Sometimes, InputApi users need to create temporary files, write to them and
pass them to another process, like this:

  with input_api.tempfile.NamedTemporaryFile() as f:
    f.write('foo')
    input_api.subprocess.check_output(['/path/to/script',
        '--reading-from', f.name])

While this works fine on Unix, on Windows subprocess cannot open and read
the file while we have it open for writing.

To work around this, we now offer a CreateTemporaryFile() that wraps a call
to tempfile.NamedTemporaryFile(delete=False), and we then take care of
removing all files created this way at the end of a presubmit run.

The idea is for users to do something like this:

  with input_api.CreateTemporaryFile() as f:
    f.write('foo')
    f.close()
    input_api.subprocess.check_output(['/path/to/script',
        '--reading-from', f.name])

with the temporary file being removed automatically in a transparent fashion
later.

Bug: 780629
Change-Id: I0d705a5d52928a43f39a51f94a2c48d277bd5ced
Reviewed-on: https://chromium-review.googlesource.com/758637
Commit-Queue: Raphael Kubo da Costa (rakuco) <raphael.kubo.da.costa@intel.com>
Reviewed-by: Aaron Gable <agable@chromium.org>