diff --git a/mozilla/base/src/nsStringImpl.cpp b/mozilla/base/src/nsStringImpl.cpp
new file mode 100644
index 00000000000..fe67bc0153c
--- /dev/null
+++ b/mozilla/base/src/nsStringImpl.cpp
@@ -0,0 +1,137 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/*
+ * The contents of this file are subject to the Netscape Public License
+ * Version 1.0 (the "NPL"); you may not use this file except in
+ * compliance with the NPL.  You may obtain a copy of the NPL at
+ * http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the NPL is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
+ * for the specific language governing rights and limitations under the
+ * NPL.
+ *
+ * The Initial Developer of this code under the NPL is Netscape
+ * Communications Corporation.  Portions created by Netscape are
+ * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
+ * Reserved.
+ */
+
+/*
+
+  The default implementation for nsIString.
+
+ */
+
+
+#include "nsIString.h"
+#include "nsStr.h"
+
+////////////////////////////////////////////////////////////////////////
+
+static NS_DEFINE_IID(kIStringIID, NS_ISTRING_IID);
+
+////////////////////////////////////////////////////////////////////////
+
+class nsStringImpl : public nsIString
+{
+protected:
+  nsStr mStr;
+
+public:
+  nsStringImpl();
+  virtual ~nsStringImpl();
+
+  // nsISupports interface
+  NS_DECL_ISUPPORTS
+
+  // nsIString interface
+  NS_IMETHOD Init(eCharSize aCharSize);
+  NS_IMETHOD SetStr(nsStr* aStr);
+  NS_IMETHOD GetStr(nsStr* aStr);
+  NS_IMETHOD GetImmutableStr(const nsStr** aStr);
+};
+
+
+////////////////////////////////////////////////////////////////////////
+
+nsStringImpl::nsStringImpl()
+{
+  NS_INIT_REFCNT();
+  nsStr::Initialize(mStr, kDefaultCharSize);
+}
+
+
+nsStringImpl::~nsStringImpl()
+{
+  nsStr::Destroy(mStr);
+}
+
+PR_IMPLEMENT(nsresult)
+NS_NewString(nsIString** aString)
+{
+  NS_PRECONDITION(aString != nsnull, "null ptr");
+  if (! aString)
+    return NS_ERROR_NULL_POINTER;
+
+  nsStringImpl* s = new nsStringImpl();
+  if (! s)
+    return NS_ERROR_OUT_OF_MEMORY;
+
+  NS_ADDREF(s);
+  *aString = s;
+  return NS_OK;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+// nsISupports interface
+
+NS_IMPL_ADDREF(nsStringImpl);
+NS_IMPL_RELEASE(nsStringImpl);
+NS_IMPL_QUERY_INTERFACE(nsStringImpl, kIStringIID);
+
+////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+nsStringImpl::Init(eCharSize aCharSize)
+{
+  nsStr::Initialize(mStr, aCharSize);
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsStringImpl::SetStr(nsStr* aStr)
+{
+  NS_PRECONDITION(aStr != nsnull, "null ptr");
+  if (! aStr)
+    return NS_ERROR_NULL_POINTER;
+
+  nsStr::Assign(mStr, *aStr, 0, aStr->mLength);
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsStringImpl::GetStr(nsStr* aStr)
+{
+  NS_PRECONDITION(aStr != nsnull, "null ptr");
+  if (! aStr)
+    return NS_ERROR_NULL_POINTER;
+
+  nsStr::Assign(*aStr, mStr, 0, mStr.mLength);
+  return NS_OK;
+}
+
+
+
+NS_IMETHODIMP
+nsStringImpl::GetImmutableStr(const nsStr** aImmutableStr)
+{
+  NS_PRECONDITION(aImmutableStr != nsnull, "null ptr");
+  if (! aImmutableStr)
+    return NS_ERROR_NULL_POINTER;
+
+  *aImmutableStr = &mStr;
+  return NS_OK;
+}
diff --git a/mozilla/xpcom/ds/nsStringImpl.cpp b/mozilla/xpcom/ds/nsStringImpl.cpp
new file mode 100644
index 00000000000..fe67bc0153c
--- /dev/null
+++ b/mozilla/xpcom/ds/nsStringImpl.cpp
@@ -0,0 +1,137 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/*
+ * The contents of this file are subject to the Netscape Public License
+ * Version 1.0 (the "NPL"); you may not use this file except in
+ * compliance with the NPL.  You may obtain a copy of the NPL at
+ * http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the NPL is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
+ * for the specific language governing rights and limitations under the
+ * NPL.
