scouting: Change background_task implementation

Instead of manually implementing a ticker, this patch switches over to
using `time.Ticker`. The functionality should be identical.

This patch also adds a small test to make sure that the bare
functionality is working.

Signed-off-by: Philipp Schrader <philipp.schrader@gmail.com>
Change-Id: I54acfc5280b3541f3021dbe35d79e7db0adcc5f6
diff --git a/scouting/background_task/background_task_test.go b/scouting/background_task/background_task_test.go
new file mode 100644
index 0000000..5326d14
--- /dev/null
+++ b/scouting/background_task/background_task_test.go
@@ -0,0 +1,21 @@
+package background_task
+
+import (
+	"testing"
+	"time"
+)
+
+func TestBackgroundTask(t *testing.T) {
+	task := New(100 * time.Millisecond)
+	defer task.Stop()
+
+	counter := 0
+	task.Start(func() {
+		counter += 1
+	})
+
+	// Block until we've seeen 10 timer ticks.
+	for counter < 10 {
+		time.Sleep(100 * time.Millisecond)
+	}
+}