Record screenshots on failures on swarming bots.

tools/mb/mb.py

 #!/usr/bin/env python
 # Copyright 2015 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.
 
 """MB - the Meta-Build wrapper around GYP and GN
 
 MB is a wrapper script for GYP and GN that can be used to generate build files
 for sets of canned configurations and analyze them.
 """
@@ skipping 1073 matching lines @@
     if test_type == 'nontest':
       self.WriteFailureAndRaise('We should not be isolating %s.' % target,
                                 output_path=None)
 
     if android and test_type != "script":
       # TODO(crbug.com/693203): Reenable logcat logdog uploading when outage
       # has been resolved.
       cmdline = [
           self.PathJoin('bin', 'run_%s' % target),
           '--logcat-output-file', '${ISOLATED_OUTDIR}/logcats',
+          '--screenshot-dir', '$(mktemp -d)',

[jbudorick, 2017/03/01 20:19:21]

I don't think we ought to pass this for anything but instrumentation tests...

[bpastene, 2017/03/01 20:35:54]

You could add the arg to all instrumentation tests in the testing/buildbot json
specs like:
https://chromium.googlesource.com/chromium/src/+/a515dc389dc5e4a6ecf5583f3569...

 It'd be pretty tedious and painful, but it should work.

[jbudorick, 2017/03/01 20:45:39]

Ideally, this would be less tedious once we're generating the test spec, but
yeah, that's kinda what I was thinking.

           '--target-devices-file', '${SWARMING_BOT_FILE}',
           '-v'
       ]
     elif use_xvfb and test_type == 'windowed_test_launcher':
       extra_files = [
           '../../testing/test_env.py',
           '../../testing/xvfb.py',
       ]
       cmdline = [
         '../../testing/xvfb.py',
@@ skipping 456 matching lines @@
   # Then check to see if the arg contains any metacharacters other than
   # double quotes; if it does, quote everything (including the double
   # quotes) for safety.
   if any(a in UNSAFE_FOR_CMD for a in arg):
     arg = ''.join('^' + a if a in ALL_META_CHARS else a for a in arg)
   return arg
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))