
+   * Create a transaction manager implementation:
+   *
+   *******************************************************************/
+
+  nsCOMPtr<nsITransactionManager> mgr = new TransactionManager();
+
+  int32_t numitems;
+
+  /*******************************************************************
+   *
+   * Make sure an unbalanced call to EndBatch(false) with empty undo stack
+   * throws an error!
+   *
+   *******************************************************************/
+
+  nsresult rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_EQ(rv, NS_ERROR_FAILURE);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Make sure that an empty batch is not added to the undo stack
+   * when it is closed.
+   *
+   *******************************************************************/
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  int32_t i;
+  RefPtr<TestTransaction> tximpl;
+
+  /*******************************************************************
+   *
+   * Execute 20 transactions. Afterwards, we should have 1
+   * transaction on the undo stack:
+   *
+   *******************************************************************/
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, NONE_FLAG);
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  nsCOMPtr<nsITransaction> u1, u2, r1, r2;
+
+  /*******************************************************************
+   *
+   * Execute 20 transient transactions. Afterwards, we should still
+   * have the same transaction on the undo stack:
+   *
+   *******************************************************************/
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, TRANSIENT_FLAG);
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Test nested batching. Afterwards, we should have 2 transactions
+   * on the undo stack:
+   *
+   *******************************************************************/
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  tximpl = factory->create(mgr, NONE_FLAG);
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  tximpl = factory->create(mgr, NONE_FLAG);
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  tximpl = factory->create(mgr, NONE_FLAG);
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 2);
+
+  /*******************************************************************
+   *
+   * Undo 2 batch transactions. Afterwards, we should have 0
+   * transactions on the undo stack and 2 on the redo stack.
+   *
+   *******************************************************************/
+
+  for (i = 1; i <= 2; ++i) {
+    rv = mgr->UndoTransaction();
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 2);
+
+  /*******************************************************************
+   *
+   * Redo 2 batch transactions. Afterwards, we should have 2
+   * transactions on the undo stack and 0 on the redo stack.
+   *
+   *******************************************************************/
+
+  for (i = 1; i <= 2; ++i) {
+    rv = mgr->RedoTransaction();
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 2);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Call undo. Afterwards, we should have 1 transaction
+   * on the undo stack, and 1 on the redo stack:
+   *
+   *******************************************************************/
+
+  rv = mgr->UndoTransaction();
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  /*******************************************************************
+   *
+   * Make sure an unbalanced call to EndBatch(false) throws an error and
+   * doesn't affect the undo and redo stacks!
+   *
+   *******************************************************************/
+
+  rv = mgr->EndBatch(false);
+  EXPECT_EQ(rv, NS_ERROR_FAILURE);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  /*******************************************************************
+   *
+   * Make sure that an empty batch is not added to the undo stack
+   * when it is closed, and that it does not affect the undo and redo
+   * stacks.
+   *
+   *******************************************************************/
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  /*******************************************************************
+   *
+   * Execute a new transaction. The redo stack should get pruned!
+   *
+   *******************************************************************/
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, NONE_FLAG);
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 2);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Call undo.
+   *
+   *******************************************************************/
+
+  // Move a transaction over to the redo stack, so that we have one
+  // transaction on the undo stack, and one on the redo stack!
+
+  rv = mgr->UndoTransaction();
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  /*******************************************************************
+   *
+   * Test transaction DoTransaction() error:
+   *
+   *******************************************************************/
+
+  tximpl = factory->create(mgr, THROWS_DO_ERROR_FLAG);
+
+  u1 = u2 = r1 = r2 = nullptr;
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_EQ(rv, NS_ERROR_FAILURE);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 1);
+
+  /*******************************************************************
+   *
+   * Test transaction UndoTransaction() error:
+   *
+   *******************************************************************/
+
+  tximpl = factory->create(mgr, THROWS_UNDO_ERROR_FLAG);
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  u1 = u2 = r1 = r2 = nullptr;
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->UndoTransaction();
+  EXPECT_EQ(rv, NS_ERROR_FAILURE);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 2);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  /*******************************************************************
+   *
+   * Test transaction RedoTransaction() error:
+   *
+   *******************************************************************/
+
+  tximpl = factory->create(mgr, THROWS_REDO_ERROR_FLAG);
+
+  rv = mgr->BeginBatch(nullptr);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->EndBatch(false);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  //
+  // Execute a normal transaction to be used in a later test:
+  //
+
+  tximpl = factory->create(mgr, NONE_FLAG);
+  rv = mgr->DoTransaction(tximpl);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  //
+  // Undo the 2 transactions just executed.
