teach rebaseline_server how to compare results of multiple render_pictures runs

gm/rebaseline_server/compare_rendered_pictures_test.py

 #!/usr/bin/python
 
 """
 Copyright 2014 Google Inc.
 
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 
-Test compare_configs.py
+Test compare_rendered_pictures.py
 
 TODO(epoger): Create a command to update the expected results (in
 self._output_dir_expected) when appropriate.  For now, you should:
 1. examine the results in self._output_dir_actual and make sure they are ok
 2. rm -rf self._output_dir_expected
 3. mv self._output_dir_actual self._output_dir_expected
 Although, if you're using an SVN checkout, this will blow away .svn directories
 within self._output_dir_expected, which wouldn't be good...
 
 """
 
 import os
 import sys
 
 # Imports from within Skia
 import base_unittest
-import compare_configs
+import compare_rendered_pictures
 import results
 import gm_json  # must import results first, so that gm_json will be in sys.path
 
 
-class CompareConfigsTest(base_unittest.TestCase):
+class CompareRenderedPicturesTest(base_unittest.TestCase):
 
-  def test_gm(self):
-    """Process results of a GM run with the ConfigComparisons object."""
-    results_obj = compare_configs.ConfigComparisons(
-        configs=('8888', 'gpu'),
-        actuals_root=os.path.join(self._input_dir, 'gm-actuals'),
+  def test_endToEnd(self):
+    """Compare results of two render_pictures runs."""
+    results_obj = compare_rendered_pictures.RenderedPicturesComparisons(
+        actuals_root=os.path.join(self._input_dir, 'render_pictures_output'),
+        subdirs=('before_patch', 'after_patch'),
         generated_images_root=self._temp_dir,
         diff_base_url='/static/generated-images')
     results_obj.get_timestamp = mock_get_timestamp
     gm_json.WriteToFile(
         results_obj.get_packaged_results_of_type(
             results.KEY__HEADER__RESULTS_ALL),
-        os.path.join(self._output_dir_actual, 'gm.json'))
+        os.path.join(self._output_dir_actual, 'compare_rendered_pictures.json'))
 
 
 def mock_get_timestamp():
   """Mock version of BaseComparisons.get_timestamp() for testing."""
   return 12345678
 
 
 def main():
-  base_unittest.main(CompareConfigsTest)
+  base_unittest.main(CompareRenderedPicturesTest)
 
 
 if __name__ == '__main__':
   main()