Mojo: Trivial cleanup -- remove unneeded test fixture in test.

mojo/public/tests/system_core_unittest.cc

Index: mojo/public/tests/system_core_unittest.cc
diff --git a/mojo/public/tests/system_core_unittest.cc b/mojo/public/tests/system_core_unittest.cc
index 7d5a78ded56499862c89a24c1179852211705065..8c7d1e59a63d1326c6dccd13e40198501824bcd8 100644
--- a/mojo/public/tests/system_core_unittest.cc
+++ b/mojo/public/tests/system_core_unittest.cc
@@ -11,10 +11,7 @@
 namespace mojo {
 namespace {
 
-class SystemTest : public testing::Test {
-};
-
-TEST_F(SystemTest, Basic) {
+TEST(SystemTest, Basic) {
   Handle h_0;
   MojoWaitFlags wf;
   char buffer[10] = { 0 };