Start running the Mac-specific pixel test pages again.

content/test/gpu/gpu_tests/pixel_integration_test.py

Index: content/test/gpu/gpu_tests/pixel_integration_test.py
diff --git a/content/test/gpu/gpu_tests/pixel_integration_test.py b/content/test/gpu/gpu_tests/pixel_integration_test.py
index 309166e2b004dd3531a9887e47021f974c19bef5..17eed5a0264fc0da6efb08b93796f62fcf264062 100644
--- a/content/test/gpu/gpu_tests/pixel_integration_test.py
+++ b/content/test/gpu/gpu_tests/pixel_integration_test.py
@@ -5,6 +5,7 @@ import glob
 import logging
 import os
 import re
+import sys
 
 from gpu_tests import cloud_storage_integration_test_base
 from gpu_tests import pixel_expectations
@@ -114,6 +115,8 @@ class PixelIntegrationTest(
     name = 'Pixel'
     pages = pixel_test_pages.DefaultPages(name)
     pages += pixel_test_pages.ExperimentalCanvasFeaturesPages(name)
+    if sys.platform.startswith('darwin'):
+      pages += pixel_test_pages.MacSpecificPages(name)
     for p in pages:
       yield(p.name, p.url, (p))