mus: Forward user activity from window server to detector.

ui/aura/mus/user_activity_forwarder.cc

Index: ui/aura/mus/user_activity_forwarder.cc
diff --git a/ui/aura/mus/user_activity_forwarder.cc b/ui/aura/mus/user_activity_forwarder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e44bc18b12d2db3c2be24afdee1881aefac4bff0
--- /dev/null
+++ b/ui/aura/mus/user_activity_forwarder.cc
@@ -0,0 +1,34 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/aura/mus/user_activity_forwarder.h"
+
+#include <cmath>
+#include <cstdint>
+
+#include "ui/base/user_activity/user_activity_detector.h"
+
+namespace aura {
+
+UserActivityForwarder::UserActivityForwarder(
+    ui::mojom::UserActivityMonitorPtr monitor,
+    ui::UserActivityDetector* detector)
+    : monitor_(std::move(monitor)), binding_(this), detector_(detector) {
+  DCHECK(detector_);
+
+  // Round UserActivityDetector's notification interval up to the nearest
+  // second (the granularity exposed by UserActivityMonitor).
+  const uint32_t kNotifyIntervalSec = static_cast<uint32_t>(
+      ceil(ui::UserActivityDetector::kNotifyIntervalMs / 1000.0));
+  monitor_->AddUserActivityObserver(kNotifyIntervalSec,
+                                    binding_.CreateInterfacePtrAndBind());
+}
+
+UserActivityForwarder::~UserActivityForwarder() {}
+
+void UserActivityForwarder::OnUserActivity() {
+  detector_->HandleExternalUserActivity();
+}
+
+}  // namespace aura