Android P开发者选项中的USB调试关闭

根据字符查找到开发者选项的字符是：reset_dashboard_title
packages/apps/Settings/res/xml/system_dashboard_fragment.xml
找到对应system_dashboard_fragment.xml调用的Java文件是：
packages/apps/Settings/src/com/android/settings/system/SystemDashboardFragment.java
进而找到：
packages/apps/Settings/src/com/android/settings/system/DashboardFragmentRegistry.java

     static {
        PARENT_TO_CATEGORY_KEY_MAP = new ArrayMap<>();
        PARENT_TO_CATEGORY_KEY_MAP.put(
                NetworkDashboardFragment.class.getName(), CategoryKey.CATEGORY_NETWORK);
        PARENT_TO_CATEGORY_KEY_MAP.put(ConnectedDeviceDashboardFragment.class.getName(),
                CategoryKey.CATEGORY_CONNECT);
        PARENT_TO_CATEGORY_KEY_MAP.put(AdvancedConnectedDeviceDashboardFragment.class.getName(),
                CategoryKey.CATEGORY_DEVICE);
        PARENT_TO_CATEGORY_KEY_MAP.put(AppAndNotificationDashboardFragment.class.getName(),
                CategoryKey.CATEGORY_APPS);
        PARENT_TO_CATEGORY_KEY_MAP.put(PowerUsageSummary.class.getName(),
                CategoryKey.CATEGORY_BATTERY);
        PARENT_TO_CATEGORY_KEY_MAP.put(DefaultAppSettings.class.getName(),
                CategoryKey.CATEGORY_APPS_DEFAULT);
        PARENT_TO_CATEGORY_KEY_MAP.put(DisplaySettings.class.getName(),
                CategoryKey.CATEGORY_DISPLAY);
        PARENT_TO_CATEGORY_KEY_MAP.put(SoundSettings.class.getName(),
                CategoryKey.CATEGORY_SOUND);
        PARENT_TO_CATEGORY_KEY_MAP.put(StorageDashboardFragment.class.getName(),
                CategoryKey.CATEGORY_STORAGE);
        PARENT_TO_CATEGORY_KEY_MAP.put(SecuritySettings.class.getName(),
                CategoryKey.CATEGORY_SECURITY);
        PARENT_TO_CATEGORY_KEY_MAP.put(AccountDetailDashboardFragment.class.getName(),
                CategoryKey.CATEGORY_ACCOUNT_DETAIL);
        PARENT_TO_CATEGORY_KEY_MAP.put(AccountDashboardFragment.class.getName(),
                CategoryKey.CATEGORY_ACCOUNT);
        PARENT_TO_CATEGORY_KEY_MAP.put(
                SystemDashboardFragment.class.getName(), CategoryKey.CATEGORY_SYSTEM);
        PARENT_TO_CATEGORY_KEY_MAP.put(LanguageAndInputSettings.class.getName(),
                CategoryKey.CATEGORY_SYSTEM_LANGUAGE);
        PARENT_TO_CATEGORY_KEY_MAP.put(DevelopmentSettingsDashboardFragment.class.getName(),
                CategoryKey.CATEGORY_SYSTEM_DEVELOPMENT);
        PARENT_TO_CATEGORY_KEY_MAP.put(ConfigureNotificationSettings.class.getName(),
                CategoryKey.CATEGORY_NOTIFICATIONS);
        PARENT_TO_CATEGORY_KEY_MAP.put(LockscreenDashboardFragment.class.getName(),
                CategoryKey.CATEGORY_SECURITY_LOCKSCREEN);
        PARENT_TO_CATEGORY_KEY_MAP.put(ZenModeSettings.class.getName(),
                CategoryKey.CATEGORY_DO_NOT_DISTURB);
        PARENT_TO_CATEGORY_KEY_MAP.put(GestureSettings.class.getName(),
            CategoryKey.CATEGORY_GESTURES);
        PARENT_TO_CATEGORY_KEY_MAP.put(NightDisplaySettings.class.getName(),
            CategoryKey.CATEGORY_NIGHT_DISPLAY);

        CATEGORY_KEY_TO_PARENT_MAP = new ArrayMap<>(PARENT_TO_CATEGORY_KEY_MAP.size());

        for (Map.Entry<String, String> parentToKey : PARENT_TO_CATEGORY_KEY_MAP.entrySet()) {
            CATEGORY_KEY_TO_PARENT_MAP.put(parentToKey.getValue(), parentToKey.getKey());
        }
    }

以上见名知意，可以查看到DevelopmentSettingsDashboardFragment.java即为开发者选项的文件。
进入菜单时候初始化是否是开发者模式：

