[blinkpy] Get rid of LAST_CHANGE

This file does not seem to exist any more and new builds should always
have chromium_revision in their JSON results.

Bug: 811976
Change-Id: If8c9a2d1d9a2e18f5171947990bf404aedc41b67
Reviewed-on: https://chromium-review.googlesource.com/c/1371072
Commit-Queue: Robert Ma <robertma@chromium.org>
Reviewed-by: Quinten Yearsley <qyearsley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615679}

third_party/blink/tools/blinkpy/common/net/buildbot.py

@@ -170,11 +170,7 @@ class BuildBot(object):
         if results_file is None:
             _log.debug('Got 404 response from:\n%s/%s', results_url, base_filename)
             return None
-        revision = NetworkTransaction(return_none_on_404=True).run(
-            lambda: self.fetch_file('%s/LAST_CHANGE' % results_url))
-        if revision is None:
-            _log.debug('Got 404 response from:\n%s/LAST_CHANGE', results_url)
-        return WebTestResults.results_from_string(results_file, revision)
+        return WebTestResults.results_from_string(results_file)
 
     def fetch_file(self, url):
         # It seems this can return None if the url redirects and then returns 404.

third_party/blink/tools/blinkpy/common/net/web_test_results.py

@@ -84,15 +84,11 @@ class WebTestResult(object):
 class WebTestResults(object):
 
     @classmethod
-    def results_from_string(cls, string, chromium_revision=None):
+    def results_from_string(cls, string):
         """Creates a WebTestResults object from a test result JSON string.
 
         Args:
             string: JSON string containing web test result.
-            chromium_revision: If given, it will override the chromium_revision
-                field in json, to indicate the last revision that has completed
-                uploading onto the storage server. chromium_revision can be a
-                git hash or position number.
         """
 
         if not string:
@@ -103,7 +99,7 @@ class WebTestResults(object):
         if not json_dict:
             return None
 
-        return cls(json_dict, chromium_revision)
+        return cls(json_dict)
 
     def __init__(self, parsed_json, chromium_revision=None):
         self._results = parsed_json