[libfuzzer] store custom options in .GN build target instead of a separate file.

net/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/buildflag_header.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
@@ skipping 1901 matching lines @@
 fuzzer_test("net_unescape_url_component_fuzzer") {
   sources = [
     "base/unescape_url_component_fuzzer.cc",
   ]
   deps = [
     ":net_fuzzer_test_support",
     "//base",
     "//net",
   ]
   dict = "base/unescape_url_component_fuzzer.dict"
-  libfuzzer_options = "base/unescape_url_component_fuzzer.options"
+  libfuzzer_options = [ "max_len = 2048" ]
 }
 
 fuzzer_test("net_websocket_frame_parser_fuzzer") {
   sources = [
     "websockets/websocket_frame_parser_fuzzer.cc",
   ]
   deps = [
     ":net_fuzzer_test_support",
     "//net",
   ]
@@ skipping 13 matching lines @@
 fuzzer_test("net_quic_crypto_framer_parse_message_fuzzer") {
   sources = [
     "quic/quic_crypto_framer_parse_message_fuzzer.cc",
   ]
   deps = [
     ":net_fuzzer_test_support",
     "//base",
     "//net",
   ]
 }