rebaseline.py: add ability to write new expectations to a different file

rebaseline.py: add ability to write new expectations to a different file
(instead of overwriting the original expectations file)

R=zachr@google.com

Committed: https://code.google.com/p/skia/source/detail?r=10333

[epoger, 2013-07-24 19:31:34]

https://codereview.chromium.org/19805007/diff/1/tools/rebaseline.py
File tools/rebaseline.py (right):

https://codereview.chromium.org/19805007/diff/1/tools/rebaseline.py#newcode317
tools/rebaseline.py:317: parser.add_argument('--expectations-filename-output',
Here's what this section of the --help output looks like:

  --expectations-filename EXPECTATIONS_FILENAME
                        filename (under EXPECTATIONS_ROOT) to read current
                        expectations from, and to write new expectations into
                        (unless a separate EXPECTATIONS_FILENAME_OUTPUT has
                        been specified); defaults to expected-results.json
  --expectations-filename-output EXPECTATIONS_FILENAME_OUTPUT
                        filename (under EXPECTATIONS_ROOT) to write updated
                        expectations into; by default, overwrites the input
                        file (EXPECTATIONS_FILENAME)
  --expectations-root EXPECTATIONS_ROOT
                        root of expectations directory to update-- should
                        contain one or more base-* subdirectories. Defaults to
                        expectations/gm

[Zach Reizner, 2013-07-24 19:36:32]

lgtm

[epoger, 2013-07-24 19:36:53]

Committed patchset #1 manually as r10333 (presubmit successful).