GN: Refactor webrtc_nonparallel_tests and audio_tests to avoid crossing package boundaries.

webrtc/audio/utility/BUILD.gn

Index: webrtc/audio/utility/BUILD.gn
diff --git a/webrtc/audio/utility/BUILD.gn b/webrtc/audio/utility/BUILD.gn
index d85b30d1c028f55f5c7e8450b57e1331f7d07283..668c95ea4396f4807cd90a16aee2c33ace4c76e8 100644
--- a/webrtc/audio/utility/BUILD.gn
+++ b/webrtc/audio/utility/BUILD.gn
@@ -25,3 +25,20 @@ rtc_static_library("audio_frame_operations") {
     "../../modules/audio_coding:audio_format_conversion",
   ]
 }
+
+if (rtc_include_tests) {
+  rtc_source_set("utility_tests") {
+    testonly = true
+    sources = [
+      "audio_frame_operations_unittest.cc",
+    ]
+    deps = [
+      ":audio_frame_operations",
+      "//testing/gtest",
+    ]
+    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" ]
+    }
+  }
+}