GN: Refactor modules_unittests to eliminate package boundary violations.

webrtc/modules/audio_conference_mixer/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/webrtc.gni")
 
@@ skipping 28 matching lines @@
   }
 
   deps = [
     "../..:webrtc_common",
     "../../audio/utility:audio_frame_operations",
     "../../base:rtc_base_approved",
     "../../system_wrappers",
     "../audio_processing",
   ]
 }
+
+if (rtc_include_tests) {
+  rtc_source_set("audio_conference_mixer_unittests") {
+    testonly = true
+    sources = [
+      "test/audio_conference_mixer_unittest.cc",
+    ]
+    deps = [
+      ":audio_conference_mixer",
+      "../../test:test_support",
+      "//testing/gmock",
+    ]
+    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" ]
+    }
+  }
+}