[run-webkit-tests] Let --reset-results reset flag-specific baselines

If --additional-driver-flag is specified, it was weird to still let
--reset-results reset the existing baselines. There seems no use case
for that.

Now let --reset-results reset flag-specific baselines if --additional-
driver-flag is specified.

Bug: 660231
Change-Id: I6ee5a5f563a7f972fcece763256d7f99f3e97cbe
Reviewed-on: https://chromium-review.googlesource.com/740841
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512061}

docs/testing/layout_tests.md

@@ -498,7 +498,7 @@ doesn't support rebaselining flag-specific expectations.
 
 ```bash
 cd src/third_party/WebKit
-Tools/Script/run-webkit-tests --additional-driver-flag=--enable-flag --copy-baselines --reset-results foo/bar/test.html
+Tools/Script/run-webkit-tests --additional-driver-flag=--enable-flag --reset-results foo/bar/test.html
 ```
 
 New baselines will be created in the flag-specific baselines directory, e.g.

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/controllers/single_test_runner.py

@@ -197,12 +197,11 @@ def _save_baseline_data(self, data, extension):
         port = self._port
         fs = self._filesystem
 
-        if self._options.copy_baselines:
-            flag_specific_dir = port.baseline_flag_specific_dir()
-            if flag_specific_dir:
-                output_dir = fs.join(flag_specific_dir, fs.dirname(self._test_name))
-            else:
-                output_dir = fs.join(port.baseline_version_dir(), fs.dirname(self._test_name))
+        flag_specific_dir = port.baseline_flag_specific_dir()
+        if flag_specific_dir:
+            output_dir = fs.join(flag_specific_dir, fs.dirname(self._test_name))
+        elif self._options.copy_baselines:
+            output_dir = fs.join(port.baseline_version_dir(), fs.dirname(self._test_name))
         else:
             output_dir = fs.dirname(port.expected_filename(self._test_name, extension))
 

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/run_webkit_tests.py

@@ -231,6 +231,7 @@ def parse_args(args):
                 action='store_true',
                 default=False,
                 help=('Reset baselines to the generated results in their existing location. '
+                      'If --additional-driver-flag is specific, reset the flag-specific baselines. '
                       'If --copy-baselines is specified, the copied baselines will be reset.')),
             optparse.make_option(
                 '--results-directory',

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/run_webkit_tests_unittest.py

@@ -1260,7 +1260,6 @@ def test_new_flag_specific_baseline(self):
             'text-image-checksum_fail-txt')
         details, log_stream, _ = logging_run(
             ['--additional-driver-flag=--flag',
-             '--copy-baselines',
              '--reset-results',
              'failures/unexpected/text-image-checksum.html'],
             tests_included=True, host=host)
@@ -1319,7 +1318,6 @@ def test_new_flag_specific_baseline_optimize(self):
 
         details, log_stream, _ = logging_run(
             ['--additional-driver-flag=--flag',
-             '--copy-baselines',
              '--reset-results',
              'failures/unexpected/text-image-checksum.html'],
             tests_included=True, host=host)