Android 屏蔽安全模式+去掉系统安全模式（SAFE MODE）

去除：进入 alps\frameworks\base\core\res\res\values\config.xml

 <string-array translatable="false" name="config_defaultFirstUserRestrictions">
    + <item>no_safe_boot</item>
    </string-array>

frameworks/base/services/core/java/com/android/server/power/ShutdownThread.java

    public static void rebootSafeMode(final Context context, boolean confirm) {
        UserManager um = (UserManager) context.getSystemService(Context.USER_SERVICE);
        if (um.hasUserRestriction(UserManager.DISALLOW_SAFE_BOOT)) {
            return;
        }

        mReboot = true;
        mRebootSafeMode = false;//true
        mRebootHasProgressBar = false;
        mReason = null;
        shutdownInner(context, confirm);
    }

/frameworks/base/services/core/java/com/android/server/wm/WindowManagerService.java

public boolean detectSafeMode() {
        if (!mInputManagerCallback.waitForInputDevicesReady(
                INPUT_DEVICES_READY_FOR_SAFE_MODE_DETECTION_TIMEOUT_MILLIS)) {
            ProtoLog.w(WM_ERROR, "Devices still not ready after waiting %d"
                            + " milliseconds before attempting to detect safe mode.",
                    INPUT_DEVICES_READY_FOR_SAFE_MODE_DETECTION_TIMEOUT_MILLIS);
        }

        if (Settings.Global.getInt(
                mContext.getContentResolver(), Settings.Global.SAFE_BOOT_DISALLOWED, 0) != 0) {
            return false;
        }

        int menuState = mInputManager.getKeyCodeState(-1, InputDevice.SOURCE_ANY,
                KeyEvent.KEYCODE_MENU);
        int sState = mInputManager.getKeyCodeState(-1, InputDevice.SOURCE_ANY, KeyEvent.KEYCODE_S);
        int dpadState = mInputManager.getKeyCodeState(-1, InputDevice.SOURCE_DPAD,
                KeyEvent.KEYCODE_DPAD_CENTER);
        int trackballState = mInputManager.getScanCodeState(-1, InputDevice.SOURCE_TRACKBALL,
                InputManagerService.BTN_MOUSE);
        int volumeDownState = mInputManager.getKeyCodeState(-1, InputDevice.SOURCE_ANY,
                KeyEvent.KEYCODE_VOLUME_DOWN);
        mSafeMode = menuState > 0 || sState > 0 || dpadState > 0 || trackballState > 0
                || volumeDownState > 0;
        try {
            if (SystemProperties.getInt(ShutdownThread.REBOOT_SAFEMODE_PROPERTY, 0) != 0
                    || SystemProperties.getInt(ShutdownThread.RO_SAFEMODE_PROPERTY, 0) != 0) {
                mSafeMode = true;
                SystemProperties.set(ShutdownThread.REBOOT_SAFEMODE_PROPERTY, "");
            }
        } catch (IllegalArgumentException e) {
        }
        if (mSafeMode) {
            // May already be set if (for instance) this process has crashed
            if (SystemProperties.getInt(ShutdownThread.RO_SAFEMODE_PROPERTY, 0) == 0) {
                SystemProperties.set(ShutdownThread.RO_SAFEMODE_PROPERTY, "1");
            }
        } else {
            ProtoLog.i(WM_ERROR, "SAFE MODE not enabled");
        }
        mPolicy.setSafeMode(mSafeMode);
        return false;//mSafeMode
    }