Fix seed_steps for generator annotation recipes.

scripts/common/annotator.py

 #!/usr/bin/env python
 # Copyright (c) 2013 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.
 
 """Contains generating and parsing systems of the Chromium Buildbot Annotator.
 
 When executed as a script, this reads step name / command pairs from a file and
 executes those lines while annotating the output. The input is json:
 
@@ skipping 376 matching lines @@
         print 'step was: %s' % json.dumps(step_dict)
         s.step_failure()
         build_failure = True
   except OSError:
     # File wasn't found, error has been already reported to stream.
     build_failure = True
 
   return build_failure, ret
 
 
-def run_steps(steps, build_failure):
+def run_steps(steps, build_failure, seed_steps=None):
   for step in steps:
     error = _validate_step(step)
     if error:
       print 'Invalid step - %s\n%s' % (error, json.dumps(step, indent=2))
       sys.exit(1)
 
-  seed_steps = []
-  for step in steps:
-    seed_steps.append(step['name'])
-    seed_steps.extend(step.get('seed_steps', []))
+  if seed_steps is None:
+    seed_steps = [s['name'] for s in steps]
 
   stream = StructuredAnnotationStream(seed_steps=seed_steps)
   ret_codes = []
   for step in steps:
     build_failure, ret = _run_step(stream, build_failure, **step)
     ret_codes.append(ret)
   return build_failure, ret_codes
 
 
 def main():
@@ skipping 11 matching lines @@
     steps.extend(json.load(sys.stdin))
   else:
     with open(args[0], 'rb') as f:
       steps.extend(json.load(f))
 
   return 1 if run_steps(steps, False)[0] else 0
 
 
 if __name__ == '__main__':
   sys.exit(main())