Migrate WebRTC test infra to ABSL_FLAG.

This is the last CL required to migrate WebRTC to ABSL_FLAG, rtc::Flag
will be removed soon after this one lands.

Bug: webrtc:10616
Change-Id: I2807cec39e28a2737d2c49e2dc23f2a6f98d08f0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/145727
Reviewed-by: Tommi <tommi@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28606}
diff --git a/audio/BUILD.gn b/audio/BUILD.gn
index 0e78a68..cf8af3d 100644
--- a/audio/BUILD.gn
+++ b/audio/BUILD.gn
@@ -190,7 +190,6 @@
         "../api:simulated_network_api",
         "../call:simulated_network",
         "../common_audio",
-        "../rtc_base:rtc_base_approved",
         "../system_wrappers",
         "../test:fileutils",
         "../test:perf_test",
@@ -199,7 +198,8 @@
         "../test:test_support",
         "../test/pc/e2e:network_quality_metrics_reporter",
         "//testing/gtest",
-        "//third_party/abseil-cpp/absl/memory:memory",
+        "//third_party/abseil-cpp/absl/flags:flag",
+        "//third_party/abseil-cpp/absl/memory",
       ]
       if (is_android) {
         deps += [ "//testing/android/native_test:native_test_native_code" ]