+  //
+
+  for (i = 1; i <= 2; ++i) {
+    rv = mgr->UndoTransaction();
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+
+  //
+  // The RedoErrorTransaction should now be at the top of the redo stack!
+  //
+
+  u1 = u2 = r1 = r2 = nullptr;
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r1));
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->RedoTransaction();
+  EXPECT_EQ(rv, NS_ERROR_FAILURE);
+
+  rv = mgr->PeekUndoStack(getter_AddRefs(u2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(u1, u2);
+
+  rv = mgr->PeekRedoStack(getter_AddRefs(r2));
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(r1, r2);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 2);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 2);
+
+  /*******************************************************************
+   *
+   * Make sure that setting the transaction manager's max transaction
+   * count to zero, clears both the undo and redo stacks, and executes
+   * all new commands without pushing them on the undo stack!
+   *
+   *******************************************************************/
+
+  rv = mgr->SetMaxTransactionCount(0);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 0);
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, NONE_FLAG);
+
+    rv = mgr->BeginBatch(nullptr);
+    EXPECT_NS_SUCCEEDED(rv);
+
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+
+    rv = mgr->EndBatch(false);
+    EXPECT_NS_SUCCEEDED(rv);
+
+    rv = mgr->GetNumberOfUndoItems(&numitems);
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(numitems, 0);
+
+    rv = mgr->GetNumberOfRedoItems(&numitems);
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(numitems, 0);
+  }
+
+  /*******************************************************************
+   *
+   * Release the transaction manager. Any transactions on the undo
+   * and redo stack should automatically be released:
+   *
+   *******************************************************************/
+
+  rv = mgr->SetMaxTransactionCount(-1);
+  EXPECT_NS_SUCCEEDED(rv);
+
+  // Push 20 transactions on the undo stack:
+
+  for (i = 1; i <= 20; i++) {
+    tximpl = factory->create(mgr, NONE_FLAG);
+
+    rv = mgr->BeginBatch(nullptr);
+    EXPECT_NS_SUCCEEDED(rv);
+
+    rv = mgr->DoTransaction(tximpl);
+    EXPECT_NS_SUCCEEDED(rv);
+
+    rv = mgr->EndBatch(false);
+    EXPECT_NS_SUCCEEDED(rv);
+
+    rv = mgr->GetNumberOfUndoItems(&numitems);
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(numitems, i);
+
+    rv = mgr->GetNumberOfRedoItems(&numitems);
+    EXPECT_NS_SUCCEEDED(rv);
+    EXPECT_EQ(numitems, 0);
+  }
+
+  for (i = 1; i <= 10; i++) {
+    rv = mgr->UndoTransaction();
+    EXPECT_NS_SUCCEEDED(rv);
+  }
+  rv = mgr->GetNumberOfUndoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  rv = mgr->GetNumberOfRedoItems(&numitems);
+  EXPECT_NS_SUCCEEDED(rv);
+  EXPECT_EQ(numitems, 10);
+
+  rv = mgr->Clear();
+  EXPECT_NS_SUCCEEDED(rv);
+}
+
+TEST(TestTXMgr, SimpleBatchTest)
+{
+  /*******************************************************************
+   *
+   * Initialize globals for test.
