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

media/BUILD.gn

 # Copyright 2014 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/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/features.gni")
 import("//build/config/linux/pkg_config.gni")
 import("//build/config/ui.gni")
@@ skipping 800 matching lines @@
 }
 
 fuzzer_test("media_vp8_parser_fuzzer") {
   sources = [
     "filters/vp8_parser_fuzzertest.cc",
   ]
   deps = [
     ":media",
     "//base",
   ]
-  libfuzzer_options = "filters/vp8_parser_fuzzertest.options"
+  libfuzzer_options = [ "max_len = 400000" ]
   dict = "test/vp8.dict"
 }
 
 fuzzer_test("media_vp9_parser_fuzzer") {
   sources = [
     "filters/vp9_parser_fuzzertest.cc",
   ]
   deps = [
     ":media",
     "//base",
   ]
-  libfuzzer_options = "filters/vp9_parser_fuzzertest.options"
+  libfuzzer_options = [ "max_len = 400000" ]
 }