Revert of Add support for backgrounding processes on the Mac

content/test/gpu/gpu_tests/context_lost.py

Index: content/test/gpu/gpu_tests/context_lost.py
diff --git a/content/test/gpu/gpu_tests/context_lost.py b/content/test/gpu/gpu_tests/context_lost.py
index 14061bbf6430c6110376179f95f90aa99be23182..c0c5b660f277db43a4b9b92b5fb26e5c027b31fc 100644
--- a/content/test/gpu/gpu_tests/context_lost.py
+++ b/content/test/gpu/gpu_tests/context_lost.py
@@ -16,7 +16,7 @@
 data_path = os.path.join(
     util.GetChromiumSrcDir(), 'content', 'test', 'data', 'gpu')
 
-wait_timeout = 27  # seconds
+wait_timeout = 20  # seconds
 
 harness_script = r"""
   var domAutomationController = {};