Added log message indicating the result of running AU unittests.

This should give us better insight as for the actual value returned by
RUN_ALL_TESTS and whether it is consistent with the documented behavior.

BUG=chromium-os:29841
TEST=Ran unittest binary, observed log message

Change-Id: I942311b1f30b44f1e9ef69e0ae3b1346ee1fa1b0
Reviewed-on: https://gerrit.chromium.org/gerrit/21260
Reviewed-by: Ben Chan <benchan@chromium.org>
Commit-Ready: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
diff --git a/testrunner.cc b/testrunner.cc
index 748dd5f..725b5b5 100644
--- a/testrunner.cc
+++ b/testrunner.cc
@@ -25,5 +25,7 @@
   chromeos_update_engine::Subprocess::Init();
   CommandLine::Init(argc, argv);
   ::testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
+  int test_result = RUN_ALL_TESTS();
+  LOG(INFO) << "unittest return value: " << test_result;
+  return test_result;
 }