Add CPU metrics provider and Add CPU/GPU provider for UKM.

Bug: 907674
Change-Id: I61b88aeac8d2a7ff81d812fa5a267f48203ec7e2
Reviewed-on: https://chromium-review.googlesource.com/c/1381376
Commit-Queue: Nik Bhagat <nikunjb@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618037}
int64_t MetricsLog::GetBuildTime() {
  static int64_t integral_build_time = 0;
  if (!integral_build_time)
    integral_build_time = static_cast<int64_t>(base::GetBuildTime().ToTimeT());
  return integral_build_time;
}

int64_t MetricsLog::GetBuildTime() {
  static int64_t integral_build_time = 0;
  if (!integral_build_time)
    integral_build_time = static_cast<int64_t>(base::GetBuildTime().ToTimeT());
  return integral_build_time;
}
