Make UserActivityDetector a singleton

athena/test/base/athena_test_helper.cc

Index: athena/test/base/athena_test_helper.cc
diff --git a/athena/test/base/athena_test_helper.cc b/athena/test/base/athena_test_helper.cc
index 538ed1c91cfb2db64d5bacd98b1e036a83e98748..457e614b65272e8dba7904ab138187e11edecacb 100644
--- a/athena/test/base/athena_test_helper.cc
+++ b/athena/test/base/athena_test_helper.cc
@@ -22,6 +22,7 @@
 #include "ui/compositor/scoped_animation_duration_scale_mode.h"
 #include "ui/wm/core/focus_controller.h"
 #include "ui/wm/core/input_method_event_filter.h"
+#include "ui/wm/core/user_activity_detector.h"
 
 #if defined(USE_X11)
 #include "ui/base/x/x11_util.h"
@@ -60,6 +61,10 @@ void AthenaTestHelper::SetUp(ui::ContextFactory* context_factory) {
   aura::test::EnvTestHelper(aura::Env::GetInstance())
       .SetInputStateLookup(scoped_ptr<aura::InputStateLookup>());
 
+  // UserActivityDetector must be created before the athena environment is
+  // started.
+  wm::UserActivityDetector::Create();
+
   // TODO(oshima): Use a BlockingPool task runner.
   athena::StartAthenaEnv(file_thread_->message_loop_proxy());
   athena::ExtensionsDelegate::CreateExtensionsDelegateForTest();
@@ -72,6 +77,7 @@ void AthenaTestHelper::TearDown() {
   teardown_called_ = true;
 
   athena::ShutdownAthena();
+  wm::UserActivityDetector::Shutdown();
   aura::Env::DeleteInstance();
 
 #if defined(USE_X11)