Add recursive pattern matching for subfolders in file_enumerator.

base/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.
 
 # HOW TO WRITE CONDITIONALS IN THIS FILE
 # ======================================
 #
 # In many other places, one would write a conditional that expresses all the
 # cases when a source file is used or unused, and then either add or subtract
 # it from the sources list in that case
@@ skipping 2014 matching lines @@
     "debug/proc_maps_linux_unittest.cc",
     "debug/stack_trace_unittest.cc",
     "debug/task_annotator_unittest.cc",
     "debug/thread_heap_usage_tracker_unittest.cc",
     "deferred_sequenced_task_runner_unittest.cc",
     "environment_unittest.cc",
     "feature_list_unittest.cc",
     "file_version_info_win_unittest.cc",
     "files/dir_reader_posix_unittest.cc",
     "files/file_descriptor_watcher_posix_unittest.cc",
+    "files/file_enumerator_unittest.cc",
     "files/file_locking_unittest.cc",
     "files/file_path_unittest.cc",
     "files/file_path_watcher_unittest.cc",
     "files/file_proxy_unittest.cc",
     "files/file_unittest.cc",
     "files/file_util_proxy_unittest.cc",
     "files/file_util_unittest.cc",
     "files/important_file_writer_unittest.cc",
     "files/memory_mapped_file_unittest.cc",
     "files/scoped_platform_handle_unittest.cc",
@@ skipping 756 matching lines @@
 }
 
 fuzzer_test("base_json_correctness_fuzzer") {
   sources = [
     "json/correctness_fuzzer.cc",
   ]
   deps = [
     ":base",
   ]
 }