Tracking rbe tools with a GN target

Files under the tools directory were untracked by GN.

This cl creates a target for them. The target is testonly because it
depends on "webrtc/test:rtp_test_utils".

BUG=webrtc:7651
NOTRY=True

Review-Url: https://codereview.webrtc.org/2886713002
Cr-Original-Commit-Position: refs/heads/master@{#19683}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 2877eaf7fe2759b5464596ceca4e8f640f809a16
diff --git a/modules/remote_bitrate_estimator/BUILD.gn b/modules/remote_bitrate_estimator/BUILD.gn
index f13e8fc..8bcbe7b 100644
--- a/modules/remote_bitrate_estimator/BUILD.gn
+++ b/modules/remote_bitrate_estimator/BUILD.gn
@@ -57,6 +57,26 @@
   ]
 }
 
+if (!build_with_chromium) {
+  rtc_source_set("bwe_rtp") {
+    testonly = true
+    sources = [
+      "tools/bwe_rtp.cc",
+      "tools/bwe_rtp.h",
+    ]
+    deps = [
+      ":remote_bitrate_estimator",
+      "../../rtc_base:rtc_base_approved",
+      "../../test:rtp_test_utils",
+      "../rtp_rtcp:rtp_rtcp",
+    ]
+    if (is_clang) {
+      # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
+      suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
+    }
+  }
+}
+
 if (rtc_include_tests) {
   rtc_static_library("bwe_simulator_lib") {
     testonly = true
diff --git a/modules/remote_bitrate_estimator/tools/bwe_rtp.cc b/modules/remote_bitrate_estimator/tools/bwe_rtp.cc
index de0d5ea..d849398 100644
--- a/modules/remote_bitrate_estimator/tools/bwe_rtp.cc
+++ b/modules/remote_bitrate_estimator/tools/bwe_rtp.cc
@@ -79,7 +79,7 @@
   if (rtc::FlagList::SetFlagsFromCommandLine(&argc, argv, true)) {
     return 1;
   }
-  if (FLAG_help) {
+  if (flags::FLAG_help) {
     rtc::FlagList::Print(nullptr, false);
     return 0;
   }