Gathering information about test filter files into a README.md file.

base/test/launcher/unit_test_launcher.cc

 // Copyright 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.
 
 #include "base/test/launcher/unit_test_launcher.h"
 
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
@@ skipping 55 matching lines @@
           "    Sets the number of parallel test jobs to N.\n"
           "\n"
           "  --single-process-tests\n"
           "    Runs the tests and the launcher in the same process. Useful\n"
           "    for debugging a specific test in a debugger.\n"
           "\n"
           " Other flags:\n"
           "  --test-launcher-filter-file=PATH\n"
           "    Like --gtest_filter, but read the test filter from PATH.\n"
           "    One pattern per line; lines starting with '-' are exclusions.\n"
+          "    See also //testing/buildbot/filters/README.md file.\n"
           "\n"
           "  --test-launcher-batch-limit=N\n"
           "    Sets the limit of test batch to run in a single process to N.\n"
           "\n"
           "  --test-launcher-debug-launcher\n"
           "    Disables autodetection of debuggers and similar tools,\n"
           "    making it possible to use them to debug launcher itself.\n"
           "\n"
           "  --test-launcher-retry-limit=N\n"
           "    Sets the limit of test retries on failures to N.\n"
@@ skipping 548 matching lines @@
     TestLauncher* test_launcher,
     const std::vector<std::string>& test_names) {
   ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,
       Bind(&RunUnitTestsSerially, test_launcher, platform_delegate_, test_names,
            use_job_objects_ ? TestLauncher::USE_JOB_OBJECTS : 0));
   return test_names.size();
 }
 
 }  // namespace base