rebaseline_server: create ImagePairSet-- holds a number of ImagePairs to examine

See https://goto.google.com/ChangingRbsJson and bug 1919 for additional context

BUG=skia:1919
NOTRY=True
R=rmistry@google.com

Author: epoger@google.com

Review URL: https://codereview.chromium.org/139343018

git-svn-id: http://skia.googlecode.com/svn/trunk@13434 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/rebaseline_server/imagepair_test.py b/gm/rebaseline_server/imagepair_test.py
index fc1f275..d29438e 100755
--- a/gm/rebaseline_server/imagepair_test.py
+++ b/gm/rebaseline_server/imagepair_test.py
@@ -32,11 +32,11 @@
     shutil.rmtree(self._temp_dir)
 
   def shortDescription(self):
-    """Tell unittest framework to not print docstrings for test cases."""
+    """Tells unittest framework to not print docstrings for test cases."""
     return None
 
   def test_endToEnd(self):
-    """Test ImagePair, using a real ImageDiffDB to download real images.
+    """Tests ImagePair, using a real ImageDiffDB to download real images.
 
     TODO(epoger): Either in addition to or instead of this end-to-end test,
     we should perform some tests using either:
@@ -65,7 +65,7 @@
             },
             # expected output:
             {
-                'extraColumnValues': {
+                'extraColumns': {
                     'builder': 'MyBuilder',
                     'test': 'MyTest',
                 },
@@ -115,11 +115,11 @@
                     'percentDifferingPixels': 100.00,
                     'weightedDiffMeasure': 66.66666666666667,
                 },
-                'expectationsData': {
+                'expectations': {
                     'bugs': [1001, 1002],
                     'ignoreFailure': True,
                 },
-                'extraColumnValues': {
+                'extraColumns': {
                     'builder': 'MyBuilder',
                     'test': 'MyTest',
                 },