Update from https://crrev.com/306655

net/third_party/nss/ssl.gyp

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'conditions': [
     [ 'os_posix == 1 and OS != "mac" and OS != "ios"', {
       'conditions': [
         ['sysroot!=""', {
           'variables': {
@@ skipping 61 matching lines @@
       'sources!': [
         'ssl/os2_err.c',
         'ssl/os2_err.h',
       ],
       'defines': [
         'NO_PKCS11_BYPASS',
         'NSS_ENABLE_ECC',
         'USE_UTIL_DIRECTLY',
       ],
       'msvs_disabled_warnings': [4018, 4244, 4267],
+      'variables': {
+        'clang_warning_flags_unset': [
+          # ssl uses PR_ASSERT(!"foo") instead of PR_ASSERT(false && "foo")
+          '-Wstring-conversion',
+        ],
+      },
       'conditions': [
         ['component == "shared_library"', {
           'conditions': [
             ['OS == "mac" or OS == "ios"', {
               'xcode_settings': {
                 'GCC_SYMBOLS_PRIVATE_EXTERN': 'NO',
               },
             }],
             ['OS == "win"', {
               'sources': [
@@ skipping 94 matching lines @@
       'configurations': {
         'Debug_Base': {
           'defines': [
             'DEBUG',
           ],
         },
       },
     },
   ],
 }