 @Override
    public void onActivityCreated(Bundle icicle) {
        super.onActivityCreated(icicle);
        // Apply page-level restrictions
        setIfOnlyAvailableForAdmins(true);
        if (isUiRestricted() || !Utils.isDeviceProvisioned(getActivity())) {
            // Block access to developer options if the user is not the owner, if user policy
            // restricts it, or if the device has not been provisioned
            mIsAvailable = false;
            // Show error message
            if (!isUiRestrictedByOnlyAdmin()) {
                getEmptyTextView().setText(R.string.development_settings_not_available);
            }
            getPreferenceScreen().removeAll();
            return;
        }
        // Set up master switch
        mSwitchBar = ((SettingsActivity) getActivity()).getSwitchBar();
        mSwitchBarController = new DevelopmentSwitchBarController(
                this /* DevelopmentSettings */, mSwitchBar, mIsAvailable, getLifecycle());
        mSwitchBar.show();

        // Restore UI state based on whether developer options is enabled
        if (DevelopmentSettingsEnabler.isDevelopmentSettingsEnabled(getContext())) {
            enableDeveloperOptions();
        } else {
            disableDeveloperOptions();
        }
    }
 private void enableDeveloperOptions() {
        if (Utils.isMonkeyRunning()) {
            return;
        }
        DevelopmentSettingsEnabler.setDevelopmentSettingsEnabled(getContext(), true);
        for (AbstractPreferenceController controller : mPreferenceControllers) {
            if (controller instanceof DeveloperOptionsPreferenceController) {
                ((DeveloperOptionsPreferenceController) controller).onDeveloperOptionsEnabled();
            }
        }
    }

    private void disableDeveloperOptions() {
        if (Utils.isMonkeyRunning()) {
            return;
        }
        DevelopmentSettingsEnabler.setDevelopmentSettingsEnabled(getContext(), false);
        final SystemPropPoker poker = SystemPropPoker.getInstance();
        poker.blockPokes();
        for (AbstractPreferenceController controller : mPreferenceControllers) {
            if (controller instanceof DeveloperOptionsPreferenceController) {
                ((DeveloperOptionsPreferenceController) controller)
                        .onDeveloperOptionsDisabled();
            }
        }
        poker.unblockPokes();
        poker.poke();
    }

DevelopmentSettingsEnabler.java文件中：
判断开发者模式是否开启:

      public static final String DEVELOPMENT_SETTINGS_CHANGED_ACTION =
            "com.android.settingslib.development.DevelopmentSettingsEnabler.SETTINGS_CHANGED";

    private DevelopmentSettingsEnabler() {
    }

    public static void setDevelopmentSettingsEnabled(Context context, boolean enable) {
        Settings.Global.putInt(context.getContentResolver(),
                Settings.Global.DEVELOPMENT_SETTINGS_ENABLED, enable ? 1 : 0);
        LocalBroadcastManager.getInstance(context)
                .sendBroadcast(new Intent(DEVELOPMENT_SETTINGS_CHANGED_ACTION));
    }

    public static boolean isDevelopmentSettingsEnabled(Context context) {
        final UserManager um = (UserManager) context.getSystemService(Context.USER_SERVICE);
        final boolean settingEnabled = Settings.Global.getInt(context.getContentResolver(),
                Settings.Global.DEVELOPMENT_SETTINGS_ENABLED,
                Build.TYPE.equals("eng") ? 1 : 0) != 0;
        final boolean hasRestriction = um.hasUserRestriction(
                UserManager.DISALLOW_DEBUGGING_FEATURES);
        final boolean isAdminOrDemo = um.isAdminUser() || um.isDemoUser();
        return isAdminOrDemo && !hasRestriction && settingEnabled;
    }

对应的布局文件是：packages/apps/Settings/res/xml/development_settings.xml

<PreferenceCategory
        android:key="debug_debugging_category"
        android:title="@string/debug_debugging_category"
        android:order="200">

        <SwitchPreference
            android:key="enable_adb"
            android:title="@string/enable_adb"
            android:summary="@string/enable_adb_summary" />

        <Preference android:key="clear_adb_keys"
                    android:title="@string/clear_adb_keys" />

        <SwitchPreference
            android:key="enable_terminal"
            android:title="@string/enable_terminal_title"
            android:summary="@string/enable_terminal_summary" />
....省略较多代码

其对应的实现位于：
frameworks/base/packages/SettingsLib/src/com/android/settingslib/development/AbstractEnableAdbPreferenceController.java
对应ADB的开关如下：

    private boolean isAdbEnabled() {
        final ContentResolver cr = mContext.getContentResolver();
        return Settings.Global.getInt(cr, Settings.Global.ADB_ENABLED, ADB_SETTING_OFF)
                != ADB_SETTING_OFF;
    }

