Fetch retry summary and use it to determine what tests to rebaseline.

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

Index: third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py b/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py
index 03267c4e376e540782b4d1f51e53c097fa9884ac..59478e4ddccc58af351592ea9f0779246ab96675 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py
@@ -8,6 +8,7 @@ This command interacts with the Rietveld API to get information about try jobs
 with layout test results.
 """
 
+import json
 import logging
 import optparse
 
@@ -183,7 +184,7 @@ class RebaselineCL(AbstractParallelRebaselineCommand):
         return self._tool.builders.all_try_builder_names()
 
     def _tests_to_rebaseline(self, build):
-        """Fetches a list of LayoutTestResult objects for unexpected results with new baselines."""
+        """Fetches a list of tests that should be rebaselined."""
         buildbot = self._tool.buildbot
         results_url = buildbot.results_url(build.builder_name, build.build_number)
         layout_test_results = buildbot.fetch_layout_test_results(results_url)
@@ -192,7 +193,27 @@ class RebaselineCL(AbstractParallelRebaselineCommand):
             return []
         failure_results = layout_test_results.unexpected_mismatch_results()
         missing_results = layout_test_results.missing_results()
-        return sorted(r.test_name() for r in failure_results + missing_results)
+        tests = sorted(r.test_name() for r in failure_results + missing_results)
+
+        new_failures = self._fetch_tests_with_new_failures(build)
+        if new_failures is None:
+            _log.warning('No retry summary available for build %s.', build)
+        else:
+            tests = [t for t in tests if t in new_failures]
+        return tests
+
+    def _fetch_tests_with_new_failures(self, build):
+        """Fetches a list of tests that failed with a patch in a given try job but not without."""
+        buildbot = self._tool.buildbot
+        content = buildbot.fetch_retry_summary_json(build)
+        if content is None:
+            return None
+        try:
+            retry_summary = json.loads(content)
+            return retry_summary['failures']
+        except (ValueError, KeyError):
+            _log.warning('Unexepected retry summary content:\n%s', content)
+            return None
 
     @staticmethod
     def _log_test_prefix_list(test_prefix_list):
@@ -200,7 +221,8 @@ class RebaselineCL(AbstractParallelRebaselineCommand):
         if not test_prefix_list:
             _log.info('No tests to rebaseline; exiting.')
             return
-        _log.info('Tests to rebaseline:')
+        _log.debug('Tests to rebaseline:')
         for test, builds in test_prefix_list.iteritems():
-            builds_str = ', '.join(sorted('%s (%s)' % (b.builder_name, b.build_number) for b in builds))
-            _log.info('  %s: %s', test, builds_str)
+            _log.debug('  %s:', test)
+            for build in sorted(builds):
+                _log.debug('    %s', build)