Fix the script used to roll GN.

tools/gn/bin/roll_gn.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 """An auto-roller for GN binaries into Chromium.
 
 This script is used to update the GN binaries that a Chromium
 checkout uses. In order to update the binaries, one must follow
 four steps in order:
@@ skipping 252 matching lines @@
       build = url_str.split('/')[-1]
 
       sha1 = '-'
       results.setdefault(platform, {'build': -1, 'sha1': '', 'url': url_str})
 
       if state == 'success':
         jsurl = url_str.replace('/builders/', '/json/builders/')
         fp = urllib2.urlopen(jsurl)
         js = json.loads(fp.read())
         fp.close()
+        sha1_step_name = 'gn sha1'
         for step in js['steps']:
-          if step['name'] == 'gn sha1':
-            sha1 = step['text'][1]
+          if step['name'] == sha1_step_name:
+            # TODO: At some point infra changed the step text to
+            # contain the step name; once all of the masters have been
+            # restarted we can probably assert that the step text

[brettw, 2016/07/03 23:26:29]

This doesn't quite parse in English "assert that the step text with the step
name"

+            # with the step_name.
+            sha1_step_text_prefix = sha1_step_name + '<br>'
+            if step['text'][-1].startswith(sha1_step_text_prefix):
+              sha1 = step['text'][-1][len(sha1_step_text_prefix):]
+            else:
+              sha1 = step['text'][-1]
 
       if results[platform]['build'] < build:
         results[platform]['build'] = build
         results[platform]['sha1'] = sha1
         results[platform]['state'] = state
         results[platform]['url'] = url_str
 
     for platform, r in results.items():
       print(platform)
       print('  sha1:  %s' % r['sha1'])
@@ skipping 137 matching lines @@
     gn_changes = self.GetGNChanges()
 
     return (
       'Roll buildtools %s..%s\n'
       '\n'
       '  In order to roll GN %s..%s (r%s:r%s) and pick up\n'
       '  the following changes:\n'
       '\n'
       '%s'
       '\n'
-      'TBR=%s\n'
-      'CQ_EXTRA_TRYBOTS=tryserver.chromium.mac:mac_chromium_gn_dbg;'
-      'tryserver.chromium.win:win8_chromium_gn_dbg\n' % (
+      'TBR=%s\n' % (
         old_buildtools_commitish[:COMMITISH_DIGITS],
         new_buildtools_commitish[:COMMITISH_DIGITS],
         self.old_gn_commitish[:COMMITISH_DIGITS],
         self.new_gn_commitish[:COMMITISH_DIGITS],
         self.old_gn_version,
         self.new_gn_version,
         gn_changes,
         self.reviewer,
       ))
 
   def GetGNChanges(self):
     _, out, _ = self.Call(
         "git log --pretty='  %h %s' " +
         "%s..%s tools/gn" % (self.old_gn_commitish, self.new_gn_commitish))
     return out
 
   def Call(self, cmd, cwd=None):
     proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, shell=True,
                             cwd=(cwd or self.chromium_src_dir))
     out, err = proc.communicate()
     return proc.returncode, out, err
 
 
 if __name__ == '__main__':
   roller = GNRoller()
   sys.exit(roller.Roll())