Add unit test to check for broker FD leak

sandbox/linux/tests/unit_tests_unittest.cc

Index: sandbox/linux/tests/unit_tests_unittest.cc
diff --git a/sandbox/linux/tests/unit_tests_unittest.cc b/sandbox/linux/tests/unit_tests_unittest.cc
index 5ec5648e454f61b62bcac5f32501268ad8e268f9..78a3645e2c5e95fa8e4d83585054de7373bf5c77 100644
--- a/sandbox/linux/tests/unit_tests_unittest.cc
+++ b/sandbox/linux/tests/unit_tests_unittest.cc
@@ -8,6 +8,7 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+#include "base/logging.h"
 #include "base/posix/eintr_wrapper.h"
 #include "sandbox/linux/tests/unit_tests.h"
 
@@ -33,6 +34,10 @@ SANDBOX_DEATH_TEST(UnitTests,
   raise(kExpectedSignalNumber);
 }
 
+SANDBOX_TEST_ALLOW_NOISE(UnitTests, NoisyTest) {
+  LOG(ERROR) << "The cow says moo!";
+}
+
 // Test that a subprocess can be forked() and can use exit(3) instead of
 // _exit(2).
 TEST(UnitTests, SubProcessCanExit) {