+   *
+   *******************************************************************/
+  reset_globals();
+  sDoOrderArr = sSimpleBatchTestDoOrderArr;
+  sUndoOrderArr = sSimpleBatchTestUndoOrderArr;
+  sRedoOrderArr = sSimpleBatchTestRedoOrderArr;
+
+  /*******************************************************************
+   *
+   * Run the quick batch test.
+   *
+   *******************************************************************/
+
+  SimpleTransactionFactory factory;
+  quick_batch_test(&factory);
+}
+
+TEST(TestTXMgr, AggregationBatchTest)
+{
+  /*******************************************************************
+   *
+   * Initialize globals for test.
+   *
+   *******************************************************************/
+
+  reset_globals();
+  sDoOrderArr = sAggregateBatchTestDoOrderArr;
+  sUndoOrderArr = sAggregateBatchTestUndoOrderArr;
+  sRedoOrderArr = sAggregateBatchTestRedoOrderArr;
+
+  /*******************************************************************
+   *
+   * Run the quick batch test.
+   *
+   *******************************************************************/
+
+  AggregateTransactionFactory factory(3, 2, BATCH_FLAG);
+
+  quick_batch_test(&factory);
+}
+
+/**
+ * Create 'iterations * (iterations + 1) / 2' transactions;
+ * do/undo/redo/undo them.
+ **/
+MOZ_CAN_RUN_SCRIPT_BOUNDARY void stress_test(TestTransactionFactory* factory,
+                                             int32_t iterations) {
+  /*******************************************************************
+   *
+   * Create a transaction manager:
+   *
+   *******************************************************************/
+
+  nsCOMPtr<nsITransactionManager> mgr = new TransactionManager();
+
+  nsresult rv;
+  int32_t i, j;
+
+  for (i = 1; i <= iterations; i++) {
+    /*******************************************************************
+     *
+     * Create and execute a bunch of transactions:
+     *
+     *******************************************************************/
+
+    for (j = 1; j <= i; j++) {
+      RefPtr<TestTransaction> tximpl = factory->create(mgr, NONE_FLAG);
+      rv = mgr->DoTransaction(tximpl);
+      EXPECT_NS_SUCCEEDED(rv);
+    }
+
+    /*******************************************************************
+     *
+     * Undo all the transactions:
+     *
+     *******************************************************************/
+
+    for (j = 1; j <= i; j++) {
+      rv = mgr->UndoTransaction();
+      EXPECT_NS_SUCCEEDED(rv);
+    }
+
+    /*******************************************************************
+     *
+     * Redo all the transactions:
+     *
+     *******************************************************************/
+
+    for (j = 1; j <= i; j++) {
+      rv = mgr->RedoTransaction();
+      EXPECT_NS_SUCCEEDED(rv);
+    }
+
+    /*******************************************************************
+     *
+     * Undo all the transactions again so that they all end up on
+     * the redo stack for pruning the next time we execute a new
+     * transaction
+     *
+     *******************************************************************/
+
+    for (j = 1; j <= i; j++) {
+      rv = mgr->UndoTransaction();
+      EXPECT_NS_SUCCEEDED(rv);
+    }
+  }
+
+  rv = mgr->Clear();
+  EXPECT_NS_SUCCEEDED(rv);
+}
+
+TEST(TestTXMgr, SimpleStressTest)
+{
+  /*******************************************************************
+   *
+   * Initialize globals for test.
+   *
+   *******************************************************************/
+
+  reset_globals();
+
+  /*******************************************************************
+   *
+   * Do the stress test:
+   *
+   *******************************************************************/
+
+  SimpleTransactionFactory factory;
+
+  int32_t iterations =
+#ifdef DEBUG
+      10
+#else
+      //
+      // 1500 iterations sends 1,125,750 transactions through the system!!
+      //
+      1500
+#endif
+      ;
+  stress_test(&factory, iterations);
+}
+
+TEST(TestTXMgr, AggregationStressTest)
+{
+  /*******************************************************************
+   *
+   * Initialize globals for test.
