mus: Forward user activity from window server to detector.

ui/aura/BUILD.gn

Index: ui/aura/BUILD.gn
diff --git a/ui/aura/BUILD.gn b/ui/aura/BUILD.gn
index 4b87bc15c9821c690d2301e9653d5a865feb82dd..a170f53aafb0dc3573ff784b02eadea4d83f4551 100644
--- a/ui/aura/BUILD.gn
+++ b/ui/aura/BUILD.gn
@@ -96,6 +96,8 @@ component("aura") {
     "mus/property_utils.h",
     "mus/text_input_client_impl.cc",
     "mus/text_input_client_impl.h",
+    "mus/user_activity_forwarder.cc",
+    "mus/user_activity_forwarder.h",
     "mus/window_compositor_frame_sink.cc",
     "mus/window_compositor_frame_sink.h",
     "mus/window_manager_delegate.cc",
@@ -335,6 +337,7 @@ test("aura_unittests") {
     "gestures/gesture_recognizer_unittest.cc",
     "mus/os_exchange_data_provider_mus_unittest.cc",
     "mus/property_converter_unittest.cc",
+    "mus/user_activity_forwarder_unittest.cc",
     "mus/window_tree_client_unittest.cc",
     "mus/window_tree_host_mus_unittest.cc",
     "test/run_all_unittests.cc",
@@ -348,7 +351,9 @@ test("aura_unittests") {
     ":test_support",
     "//base/test:test_support",
     "//mojo/common",
+    "//mojo/edk/system",
     "//net",
+    "//services/ui/common:task_runner_test_base",
     "//services/ui/public/cpp",
     "//skia",
     "//testing/gtest",