Allow trybot changes to run against WebKit@HEAD.

scripts/master/chromium_step.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.
 
 """Subclasses of various slave command classes."""
 
 import copy
 import errno
 import json
 import logging
@@ skipping 84 matching lines @@
       return None
     # Change revision numbers can be invalid, for a try job for instance.
     # TODO(maruel): Make this work for git hash.
     lastChange = max([change_to_revision(c) for c in changes])
     return lastChange
 
   def startVC(self, branch, revision, patch):
     warnings = []
     args = copy.copy(self.args)
     wk_revision = revision
+    if patch:
+      match = re.search(r'third_party/WebKit@(\w+)', patch[1])
+      if match:
+        wk_revision = match.group(1)
     try:
       # parent_wk_revision might be set, but empty.
       if self.getProperty('parent_wk_revision'):
         wk_revision = self.getProperty('parent_wk_revision')
     except KeyError:
       pass
     nacl_revision = revision
     try:
       # parent_nacl_revision might be set, but empty.
       if self.getProperty('parent_got_nacl_revision'):
@@ skipping 950 matching lines @@
   def evaluateCommand(self, cmd):
     observer_result = self.script_observer.annotate_status
     # Check if ProcessLogShellStep detected a failure or warning also.
     log_processor_result = ProcessLogShellStep.evaluateCommand(self, cmd)
     return BuilderStatus.combine(observer_result, log_processor_result)
 
   def commandComplete(self, cmd):
     self.script_observer.handleReturnCode(cmd.rc)
     self._removePreamble()
     return ProcessLogShellStep.commandComplete(self, cmd)