Replace remaining gflags usages with rtc_base/flags

webrtc/modules/audio_processing/test/conversational_speech/generator.cc

Index: webrtc/modules/audio_processing/test/conversational_speech/generator.cc
diff --git a/webrtc/modules/audio_processing/test/conversational_speech/generator.cc b/webrtc/modules/audio_processing/test/conversational_speech/generator.cc
index c7f86dec1ea948be9e7e91386fa66c9f42e998c1..702c522bfcba87094e0883f74372a472b510abb6 100644
--- a/webrtc/modules/audio_processing/test/conversational_speech/generator.cc
+++ b/webrtc/modules/audio_processing/test/conversational_speech/generator.cc
@@ -10,12 +10,12 @@
 
 #include <iostream>
 
-#include "gflags/gflags.h"
 #include "webrtc/modules/audio_processing/test/conversational_speech/config.h"
 #include "webrtc/modules/audio_processing/test/conversational_speech/multiend_call.h"
 #include "webrtc/modules/audio_processing/test/conversational_speech/simulator.h"
 #include "webrtc/modules/audio_processing/test/conversational_speech/timing.h"
 #include "webrtc/modules/audio_processing/test/conversational_speech/wavreader_factory.h"
+#include "webrtc/rtc_base/flags.h"
 #include "webrtc/rtc_base/ptr_util.h"
 #include "webrtc/test/testsupport/fileutils.h"
 
@@ -23,14 +23,6 @@ namespace webrtc {
 namespace test {
 namespace {
 
-// Adapting DirExists/FileExists interfaces to DEFINE_validator.
-auto dir_exists = [](const char* c, const std::string& dirpath) {
-  return DirExists(dirpath);
-};
-auto file_exists = [](const char* c, const std::string& filepath) {
-  return FileExists(filepath);
-};
-
 const char kUsageDescription[] =
     "Usage: conversational_speech_generator\n"
     "          -i <path/to/source/audiotracks>\n"
@@ -38,21 +30,30 @@ const char kUsageDescription[] =
     "          -o <output/path>\n"
     "\n\n"
     "Command-line tool to generate multiple-end audio tracks to simulate "
-    "conversational speech with two or more participants.";
+    "conversational speech with two or more participants.\n";
 
 DEFINE_string(i, "", "Directory containing the speech turn wav files");
-DEFINE_validator(i, dir_exists);
 DEFINE_string(t, "", "Path to the timing text file");
-DEFINE_validator(t, file_exists);
 DEFINE_string(o, "", "Output wav files destination path");
-DEFINE_validator(o, dir_exists);
+DEFINE_bool(help, false, "Prints this message");
 
 }  // namespace
 
 int main(int argc, char* argv[]) {
-  google::SetUsageMessage(kUsageDescription);
-  google::ParseCommandLineFlags(&argc, &argv, true);
-  conversational_speech::Config config(FLAGS_i, FLAGS_t, FLAGS_o);
+  if (rtc::FlagList::SetFlagsFromCommandLine(&argc, argv, true) ||
+      FLAG_help || argc != 0) {
+    printf("%s", kUsageDescription);
+    if (FLAG_help) {
+      rtc::FlagList::Print(nullptr, false);
+      return 0;
+    }
+    return 1;
+  }
+  RTC_CHECK(DirExists(FLAG_i));

[hlundin-webrtc, 2017/08/30 21:07:54]

In these three lines, I think it would be helpful to << a better error message,
since I guess the default printout will be something like "check failed,
expected true, actual false". The user would probably need a reminder of what
flag value was tested.

[oprypin_webrtc, 2017/08/31 00:23:25]

I did make sure that there's always at least some hint to what's going wrong
with the flags. That's ensured by RTC_CHECK echoing its contents.
It actually looks like this:
  # Fatal error in
../../webrtc/modules/audio_processing/test/conversational_speech/generator.cc,
line 52
  # last system error: 2
  # Check failed: DirExists(FLAG_i)
vs previous:
  ERROR: failed validation of new value '...' for flag 'i'

So I think it's good.

[hlundin-webrtc, 2017/08/31 05:59:20]

OK. Fair enough.

+  RTC_CHECK(FileExists(FLAG_t));
+  RTC_CHECK(DirExists(FLAG_o));
+
+  conversational_speech::Config config(FLAG_i, FLAG_t, FLAG_o);
 
   // Load timing.
   std::vector<conversational_speech::Turn> timing =