Update description when device allows guest user

If device supports guest user mode, app pinning
recommends guest feature to user.

Test: Rebuilt rom and see correct string in app pinning.
Fix: 151332926
Change-Id: I6c03ecfe075fba2f4dedca18f65893f328e680aa

res/values/strings.xml

@@ -9242,10 +9242,10 @@
         \t\n3.\tTap the app icon at the top of the screen, then tap Pin
     </string>
     <!-- [CHAR LIMIT=none] Screen pinning description -->
-    <string name="screen_pinning_guest_mode_description">
+    <string name="screen_pinning_guest_user_description">
         App pinning allows you to keep the current app in view until you unpin it. This feature can be used, for example, to let a trusted friend play a specific game.
         \n\nWhen an app is pinned, the pinned app may open other apps and personal data may be accessible.
-        \n\nIf you want to securely share your device with someone, try using a guest profile instead.
+        \n\nIf you want to securely share your device with someone, try using a guest user instead.
         \n\nTo use app pinning:
         \t\n1.\tTurn on app pinning
         \t\n2.\tOpen Overview

src/com/android/settings/security/ScreenPinningSettings.java

@@ -22,6 +22,7 @@ import android.content.DialogInterface;
 import android.content.Intent;
 import android.os.Bundle;
 import android.os.UserHandle;
+import android.os.UserManager;
 import android.provider.SearchIndexableResource;
 import android.provider.Settings;
 import android.widget.Switch;
@@ -61,6 +62,7 @@ public class ScreenPinningSettings extends SettingsPreferenceFragment
     private SwitchPreference mUseScreenLock;
     private FooterPreference mFooterPreference;
     private LockPatternUtils mLockPatternUtils;
+    private UserManager mUserManager;
 
     @Override
     public int getMetricsCategory() {
@@ -74,6 +76,7 @@ public class ScreenPinningSettings extends SettingsPreferenceFragment
         final SettingsActivity activity = (SettingsActivity) getActivity();
         activity.setTitle(R.string.screen_pinning_title);
         mLockPatternUtils = new LockPatternUtils(activity);
+        mUserManager = activity.getSystemService(UserManager.class);
 
         addPreferencesFromResource(R.xml.screen_pinning_settings);
         final PreferenceScreen root = getPreferenceScreen();
@@ -224,10 +227,22 @@ public class ScreenPinningSettings extends SettingsPreferenceFragment
             mUseScreenLock.setTitle(getCurrentSecurityTitle());
         } else {
             mFooterPreference.setVisible(true);
+            mFooterPreference.setSummary(getAppPinningContent());
             mUseScreenLock.setVisible(false);
         }
     }
 
+    private boolean isGuestModeSupported() {
+        return UserManager.supportsMultipleUsers()
+                && !mUserManager.hasUserRestriction(UserManager.DISALLOW_USER_SWITCH);
+    }
+
+    private CharSequence getAppPinningContent() {
+        return isGuestModeSupported()
+                ? getActivity().getText(R.string.screen_pinning_guest_user_description)
+                : getActivity().getText(R.string.screen_pinning_description);
+    }
+
     /**
      * For search
      */