+ *
+ * The Initial Developer of this code under the NPL is Netscape
+ * Communications Corporation.  Portions created by Netscape are
+ * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
+ * Reserved.
+ */
+
+/*
+
+  The default implementation for nsIString.
+
+ */
+
+
+#include "nsIString.h"
+#include "nsStr.h"
+
+////////////////////////////////////////////////////////////////////////
+
+static NS_DEFINE_IID(kIStringIID, NS_ISTRING_IID);
+
+////////////////////////////////////////////////////////////////////////
+
+class nsStringImpl : public nsIString
+{
+protected:
+  nsStr mStr;
+
+public:
+  nsStringImpl();
+  virtual ~nsStringImpl();
+
+  // nsISupports interface
+  NS_DECL_ISUPPORTS
+
+  // nsIString interface
+  NS_IMETHOD Init(eCharSize aCharSize);
+  NS_IMETHOD SetStr(nsStr* aStr);
+  NS_IMETHOD GetStr(nsStr* aStr);
+  NS_IMETHOD GetImmutableStr(const nsStr** aStr);
+};
+
+
+////////////////////////////////////////////////////////////////////////
+
+nsStringImpl::nsStringImpl()
+{
+  NS_INIT_REFCNT();
+  nsStr::Initialize(mStr, kDefaultCharSize);
+}
+
+
+nsStringImpl::~nsStringImpl()
+{
+  nsStr::Destroy(mStr);
+}
+
+PR_IMPLEMENT(nsresult)
+NS_NewString(nsIString** aString)
+{
+  NS_PRECONDITION(aString != nsnull, "null ptr");
+  if (! aString)
+    return NS_ERROR_NULL_POINTER;
+
+  nsStringImpl* s = new nsStringImpl();
+  if (! s)
+    return NS_ERROR_OUT_OF_MEMORY;
+
+  NS_ADDREF(s);
+  *aString = s;
+  return NS_OK;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+// nsISupports interface
+
+NS_IMPL_ADDREF(nsStringImpl);
+NS_IMPL_RELEASE(nsStringImpl);
+NS_IMPL_QUERY_INTERFACE(nsStringImpl, kIStringIID);
+
+////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+nsStringImpl::Init(eCharSize aCharSize)
+{
+  nsStr::Initialize(mStr, aCharSize);
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsStringImpl::SetStr(nsStr* aStr)
+{
+  NS_PRECONDITION(aStr != nsnull, "null ptr");
+  if (! aStr)
+    return NS_ERROR_NULL_POINTER;
+
+  nsStr::Assign(mStr, *aStr, 0, aStr->mLength);
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsStringImpl::GetStr(nsStr* aStr)
+{
+  NS_PRECONDITION(aStr != nsnull, "null ptr");
+  if (! aStr)
+    return NS_ERROR_NULL_POINTER;
+
+  nsStr::Assign(*aStr, mStr, 0, mStr.mLength);
+  return NS_OK;
+}
+
+
+
+NS_IMETHODIMP
+nsStringImpl::GetImmutableStr(const nsStr** aImmutableStr)
+{
+  NS_PRECONDITION(aImmutableStr != nsnull, "null ptr");
+  if (! aImmutableStr)
+    return NS_ERROR_NULL_POINTER;
+
+  *aImmutableStr = &mStr;
+  return NS_OK;
+}