Only add unstaged baseline changes to the git index when rebaselining.

third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline.py

 # Copyright (c) 2010 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 12 matching lines @@
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR/ OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 from __future__ import print_function
 import json
 import logging
 import optparse
+import re
 import sys
 import traceback
 
 from webkitpy.common.memoized import memoized
 from webkitpy.common.net.buildbot import Build
 from webkitpy.common.system.executive import ScriptError
 from webkitpy.layout_tests.models.testharness_results import is_all_pass_testharness_result
 from webkitpy.layout_tests.models.test_expectations import TestExpectations, BASELINE_SUFFIX_LIST, SKIP
 from webkitpy.layout_tests.port import factory
 from webkitpy.tool.commands.command import Command
@@ skipping 473 matching lines @@
             self._update_expectations_files(lines_to_remove)
 
         if options.optimize:
             # TODO(wkorman): Consider changing temporary branch to base off of HEAD rather than
             # origin/master to ensure we run baseline optimization processes with the same code as
             # auto-rebaseline itself.
             self._run_in_parallel(self._optimize_baselines(test_prefix_list, options.verbose))
 
         self._remove_all_pass_testharness_baselines(test_prefix_list)
 
-        self._tool.scm().add_all(pathspec=self._layout_tests_dir())
+        self._tool.scm().add_list(self.unstaged_baselines())
+
+    def unstaged_baselines(self):
+        """Returns absolute paths for unstaged (including untracked) baselines."""
+        baseline_re = re.compile(r'.*[\\/]LayoutTests[\\/].*-expected\.(txt|png|wav)$')
+        unstaged_changes = self._tool.scm().unstaged_changes()
+        return sorted(self._tool.scm().absolute_path(path) for path in unstaged_changes if re.match(baseline_re, path))
 
     def _remove_all_pass_testharness_baselines(self, test_prefix_list):
         """Removes all of the all-PASS baselines for the given builders and tests.
 
         In general, for testharness.js tests, the absence of a baseline
         indicates that the test is expected to pass. When rebaselining,
         new all-PASS baselines may be downloaded, but they should not be kept.
         """
         filesystem = self._tool.filesystem
         baseline_paths = self._all_baseline_paths(test_prefix_list)
@@ skipping 173 matching lines @@
             for test in args:
                 if test not in test_prefix_list:
                     test_prefix_list[test] = {}
                 build = Build(builder)
                 test_prefix_list[test][build] = suffixes_to_update
 
         if options.verbose:
             _log.debug("rebaseline-json: " + str(test_prefix_list))
 
         self.rebaseline(options, test_prefix_list)