Test Keeping NaCl plugins used in app background pages alive when active.

chrome/chrome_tests.gypi

Index: chrome/chrome_tests.gypi
diff --git a/chrome/chrome_tests.gypi b/chrome/chrome_tests.gypi
index b970cd72142f23907f2241b83bad4dfe5c663a19..a0b5692bda7f7592d2c35ef07c0653ff4d368e09 100644
--- a/chrome/chrome_tests.gypi
+++ b/chrome/chrome_tests.gypi
@@ -1666,7 +1666,8 @@
                 'test/data/nacl/nacl_test_data.gyp:*',
                 '../ppapi/native_client/native_client.gyp:nacl_irt',
                 '../ppapi/ppapi_untrusted.gyp:ppapi_nacl_tests',
-                '../ppapi/tests/extensions/extensions.gyp:ppapi_tests_extensions_socket',
+                '../ppapi/tests/extensions/extensions.gyp:ppapi_tests_extensions_background_keepalive',
+                '../ppapi/tests/extensions/extensions.gyp:ppapi_tests_extensions_socket'
               ],
               'conditions': [
                 ['OS=="linux"', {