Disable content protection settings if no service

Bug: 308613762
Test: Unit tests and manual end-to-end
Change-Id: I0cc1ff1a260a7e14537036497a155135b7e2f0a9

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

@@ -17,9 +17,14 @@ package com.android.settings.security;
 
 import static android.view.contentprotection.flags.Flags.settingUiEnabled;
 
+import static com.android.internal.R.string.config_defaultContentProtectionService;
+
+import android.content.ComponentName;
 import android.content.Context;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 
 import com.android.settings.core.BasePreferenceController;
 
@@ -31,7 +36,24 @@ public class ContentProtectionPreferenceController extends BasePreferenceControl
 
     @Override
     public int getAvailabilityStatus() {
-      // TODO(b/306565942): Add a resource value check.
-      return settingUiEnabled() ? AVAILABLE : UNSUPPORTED_ON_DEVICE;
+        if (!settingUiEnabled() || getContentProtectionServiceComponentName() == null) {
+            return UNSUPPORTED_ON_DEVICE;
+        }
+        return AVAILABLE;
+    }
+
+    @VisibleForTesting
+    @Nullable
+    protected String getContentProtectionServiceFlatComponentName() {
+        return mContext.getString(config_defaultContentProtectionService);
+    }
+
+    @Nullable
+    private ComponentName getContentProtectionServiceComponentName() {
+        String flatComponentName = getContentProtectionServiceFlatComponentName();
+        if (flatComponentName == null) {
+            return null;
+        }
+        return ComponentName.unflattenFromString(flatComponentName);
     }
 }