Merge "Use push/peek/pop for operations on stack"

        if (!DEBUG_BOOT_TIME) {

            return;

        }

        // Pop the top element without throwing NoSuchElementException

        Pair<String, Long> event = mStartTimes.pollFirst();

        if (event == null) {

        if (mStartTimes.peek() == null) {

            Slog.w(mTag, "traceEnd called more times than traceBegin");

            return;

        }

        Pair<String, Long> event = mStartTimes.pop();

        // Log the duration so it can be parsed by external tools for performance reporting

        Slog.d(mTag, event.first + " took to complete: "

                + (SystemClock.elapsedRealtime() - event.second) + "ms");