--- a/media/mtransport/third_party/moz.build
+++ b/media/mtransport/third_party/moz.build
@@ -45,20 +45,16 @@ nICEr_non_unified_sources = [
     'nICEr/src/stun/stun_proc.c',
     'nICEr/src/stun/stun_server_ctx.c',
     'nICEr/src/stun/stun_util.c',
     'nICEr/src/stun/turn_client_ctx.c',
     'nICEr/src/util/cb_args.c',
     'nICEr/src/util/ice_util.c',
 ]
 
-# This file cannot be built in unified mode because it breaks Linux ASAN builds
-nICEr_non_unified_sources += [
-    'nICEr/src/util/mbslen.c',
-]
 nrappkit_non_unified_sources = [
     'nrappkit/src/log/r_log.c',
     'nrappkit/src/util/byteorder.c',
     'nrappkit/src/util/hex.c',
     'nrappkit/src/util/libekr/debug.c',
     'nrappkit/src/util/libekr/r_assoc.c',
     'nrappkit/src/util/libekr/r_crc32.c',
     'nrappkit/src/util/libekr/r_data.c',

--- a/media/mtransport/third_party/nICEr/IMPORT_FILES
+++ b/media/mtransport/third_party/nICEr/IMPORT_FILES
@@ -62,10 +62,8 @@
                 ./src/stun/turn_client_ctx.c
                 ./src/stun/turn_client_ctx.h
 
                 # Util
                 ./src/util/cb_args.c
                 ./src/util/cb_args.h
                 ./src/util/ice_util.c
                 ./src/util/ice_util.h
-                ./src/util/mbslen.c
-                ./src/util/mbslen.h

--- a/media/mtransport/third_party/nICEr/nicer.gyp
+++ b/media/mtransport/third_party/nICEr/nicer.gyp
@@ -114,18 +114,16 @@
                 "./src/stun/turn_client_ctx.c",
                 "./src/stun/turn_client_ctx.h",
 
                 # Util
                 "./src/util/cb_args.c",
                 "./src/util/cb_args.h",
                 "./src/util/ice_util.c",
                 "./src/util/ice_util.h",
-                "./src/util/mbslen.c",
-                "./src/util/mbslen.h",
 
 
           ],
 
           'defines' : [
               'SANITY_CHECKS',
               'USE_TURN',
               'USE_ICE',

deleted file mode 100644
--- a/media/mtransport/third_party/nICEr/src/util/mbslen.c
+++ /dev/null
@@ -1,139 +0,0 @@
-/*
-Copyright (c) 2007, Adobe Systems, Incorporated
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are
-met:
-
-* Redistributions of source code must retain the above copyright
-  notice, this list of conditions and the following disclaimer.
-
-* Redistributions in binary form must reproduce the above copyright
-  notice, this list of conditions and the following disclaimer in the
-  documentation and/or other materials provided with the distribution.
-
-* Neither the name of Adobe Systems, Network Resonance nor the names of its
-  contributors may be used to endorse or promote products derived from
-  this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-*/
-
-
-#ifdef LINUX
-#define _GNU_SOURCE 1
-#endif
-#include <string.h>
-
-#include <errno.h>
-#include <csi_platform.h>
-
-#include <assert.h>
-#include <locale.h>
-#include <stdlib.h>
-#include <wchar.h>
-#if defined(DARWIN) || defined(__DragonFly__) || defined(__FreeBSD__)
-#define HAVE_XLOCALE
-#endif
-
-#ifdef HAVE_XLOCALE
-#include <xlocale.h>
-#endif /* HAVE_XLOCALE */
-
-#include "nr_api.h"
-#include "mbslen.h"
-
-/* get number of characters in a mult-byte character string */
-int
-mbslen(const char *s, size_t *ncharsp)
-{
-#ifdef HAVE_XLOCALE
-    static locale_t loc = 0;
-    static int initialized = 0;
-#endif /* HAVE_XLOCALE */
-#ifdef WIN32
-    char *my_locale=0;
-    unsigned int i;
-#endif  /* WIN32 */
-    int _status;
-    size_t nbytes;
-    int nchars;
-    mbstate_t mbs;
-
-#ifdef HAVE_XLOCALE
-    if (! initialized) {
-        initialized = 1;
-        loc = newlocale(LC_CTYPE_MASK, "UTF-8", LC_GLOBAL_LOCALE);
-    }
-
-    if (loc == 0) {
-        /* unable to create the UTF-8 locale */
-        assert(loc != 0);  /* should never happen */
-#endif /* HAVE_XLOCALE */
-
-#ifdef WIN32
-    if (!setlocale(LC_CTYPE, 0))
-        ABORT(R_INTERNAL);
-
-    if (!(my_locale = r_strdup(setlocale(LC_CTYPE, 0))))
-        ABORT(R_NO_MEMORY);
-
-    for (i=0; i<strlen(my_locale); i++)
-        my_locale[i] = toupper(my_locale[i]);
-
-    if (!strstr(my_locale, "UTF-8") && !strstr(my_locale, "UTF8"))
-        ABORT(R_NOT_FOUND);
-#else
-    /* can't count UTF-8 characters with mbrlen if the locale isn't UTF-8 */
-    /* null-checking setlocale is required because Android */
-    char *locale = setlocale(LC_CTYPE, 0);
-    /* some systems use "utf8" instead of "UTF-8" like Fedora 17 */
-    if (!locale || (!strcasestr(locale, "UTF-8") && !strcasestr(locale, "UTF8")))
-        ABORT(R_NOT_FOUND);
-#endif
-
-#ifdef HAVE_XLOCALE
-    }
-#endif /* HAVE_XLOCALE */
-
-    memset(&mbs, 0, sizeof(mbs));
-    nchars = 0;
-
-#ifdef HAVE_XLOCALE
-    while (*s != '\0' && (nbytes = mbrlen_l(s, strlen(s), &mbs, loc)) != 0)
-#else
-    while (*s != '\0' && (nbytes = mbrlen(s, strlen(s), &mbs)) != 0)
-#endif /* HAVE_XLOCALE */
-    {
-        if (nbytes == (size_t)-1)   /* should never happen */ {
-            ABORT(R_INTERNAL);
-        }
-        if (nbytes == (size_t)-2)   /* encoding error */ {
-            ABORT(R_BAD_DATA);
-        }
-
-        s += nbytes;
-        ++nchars;
-    }
-
-    *ncharsp = nchars;
-
-    _status = 0;
-  abort:
-#ifdef WIN32
-    RFREE(my_locale);
-#endif
-    return _status;
-}
-

deleted file mode 100644
--- a/media/mtransport/third_party/nICEr/src/util/mbslen.h
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
-Copyright (c) 2007, Adobe Systems, Incorporated
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are
-met:
-
-* Redistributions of source code must retain the above copyright
-  notice, this list of conditions and the following disclaimer.
-
-* Redistributions in binary form must reproduce the above copyright
-  notice, this list of conditions and the following disclaimer in the
-  documentation and/or other materials provided with the distribution.
-
-* Neither the name of Adobe Systems, Network Resonance nor the names of its
-  contributors may be used to endorse or promote products derived from
-  this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-*/
-
-
-
-#ifndef _mbslen_h
-#define _mbslen_h
-
-/* get number of characters in a mult-byte character string */
-int mbslen(const char *s, size_t *ncharsp);
-
-#endif
-