【Android N 7.1.1】 屏幕亮和灭的处理地方

frameworks/base/services/core/java/com/android/server/display/DisplayPowerController.java

    private void updatePowerState() {
        if (true) {  //按power按键，屏幕不会灭了
            return;
        }

        ....

　}

    private void blockScreenOn() {
        if (mPendingScreenOnUnblocker == null) {
            Trace.asyncTraceBegin(Trace.TRACE_TAG_POWER, SCREEN_ON_BLOCKED_TRACE_NAME, 0);
            mPendingScreenOnUnblocker = new ScreenOnUnblocker();
            mScreenOnBlockStartRealTime = SystemClock.elapsedRealtime();
            Slog.i(TAG, "Blocking screen on until initial contents have been drawn.");
        }
    }

    private void unblockScreenOn() {
        if (mPendingScreenOnUnblocker != null) {
            mPendingScreenOnUnblocker = null;
            long delay = SystemClock.elapsedRealtime() - mScreenOnBlockStartRealTime;
            Slog.i(TAG, "Unblocked screen on after " + delay + " ms");
            Trace.asyncTraceEnd(Trace.TRACE_TAG_POWER, SCREEN_ON_BLOCKED_TRACE_NAME, 0);
        }
    }