Reland "Switch frame_analyzer to ABSL_FLAG."

This is a reland of 3668e9b56198eb8112562d017c47a52050be3561

Original change's description:
> Switch frame_analyzer to ABSL_FLAG.
>
> Bug: webrtc:10616
> Change-Id: I34473632431569406b9086f57caac12434862005
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/136801
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#28358}

TBR=kwiberg@webrtc.org

Bug: webrtc:10616
Change-Id: I661ec82938c80964382fcd0692cf9d5cdb132977
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/143681
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28361}
diff --git a/rtc_tools/BUILD.gn b/rtc_tools/BUILD.gn
index 2cd4991..e3b9eb1 100644
--- a/rtc_tools/BUILD.gn
+++ b/rtc_tools/BUILD.gn
@@ -125,18 +125,20 @@
 
 rtc_executable("frame_analyzer") {
   visibility = [ "*" ]
+  testonly = true
   sources = [
     "frame_analyzer/frame_analyzer.cc",
   ]
 
   deps = [
-    ":command_line_parser",
     ":video_file_reader",
     ":video_file_writer",
     ":video_quality_analysis",
     "../api:scoped_refptr",
     "../rtc_base:stringutils",
     "../test:perf_test",
+    "//third_party/abseil-cpp/absl/flags:flag",
+    "//third_party/abseil-cpp/absl/flags:parse",
     "//third_party/abseil-cpp/absl/strings",
   ]
 }