Add 10 minute random fuzz to automatic update check event schedule.

Schedules the initial check at 7 minutes and periodic checks at 45 minutes
with +/- 5 minute fuzz.

BUG=5983
TEST=unit tests, gmerged on device, inspected logs, observed checks

Change-Id: Ifd38574c4265fec78f6e330f965c2b1054b2dddb

Review URL: http://codereview.chromium.org/3173041
diff --git a/testrunner.cc b/testrunner.cc
index 933c25d..3e40e1f 100644
--- a/testrunner.cc
+++ b/testrunner.cc
@@ -10,6 +10,7 @@
 #include <glib.h>
 #include <glib-object.h>
 #include <gtest/gtest.h>
+#include "base/at_exit.h"
 #include "base/command_line.h"
 #include "update_engine/subprocess.h"
 
@@ -17,6 +18,7 @@
   ::g_type_init();
   g_thread_init(NULL);
   dbus_g_thread_init();
+  base::AtExitManager exit_manager;
   chromeos_update_engine::Subprocess::Init();
   CommandLine::Init(argc, argv);
   ::testing::InitGoogleTest(&argc, argv);