GN: Tighten up test target visibility + refactorings

webrtc/test/fuzzers/BUILD.gn

 # Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("../../webrtc.gni")
 import("//build/config/features.gni")
@@ skipping 100 matching lines @@
   ]
 }
 
 webrtc_fuzzer_test("ulpfec_generator_fuzzer") {
   sources = [
     "ulpfec_generator_fuzzer.cc",
   ]
   deps = [
     "../../base:rtc_base_approved",
     "../../modules/rtp_rtcp",
-    "../../modules/rtp_rtcp:rtp_rtcp_unittests",
+    "../../modules/rtp_rtcp:fec_test_helper",
   ]
 }
 
 webrtc_fuzzer_test("flexfec_receiver_fuzzer") {
   sources = [
     "flexfec_receiver_fuzzer.cc",
   ]
   deps = [
     "../../base:rtc_base_approved",
     "../../modules/rtp_rtcp",
@@ skipping 197 matching lines @@
 webrtc_fuzzer_test("transport_feedback_packet_loss_tracker_fuzzer") {
   sources = [
     "transport_feedback_packet_loss_tracker_fuzzer.cc",
   ]
   deps = [
     "../../base:rtc_base_approved",
     "../../modules/rtp_rtcp",
     "../../voice_engine",
   ]
 }