GN: Exclude suppressions of Chromium Clang warnings for Chromium builds.

webrtc/modules/audio_conference_mixer/BUILD.gn

Index: webrtc/modules/audio_conference_mixer/BUILD.gn
diff --git a/webrtc/modules/audio_conference_mixer/BUILD.gn b/webrtc/modules/audio_conference_mixer/BUILD.gn
index 129ff5b5ec86d69aaa4746efb275e9b74d205c09..58228b5a83a81512b96c7e9540689c6d115b3a2a 100644
--- a/webrtc/modules/audio_conference_mixer/BUILD.gn
+++ b/webrtc/modules/audio_conference_mixer/BUILD.gn
@@ -33,9 +33,8 @@ rtc_static_library("audio_conference_mixer") {
 
   public_configs = [ ":audio_conference_mixer_config" ]
 
-  if (is_clang) {
-    # Suppress warnings from Chrome's Clang plugins.
-    # See http://code.google.com/p/webrtc/issues/detail?id=163 for details.
+  if (!build_with_chromium && is_clang) {
+    # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
     suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
   }