Fix a regression in enabling unknown sources toggle

In Security Settings, allow unknown sources to be
toggled for primary and secondary users unless it
is a restricted profile or there is a device policy
restriction to disallow installing apps or installing
from unknown sources.

Bug: 18277370
Change-Id: I9f0b6cd603c4c8deb77d36af1b82cace43ba195f
diff --git a/src/com/android/settings/SecuritySettings.java b/src/com/android/settings/SecuritySettings.java
index aa27e3b..ab08553 100644
--- a/src/com/android/settings/SecuritySettings.java
+++ b/src/com/android/settings/SecuritySettings.java
@@ -336,7 +336,8 @@
                 KEY_TOGGLE_INSTALL_APPLICATIONS);
         mToggleAppInstallation.setChecked(isNonMarketAppsAllowed());
         // Side loading of apps.
-        mToggleAppInstallation.setEnabled(mIsPrimary);
+        // Disable for restricted profiles. For others, check if policy disallows it.
+        mToggleAppInstallation.setEnabled(!um.getUserInfo(UserHandle.myUserId()).isRestricted());
         if (um.hasUserRestriction(UserManager.DISALLOW_INSTALL_UNKNOWN_SOURCES)
                 || um.hasUserRestriction(UserManager.DISALLOW_INSTALL_APPS)) {
             mToggleAppInstallation.setEnabled(false);