然后在设置中查找对应的默认参数即可。
frameworks/base/packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java

  private void loadSecureSettings(SQLiteDatabase db) {
        SQLiteStatement stmt = null;
        try {
            stmt = db.compileStatement("INSERT OR IGNORE INTO secure(name,value)"
                    + " VALUES(?,?);");

            loadStringSetting(stmt, Settings.Secure.LOCATION_PROVIDERS_ALLOWED,
                    R.string.def_location_providers_allowed);

            // Don't do this.  The SystemServer will initialize ADB_ENABLED from a
            // persistent system property instead.
            //loadSetting(stmt, Settings.Secure.ADB_ENABLED, 0);

            // Allow mock locations default, based on build
            loadSetting(stmt, Settings.Secure.ALLOW_MOCK_LOCATION,
                    "1".equals(SystemProperties.get("ro.allow.mock.location")) ? 1 : 0);
 ....//省略较多代码

根据以上注释重新查找persistent 中属性的位置；
frameworks/base/services/usb/java/com/android/server/usb/UsbDeviceManager.java

UsbHandler(Looper looper, Context context, UsbDeviceManager deviceManager,
                UsbDebuggingManager debuggingManager, UsbAlsaManager alsaManager,
                UsbSettingsManager settingsManager) {
            super(looper);
            mContext = context;
            mDebuggingManager = debuggingManager;
            mUsbDeviceManager = deviceManager;
            mUsbAlsaManager = alsaManager;
            mSettingsManager = settingsManager;
            mContentResolver = context.getContentResolver();

            mCurrentUser = ActivityManager.getCurrentUser();
            mScreenLocked = true;

            /*
             * Use the normal bootmode persistent prop to maintain state of adb across
             * all boot modes.
             */
            mAdbEnabled = UsbHandlerLegacy.containsFunction(getSystemProperty(
                    USB_PERSISTENT_CONFIG_PROPERTY, ""), UsbManager.USB_FUNCTION_ADB);

            mSettings = getPinnedSharedPrefs(mContext);
            if (mSettings == null) {
                Slog.e(TAG, "Couldn't load shared preferences");
            } else {
                mScreenUnlockedFunctions = UsbManager.usbFunctionsFromString(
                        mSettings.getString(
                                String.format(Locale.ENGLISH, UNLOCKED_CONFIG_PREF, mCurrentUser),
                                ""));
            }

            // We do not show the USB notification if the primary volume supports mass storage.
            // The legacy mass storage UI will be used instead.
            final StorageManager storageManager = StorageManager.from(mContext);
            final StorageVolume primary = storageManager.getPrimaryVolume();

            boolean massStorageSupported = primary != null && primary.allowMassStorage();
            mUseUsbNotification = !massStorageSupported && mContext.getResources().getBoolean(
                    com.android.internal.R.bool.config_usbChargingMessage);
        }

查看具体的：USB_PERSISTENT_CONFIG_PROPERTY的属性值：
protected static final String USB_PERSISTENT_CONFIG_PROPERTY = “persist.sys.usb.config”;

继续查看有文件：
build/make/tools/post_process_props.py

# Put the modifications that you need to make into the /system/etc/prop.default into this
# function. The prop object has get(name) and put(name,value) methods.
def mangle_default_prop(prop):
  # If ro.debuggable is 1, then enable adb on USB by default
  # (this is for userdebug builds)
  if prop.get("ro.debuggable") == "1":
    val = prop.get("persist.sys.usb.config")
    if "adb" not in val:
      if val == "":
        val = "diag,serial_cdev,rmnet,adb"
      else:
        val = val + ",adb"
      prop.put("persist.sys.usb.config", val)
  # UsbDeviceManager expects a value here.  If it doesn't get it, it will
  # default to "adb". That might not the right policy there, but it's better
  # to be explicit.
  if not prop.get("persist.sys.usb.config"):
    prop.put("persist.sys.usb.config", "none");

如果ro.debuggable 为1 则赋值，否则不操作；
对应ro.debuggable的赋值过程见 build/make/core/main.mk

user_variant := $(filter user userdebug,$(TARGET_BUILD_VARIANT))
enable_target_debugging := true
tags_to_install :=
ifneq (,$(user_variant))
  # Target is secure in user builds.
  ADDITIONAL_DEFAULT_PROPERTIES += ro.secure=1
  ADDITIONAL_DEFAULT_PROPERTIES += security.perf_harden=1

  ifeq ($(user_variant),user)
    ADDITIONAL_DEFAULT_PROPERTIES += ro.adb.secure=1
  endif

  ifeq ($(user_variant),userdebug)
    # Pick up some extra useful tools
    tags_to_install += debug
  else
    # Disable debugging in plain user builds.
    enable_target_debugging :=
  endif

