Pass nanobench --options build_number <build_number>.

slave/skia_slave_scripts/run_nanobench.py

 #!/usr/bin/env python
 # Copyright (c) 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.
 
 """Run the Skia benchmarking executable."""
 
 import os
 import sys
 
@@ skipping 50 matching lines @@
             '--scales', '1.0', '1.1']
     if self._AnyMatch('Valgrind'):
       args.extend(['--loops', '1'])  # Don't care about performance on Valgrind.
     elif self._perf_data_dir:
       args.extend([
         '--outResultsFile', self._JSONPath(),
         '--gitHash', self._got_revision,
       ])
       args.append('--key')
       args.extend(self._KeyParams())
+      args.append('--options')
+      args.extend(['build_number', str(self._build_number)])
 
     match  = []
     # Disable known problems.
     if self._AnyMatch('Android'):
       # Segfaults when run as GPU bench.  Very large texture?
       match.append('~blurroundrect')
 
     if self._AnyMatch('HD2000'):
       # GPU benches seem to hang on HD2000.  Not sure why.
       args.append('--nogpu')
@@ skipping 16 matching lines @@
     # See skia:2789
     if self._AnyMatch('Valgrind'):
       abandonGpuContext = list(args)
       abandonGpuContext.append('--abandonGpuContext')
       abandonGpuContext.append('--nocpu')
       self._flavor_utils.RunFlavoredCmd('nanobench', abandonGpuContext)
 
 
 if '__main__' == __name__:
   sys.exit(BuildStep.RunBuildStep(RunNanobench))