Convert most Chromium presubmit files to use new multiple-tryserver-compatible protocol

net/PRESUBMIT.py

 # Copyright (c) 2012 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.
 
 """Chromium presubmit script for src/net.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details on the presubmit API built into gcl.
 """
 
-def GetPreferredTrySlaves(project, change):
-  slaves = [
-    'linux_rel:sync_integration_tests',
-    'mac_rel:sync_integration_tests',
-    'win_rel:sync_integration_tests',
-  ]
+def GetPreferredTryMasters(project, change):
+  masters = {
+    'tryserver.chromium': {
+      'linux_rel': set(['sync_integration_tests']),
+      'mac_rel': set(['sync_integration_tests']),
+      'win_rel': set(['sync_integration_tests']),
+    }
+  }
   # Changes that touch NSS files will likely need a corresponding OpenSSL edit.
   # Conveniently, this one glob also matches _openssl.* changes too.
   if any('nss' in f.LocalPath() for f in change.AffectedFiles()):
-    slaves.append('linux_redux')
-  return slaves
+    masters['tryserver.chromium'].setdefault(
+      'linux_redux', set()).add('defaulttests')
+  return masters