  # Disallow mock locations by default for user builds
  ADDITIONAL_DEFAULT_PROPERTIES += ro.allow.mock.location=0

else # !user_variant
  # Turn on checkjni for non-user builds.
  ADDITIONAL_BUILD_PROPERTIES += ro.kernel.android.checkjni=0
  # Set device insecure for non-user builds.
  ADDITIONAL_DEFAULT_PROPERTIES += ro.secure=0
  # Allow mock locations by default for non user builds
  ADDITIONAL_DEFAULT_PROPERTIES += ro.allow.mock.location=1
endif # !user_variant

ifeq (true,$(strip $(enable_target_debugging)))
  # Target is more debuggable and adbd is on by default
  ifeq ($(user_variant),user)
     ADDITIONAL_DEFAULT_PROPERTIES += ro.debuggable=0
  else
     ADDITIONAL_DEFAULT_PROPERTIES += ro.debuggable=1
  endif
  # Enable Dalvik lock contention logging.
  ADDITIONAL_BUILD_PROPERTIES += dalvik.vm.lockprof.threshold=500
  # Include the debugging/testing OTA keys in this build.
  INCLUDE_TEST_OTA_KEYS := true
else # !enable_target_debugging
  # Target is less debuggable and adbd is off by default
  ADDITIONAL_DEFAULT_PROPERTIES += ro.debuggable=0
endif # !enable_target_debugging

此处应该就是默认是否debug的位置；
如果以上修改依然不能成功，则需要判断开关的控制是否被拦截；具体文件可能是：
device/qcom/common / rootdir/etc/init.qcom.usb.sh

#
# Override USB default composition
#
# If USB persist config not set, set default configuration
if [ "$(getprop persist.vendor.usb.config)" == "" -a \
	"$(getprop init.svc.vendor.usb-gadget-hal-1-0)" != "running" ]; then
    if [ "$esoc_name" != "" ]; then
	  setprop persist.vendor.usb.config diag,diag_mdm,qdss,qdss_mdm,serial_cdev,dpl,rmnet,adb
    else
	  case "$(getprop ro.baseband)" in
	      "apq")
	          setprop persist.vendor.usb.config diag,adb
	      ;;
	      *)
	      case "$soc_hwplatform" in
	          "Dragon" | "SBC")
	              setprop persist.vendor.usb.config diag,adb
	          ;;
                  *)
		  case "$soc_machine" in
		    "SA")
	              setprop persist.vendor.usb.config diag,adb
		    ;;
		    *)
	            case "$target" in
	              "msm8909")
		          setprop persist.vendor.usb.config diag,serial_smd,rmnet_qti_bam,adb
		      ;;
	              "msm8937")
			    if [ -d /config/usb_gadget ]; then
				       setprop persist.vendor.usb.config diag,serial_cdev,rmnet,dpl,adb
			    else
			               case "$soc_id" in
				               "313" | "320")
				                  setprop persist.vendor.usb.config diag,serial_smd,rmnet_ipa,adb
				               ;;
				               *)
				                  setprop persist.vendor.usb.config diag,serial_smd,rmnet_qti_bam,adb
				               ;;
			               esac
			    fi
		      ;;
	              "msm8953")
			      if [ -d /config/usb_gadget ]; then
				      setprop persist.vendor.usb.config diag,serial_cdev,rmnet,dpl,adb
			      else
				      setprop persist.vendor.usb.config diag,serial_smd,rmnet_ipa,adb
			      fi
		      ;;
	              "msm8996")
			      if [ -d /config/usb_gadget ]; then
				      setprop persist.vendor.usb.config diag,serial_cdev,rmnet,adb
			      else
				      setprop persist.vendor.usb.config diag,serial_cdev,serial_tty,rmnet_ipa,mass_storage,adb
			      fi
		      ;;
	              "msm8998" | "sdm660" | "apq8098_latv")
		          setprop persist.vendor.usb.config diag,serial_cdev,rmnet,adb
		      ;;
	              "sdm845" | "sdm710")
		          setprop persist.vendor.usb.config diag,serial_cdev,rmnet,dpl,adb
		      ;;
	              "msmnile" | "sm6150" | "trinket")
			  setprop persist.vendor.usb.config diag,serial_cdev,rmnet,dpl,qdss,adb
		      ;;
	              *)
		          setprop persist.vendor.usb.config diag,adb
		      ;;
                    esac
		    ;;
		  esac
	          ;;
	      esac
	      ;;
	  esac
      fi
fi

按照以上配置屏蔽即可。