Replace remaining gflags usages with rtc_base/flags

webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc

Index: webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc
diff --git a/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc b/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc
index 3ac68d4435cdfc322a6116fd0a1ed91785d27330..11b172ab28f6f322592955e97acaa9f2c774fa70 100644
--- a/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc
+++ b/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc
@@ -10,12 +10,12 @@
 
 #include <vector>
 
-#include "gflags/gflags.h"
 #include "webrtc/common_audio/channel_buffer.h"
 #include "webrtc/common_audio/wav_file.h"
 #include "webrtc/modules/audio_processing/beamformer/nonlinear_beamformer.h"
 #include "webrtc/modules/audio_processing/test/test_utils.h"
 #include "webrtc/rtc_base/checks.h"
+#include "webrtc/rtc_base/flags.h"
 #include "webrtc/rtc_base/format_macros.h"
 
 DEFINE_string(i, "", "The name of the input file to read from.");
@@ -24,6 +24,7 @@ DEFINE_string(mic_positions, "",
     "Space delimited cartesian coordinates of microphones in meters. "
     "The coordinates of each point are contiguous. "
     "For a two element array: \"x1 y1 z1 x2 y2 z2\"");
+DEFINE_bool(help, false, "Prints this message.");
 
 namespace webrtc {
 namespace {
@@ -34,29 +35,36 @@ const int kChunkSizeMs = 1000 / kChunksPerSecond;
 const char kUsage[] =
     "Command-line tool to run beamforming on WAV files. The signal is passed\n"
     "in as a single band, unlike the audio processing interface which splits\n"
-    "signals into multiple bands.";
+    "signals into multiple bands.\n";
 
 }  // namespace
 
 int main(int argc, char* argv[]) {
-  google::SetUsageMessage(kUsage);
-  google::ParseCommandLineFlags(&argc, &argv, true);
+  if (rtc::FlagList::SetFlagsFromCommandLine(&argc, argv, true) ||
+      FLAG_help || argc != 1) {
+    printf("%s", kUsage);
+    if (FLAG_help) {
+      rtc::FlagList::Print(nullptr, false);
+      return 0;
+    }
+    return 1;
+  }
 
-  WavReader in_file(FLAGS_i);
-  WavWriter out_file(FLAGS_o, in_file.sample_rate(), in_file.num_channels());
+  WavReader in_file(FLAG_i);
+  WavWriter out_file(FLAG_o, in_file.sample_rate(), in_file.num_channels());
 
   const size_t num_mics = in_file.num_channels();
   const std::vector<Point> array_geometry =
-      ParseArrayGeometry(FLAGS_mic_positions, num_mics);
+      ParseArrayGeometry(FLAG_mic_positions, num_mics);
   RTC_CHECK_EQ(array_geometry.size(), num_mics);
 
   NonlinearBeamformer bf(array_geometry, array_geometry.size());
   bf.Initialize(kChunkSizeMs, in_file.sample_rate());
 
   printf("Input file: %s\nChannels: %" PRIuS ", Sample rate: %d Hz\n\n",
-         FLAGS_i.c_str(), in_file.num_channels(), in_file.sample_rate());
+         FLAG_i, in_file.num_channels(), in_file.sample_rate());
   printf("Output file: %s\nChannels: %" PRIuS ", Sample rate: %d Hz\n\n",
-         FLAGS_o.c_str(), out_file.num_channels(), out_file.sample_rate());
+         FLAG_o, out_file.num_channels(), out_file.sample_rate());
 
   ChannelBuffer<float> buf(
       rtc::CheckedDivExact(in_file.sample_rate(), kChunksPerSecond),