Convert build.chromium.org URLs to new URL format.

PRESUBMIT.py

 # Copyright (c) 2010 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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
 
@@ skipping 150 matching lines @@
   IGNORED_BUILDERS = [
     'Chromium XP',
     'Chromium Mac',
     'Chromium Arm (dbg)',
     'Chromium Linux',
     'Chromium Linux x64',
   ]
   results.extend(input_api.canned_checks.CheckBuildbotPendingBuilds(
       input_api,
       output_api,
-      'http://build.chromium.org/buildbot/waterfall/json/builders?filter=1',
+      'http://build.chromium.org/p/chromium/json/builders?filter=1',
       6,
       IGNORED_BUILDERS))
   return results
 
 
 def GetPreferredTrySlaves():
   return ['win', 'linux', 'mac']