Add webrtc_perf_tests to BUILD.gn

webrtc/modules/audio_processing/BUILD.gn

Index: webrtc/modules/audio_processing/BUILD.gn
diff --git a/webrtc/modules/audio_processing/BUILD.gn b/webrtc/modules/audio_processing/BUILD.gn
index 9c1674a102eabffbfd7485aad385573f78f9fa6b..7ef0a77f3b1ab07db7ffaec402213e2dba10c1b5 100644
--- a/webrtc/modules/audio_processing/BUILD.gn
+++ b/webrtc/modules/audio_processing/BUILD.gn
@@ -319,6 +319,8 @@ if (rtc_include_tests) {
   source_set("audioproc_test_utils") {
     testonly = true
     sources = [
+      "test/audio_buffer_tools.cc",

[phoglund_chromium, 2016/07/26 12:33:29]

Did you mean to make this change in this cl? If so, please update the CL
description.

[ehmaldonado_webrtc, 2016/07/26 12:44:07]

Yes, I meant to change it.
Done.

+      "test/audio_buffer_tools.h",
       "test/test_utils.cc",
       "test/test_utils.h",
     ]