buildbots: only store/upload GM results we haven't seen before, to save time

slave/skia_slave_scripts/run_gm.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.
 
 """ Run the Skia GM executable. """
 
 from build_step import BuildStep
 import build_step
 import os
 import sys
 
 
 JSON_SUMMARY_FILENAME = 'actual-results.json'
 
 
 class RunGM(BuildStep):
   def _Run(self):
     device_gm_expectations_path = self.DevicePathJoin(
         self._device_dirs.GMExpectedDir(), build_step.GM_EXPECTATIONS_FILENAME)
     output_dir = os.path.join(self._device_dirs.GMActualDir(),
                               self._gm_image_subdir)
     cmd = ['--verbose',
            '--writeChecksumBasedFilenames',
-           '--writePath', output_dir,
+           # Don't bother writing out image files that match our expectations--
+           # we know that previous runs have already uploaded those!
+           '--mismatchPath', output_dir,
+           '--missingExpectationsPath', output_dir,
            '--writeJsonSummaryPath', os.path.join(output_dir,
                                                   JSON_SUMMARY_FILENAME),
            '--ignoreErrorTypes',
                'IntentionallySkipped', 'MissingExpectations',
                'ExpectationsMismatch',
            '--readPath', device_gm_expectations_path,
            # TODO(borenet): Re-enable --resourcePath when the test passes.
            #'--resourcePath', self._device_dirs.ResourceDir(),
            ] + self._gm_args
     # msaa16 is flaky on Macs (driver bug?) so we skip the test for now
     if sys.platform == 'darwin':
       cmd.extend(['--config', 'defaults', '~msaa16'])
     elif hasattr(self, '_device') and self._device in ['razr_i', 'nexus_10',
                                                        'galaxy_nexus']:
       cmd.extend(['--config', 'defaults', 'msaa4'])
     elif (not 'NoGPU' in self._builder_name and
           not 'ChromeOS' in self._builder_name):
       cmd.extend(['--config', 'defaults', 'msaa16'])
     self.RunFlavoredCmd('gm', cmd)
 
 
 if '__main__' == __name__:
   sys.exit(BuildStep.RunBuildStep(RunGM))