Finish off SystemClock

PiperOrigin-RevId: 396369189

cpp/platform/impl/windows/BUILD

@@ -17,7 +17,6 @@ cc_library(
     name = "types",
     srcs = [
         "log_message.cc",
-        "system_clock.cc",
     ],
     hdrs = [
         "atomic_boolean.h",
@@ -108,6 +107,7 @@ cc_library(
         "platform.cc",
         "scheduled_executor.cc",
         "submittable_executor.cc",
+        "system_clock.cc",
         "thread_pool.cc",
         "utils.cc",
     ],

cpp/platform/impl/windows/system_clock.cc

@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -21,14 +21,21 @@ namespace location {
 namespace nearby {
 
 // Initialize global system state.
-// TODO(b/184975123): replace with real implementation.
-void SystemClock::Init() {}
+void SystemClock::Init() { }
+
 // Returns current absolute time. It is guaranteed to be monotonic.
-// TODO(b/184975123): replace with real implementation.
-absl::Time SystemClock::ElapsedRealtime() { return absl::UnixEpoch(); }
+absl::Time SystemClock::ElapsedRealtime() {
+  return absl::FromUnixNanos(
+     std::chrono::duration_cast<std::chrono::nanoseconds>(
+         std::chrono::steady_clock::now().time_since_epoch())
+         .count());
+}
+
 // Pauses current thread for the specified duration.
-// TODO(b/184975123): replace with real implementation.
-Exception SystemClock::Sleep(absl::Duration duration) { return Exception{}; }
+Exception SystemClock::Sleep(absl::Duration duration) {
+  absl::SleepFor(duration);
+  return {Exception::kSuccess};
+}
 
 }  // namespace nearby
 }  // namespace location