Add docs to SystemClock.h
Test: n/a
Change-Id: I16a41e9b98c88270857fe2a1d6b382bfe469bca6
diff --git a/libutils/include/utils/SystemClock.h b/libutils/include/utils/SystemClock.h
index 892104c..3c59297 100644
--- a/libutils/include/utils/SystemClock.h
+++ b/libutils/include/utils/SystemClock.h
@@ -20,11 +20,18 @@
#include <stdint.h>
#include <sys/types.h>
+// See https://developer.android.com/reference/android/os/SystemClock
+// to learn more about Android's timekeeping facilities.
+
namespace android {
+// Returns milliseconds since boot, not counting time spent in deep sleep.
int64_t uptimeMillis();
+// Returns nanoseconds since boot, not counting time spent in deep sleep.
int64_t uptimeNanos();
+// Returns milliseconds since boot, including time spent in sleep.
int64_t elapsedRealtime();
+// Returns nanoseconds since boot, including time spent in sleep.
int64_t elapsedRealtimeNano();
} // namespace android