Ask user to reboot when enabling freeform and desktop mode

The introduction of FreeformTaskListener in WM shell requires a reboot
after enabling freeform support fully. Let's add a dialog explaining the
requirement and ask user to reboot the device.

Enabling desktop mode also requires a reboot to take effect, so this CL
also adds the support to it.

There is also a cancel button to dismiss the dialog without a reboot,
just in case users need to hold off the reboot for any reason.

Bug: 215437867
Test: Pressing OK reboots the device. Pressing Cancel dismisses the
dialog.
Test: atest SettingsRoboTests:FreeformWindowsPreferenceControllerTest
Test: atest SettingsRoboTests:DesktopModePreferenceControllerTest

Change-Id: I553237a29751f73afa9fd4066241a19740872f6f

src/com/android/settings/development/FreeformWindowsPreferenceController.java

@@ -17,6 +17,7 @@
 package com.android.settings.development;
 
 import android.content.Context;
+import android.content.Intent;
 import android.os.Build;
 import android.provider.Settings;
 
@@ -24,11 +25,13 @@ import androidx.annotation.VisibleForTesting;
 import androidx.preference.Preference;
 import androidx.preference.SwitchPreference;
 
+import com.android.settings.R;
 import com.android.settings.core.PreferenceControllerMixin;
 import com.android.settingslib.development.DeveloperOptionsPreferenceController;
 
 public class FreeformWindowsPreferenceController extends DeveloperOptionsPreferenceController
-        implements Preference.OnPreferenceChangeListener, PreferenceControllerMixin {
+        implements Preference.OnPreferenceChangeListener, PreferenceControllerMixin,
+        RebootConfirmationDialogHost {
 
     private static final String ENABLE_FREEFORM_SUPPORT_KEY = "enable_freeform_support";
 
@@ -37,8 +40,12 @@ public class FreeformWindowsPreferenceController extends DeveloperOptionsPrefere
     @VisibleForTesting
     static final int SETTING_VALUE_ON = 1;
 
-    public FreeformWindowsPreferenceController(Context context) {
+    private final DevelopmentSettingsDashboardFragment mFragment;
+
+    public FreeformWindowsPreferenceController(
+            Context context, DevelopmentSettingsDashboardFragment fragment) {
         super(context);
+        mFragment = fragment;
     }
 
     @Override
@@ -52,6 +59,10 @@ public class FreeformWindowsPreferenceController extends DeveloperOptionsPrefere
         Settings.Global.putInt(mContext.getContentResolver(),
                 Settings.Global.DEVELOPMENT_ENABLE_FREEFORM_WINDOWS_SUPPORT,
                 isEnabled ? SETTING_VALUE_ON : SETTING_VALUE_OFF);
+        if (isEnabled) {
+            RebootConfirmationDialogFragment.show(
+                    mFragment, R.string.reboot_dialog_enable_freeform_support, this);
+        }
         return true;
     }
 
@@ -70,6 +81,12 @@ public class FreeformWindowsPreferenceController extends DeveloperOptionsPrefere
         ((SwitchPreference) mPreference).setChecked(false);
     }
 
+    @Override
+    public void onRebootConfirmed() {
+        final Intent intent = new Intent(Intent.ACTION_REBOOT);
+        mContext.startActivity(intent);
+    }
+
     @VisibleForTesting
     String getBuildType() {
         return Build.TYPE;