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

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

 # Copyright 2016 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.
 
 import optparse
 import unittest
 
 from webkitpy.common.net.buildbot import Build
 from webkitpy.common.net.layout_test_results import LayoutTestResults
 from webkitpy.common.system.executive_mock import MockExecutive, MockExecutive2
@@ skipping 466 matching lines @@
         # Note that we have only one run_in_parallel() call
         self.assertEqual(
             self.tool.executive.calls,
             [
                 [['python', 'echo', 'copy-existing-baselines-internal', '--suffixes', 'txt,png',
                   '--builder', 'MOCK Win7', '--test', 'userscripts/first-test.html', '--verbose']],
                 [['python', 'echo', 'rebaseline-test-internal', '--suffixes', 'txt,png',
                   '--builder', 'MOCK Win7', '--test', 'userscripts/first-test.html', '--verbose', '--results-directory', '/tmp']]
             ])
 
+    def test_unstaged_baselines(self):
+        scm = self.tool.scm()
+        scm.unstaged_changes = lambda: {
+            'third_party/WebKit/LayoutTests/x/foo-expected.txt': 'M',
+            'third_party/WebKit/LayoutTests/x/foo-expected.something': '?',
+            'third_party/WebKit/LayoutTests/x/foo-expected.png': '?',
+            'third_party/WebKit/LayoutTests/x/foo.html': 'M',
+            'docs/something.md': '?',
+        }
+        self.assertEqual(
+            self.command.unstaged_baselines(),
+            [
+                '/mock-checkout/third_party/WebKit/LayoutTests/x/foo-expected.png',
+                '/mock-checkout/third_party/WebKit/LayoutTests/x/foo-expected.txt',
+            ])
+
 
 class TestRebaselineJsonUpdatesExpectationsFiles(BaseTestCase):
     command_constructor = RebaselineJson
 
     def setUp(self):
         super(TestRebaselineJsonUpdatesExpectationsFiles, self).setUp()
         self.tool.executive = MockExecutive2()
 
         def mock_run_command(*args, **kwargs):  # pylint: disable=unused-argument
             return '{"add": [], "remove-lines": [{"test": "userscripts/first-test.html", "builder": "MOCK Mac10.11"}]}\n'
@@ skipping 429 matching lines @@
         for cmd_line, cwd in commands:
             out = self.run_command(cmd_line, cwd=cwd)
             if 'rebaseline-test-internal' in cmd_line:
                 out = '{"remove-lines": [{"test": "%s", "builder": "%s"}]}\n' % (cmd_line[8], cmd_line[6])
             command_outputs.append([0, out, ''])
 
         new_calls = self.calls[num_previous_calls:]
         self.calls = self.calls[:num_previous_calls]
         self.calls.append(new_calls)
         return command_outputs