+   *
+   *******************************************************************/
+
+  reset_globals();
+
+  /*******************************************************************
+   *
+   * Do the stress test:
+   *
+   *******************************************************************/
+
+  AggregateTransactionFactory factory(3, 4);
+
+  int32_t iterations =
+#ifdef DEBUG
+      10
+#else
+      //
+      // 500 iterations sends 2,630,250 transactions through the system!!
+      //
+      500
+#endif
+      ;
+  stress_test(&factory, iterations);
+}
+
+TEST(TestTXMgr, AggregationBatchStressTest)
+{
+  /*******************************************************************
+   *
+   * Initialize globals for test.
+   *
+   *******************************************************************/
+
+  reset_globals();
+
+  /*******************************************************************
+   *
+   * Do the stress test:
+   *
+   *******************************************************************/
+
+  AggregateTransactionFactory factory(3, 4, BATCH_FLAG);
+
+  int32_t iterations =
+#ifdef DEBUG
+      10
+#else
+#  if defined(MOZ_ASAN) || defined(MOZ_WIDGET_ANDROID)
+      // See Bug 929985: 500 is too many for ASAN and Android, 100 is safe.
+      100
+#  else
+      //
+      // 500 iterations sends 2,630,250 transactions through the system!!
+      //
+      500
+#  endif
+#endif
+      ;
+  stress_test(&factory, iterations);
+}
diff --git a/editor/txmgr/tests/crashtests/407072-1.html b/editor/txmgr/tests/crashtests/407072-1.html
new file mode 100644
index 0000000000..e3aa3c216a
--- /dev/null
+++ b/editor/txmgr/tests/crashtests/407072-1.html
@@ -0,0 +1,22 @@
+<html>
+<head>
+<script>
+
+function boom()
+{
+  var br = document.getElementById("br");
+  br.contentEditable = "true";
+  br.focus();
+
+  try { document.execCommand("justifyfull", false, null);  } catch(e) { }
+  try { document.execCommand("justifyfull", false, null);  } catch(e) { }
+        document.execCommand("underline",   false, null);
+        document.execCommand("insertimage", false, "foo");
+  try { document.execCommand("outdent",     false, null);  } catch(e) { }
+}
+
+</script>
+</head>
+
+<body onload="boom();"><br id="br"></body>
+</html>
diff --git a/editor/txmgr/tests/crashtests/449006-1.html b/editor/txmgr/tests/crashtests/449006-1.html
new file mode 100644
index 0000000000..723792a239
--- /dev/null
+++ b/editor/txmgr/tests/crashtests/449006-1.html
@@ -0,0 +1,28 @@
+<html>
+<head>
+<script type="text/javascript">
+
+function boom()
+{
+  document.getElementById("d").focus();
+  document.execCommand("inserthtml", false, "AB");
+  document.execCommand("delete", false, null);
+  document.execCommand("undo", false, null);
+
+  document.addEventListener("DOMCharacterDataModified", f);
+  document.execCommand("redo", false, null);
+  document.removeEventListener("DOMCharacterDataModified", f);
+
+  function f()
+  {
+    document.removeEventListener("DOMCharacterDataModified", f);
+    document.execCommand("formatBlock", false, "<h3>");
+  }
+}
+
+</script>
+</head>
+
+<body onload="boom();"><div id="d" contenteditable="true"></div></body>
+
+</html>
diff --git a/editor/txmgr/tests/crashtests/crashtests.list b/editor/txmgr/tests/crashtests/crashtests.list
new file mode 100644
index 0000000000..d391875925
--- /dev/null
+++ b/editor/txmgr/tests/crashtests/crashtests.list
@@ -0,0 +1,2 @@
+needs-focus load 407072-1.html
+load 449006-1.html
diff --git a/editor/txmgr/tests/moz.build b/editor/txmgr/tests/moz.build
new file mode 100644
index 0000000000..9a8985dbc4
--- /dev/null
+++ b/editor/txmgr/tests/moz.build
@@ -0,0 +1,10 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+SOURCES += [
+    "TestTXMgr.cpp",
+]
+FINAL_LIBRARY = "xul-gtest"