Update GN roller for new JSON endpoints.

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 168 matching lines @@
     with open('DEPS', 'w') as fp:
       fp.write(new_deps)
 
   def WaitForBuildToFinish(self):
     ret = self.CheckoutBuildBranch()
     if ret:
       return ret
 
     print('Checking build')
     results = self.CheckBuild()
-    while (len(results) < 3 or
-           any(r['state'] in ('pending', 'started')
+    while (any(r['state'] in ('pending', 'started')
                for r in results.values())):
       print()
       print('Sleeping for 30 seconds')
       time.sleep(30)
       print('Checking build')
       results = self.CheckBuild()
 
     ret = 0 if all(r['state'] == 'success' for r in results.values()) else 1
     if ret:
       print('Build failed.')
@@ skipping 20 matching lines @@
   def CheckBuild(self):
     _, out, _ = self.Call('git-cl issue')
 
     issue = int(out.split()[2])
 
     _, out, _ = self.Call('git config user.email')
     email = ''
     rpc_server = upload.GetRpcServer(CODE_REVIEW_SERVER, email)
     try:
       props = json.loads(rpc_server.Send('/api/%d' % issue))
-    except Exception as _e:
-      raise
+    except Exception as e:
+      print('Failed to load patch data: %s' % e)
+      return {}
 
     patchset = int(props['patchsets'][-1])
 
     try:
       try_job_results = json.loads(rpc_server.Send(
           '/api/%d/%d/try_job_results' % (issue, patchset)))
-    except Exception as _e:
-      raise
+    except Exception as e:
+      print('Failed to load try job results: %s' % e)
+      return {}
 
     if not try_job_results:
       print('No try jobs found on most recent patchset')
       return {}
 
     results = {}
     for job in try_job_results:
       builder = job['builder']
       if builder == 'linux_chromium_gn_upload':
         platform = 'linux64'
       elif builder == 'mac_chromium_gn_upload':
         platform = 'mac'
       elif builder == 'win8_chromium_gn_upload':
         platform = 'win'
       else:
         print('Unexpected builder: %s')
         continue
 
       TRY_JOB_RESULT_STATES = ('started', 'success', 'warnings', 'failure',
                                'skipped', 'exception', 'retry', 'pending')
       state = TRY_JOB_RESULT_STATES[int(job['result']) + 1]
       url_str = ' %s' % job['url']
       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)
+        jsurl = url_str.replace('http://build.chromium.org/',
+                                'http://chrome-build-extract.appspot.com/')
+        jsurl = jsurl + '?json=1'
+        try:
+          fp = urllib2.urlopen(jsurl)
+        except urllib2.HTTPError as e:
+          print('Failed to open %s: %s' % (jsurl, e))
+          return {}
+
         js = json.loads(fp.read())
         fp.close()
         sha1_step_name = 'gn sha1'
         for step in js['steps']:
           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
             # with the step_name.
             sha1_step_text_prefix = sha1_step_name + '<br>'
@@ skipping 172 matching lines @@
   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
+    return proc.returncode, out or '', err or ''
 
 
 if __name__ == '__main__':
   roller = GNRoller()
   sys.exit(roller.Roll())