GN: Fix windows clang errors. Attempt 2.

webrtc/test/BUILD.gn

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("//build/config/ui.gni")
 import("//testing/test.gni")
@@ skipping 15 matching lines @@
     ":test_support_unittests",
     ":video_test_common",
   ]
 }
 
 config("channel_transport_warnings_config") {
   if (is_win) {
     cflags = [ "/wd4302" ]  # cast truncation
 
     if (is_clang) {
-      # GN orders flags on a target before flags from configs. The default config
-      # adds -Wall, and this flag have to be after -Wall -- so they need to
-      # come from a config and cannot be on the target directly.
+      # GN orders flags on a target before flags from configs. The default
+      # config adds -Wall, and this flag have to be after -Wall -- so they need
+      # to come from a config and cannot be on the target directly.
       cflags += [
         "-Wno-parentheses-equality",
         "-Wno-reorder",
         "-Wno-tautological-constant-out-of-range-compare",
+
+        # See https://bugs.chromium.org/p/webrtc/issues/detail?id=6268
+        # for -Wno-thread-safety-analysis
+        "-Wno-thread-safety-analysis",
         "-Wno-unused-private-field",
       ]
     }
   }
 }
 
 source_set("channel_transport") {
   testonly = true
   sources = [
     "channel_transport/channel_transport.cc",
@@ skipping 429 matching lines @@
     configs -= [ "//build/config/clang:find_bad_constructs" ]
   }
 
   deps = [
     ":test_support",
     ":video_test_common",
     "../modules/media_file",
     "//testing/gtest",
   ]
 }