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 c0c5b660f277db43a4b9b92b5fb26e5c027b31fc..14061bbf6430c6110376179f95f90aa99be23182 100644
--- a/content/test/gpu/gpu_tests/context_lost.py
+++ b/content/test/gpu/gpu_tests/context_lost.py
@@ -16,7 +16,7 @@ from telemetry.page import page_test
 data_path = os.path.join(
     util.GetChromiumSrcDir(), 'content', 'test', 'data', 'gpu')
 
-wait_timeout = 20  # seconds
+wait_timeout = 27  # seconds

[Ken Russell (switch to Gerrit), 2015/05/15 23:55:55]

If the browser windows that Telemetry opens aren't made the key window, it
sounds to me like all of the GPU tests will run more slowly. I also wonder
whether other test suites that open windows may be affected. Could you please:

 - Watch this test suite and increase the timeout further (up to 60 seconds,
say) if the test becomes flaky
 - File a follow-on bug to investigate why the newly opened window isn't being
made key

Thanks.

 
 harness_script = r"""
   var domAutomationController = {};