Add isSliceable API to BasePrefController

Only support explicitly approved Settings Slices,
dictated by controllers which return true for the new
method isSliceable.

Updating the supported settings to a whitelist means that
the method to return all available slices must be updated,
and checking slicability when we index slices.

Test: robotests
Bug: 79779103
Change-Id: Ib2b9690cdd0036b5cc4a1cb846c52bce7c824ab9

src/com/android/settings/slices/SettingsSliceProvider.java

@@ -23,9 +23,11 @@ import android.content.ContentResolver;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.net.Uri;
+import android.provider.Settings;
 import android.provider.SettingsSlicesContract;
 import android.text.TextUtils;
 import android.util.ArraySet;
+import android.util.KeyValueListParser;
 import android.util.Log;
 import android.util.Pair;
 
@@ -42,6 +44,7 @@ import java.net.URISyntaxException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -115,10 +118,13 @@ public class SettingsSliceProvider extends SliceProvider {
     @VisibleForTesting
     Map<Uri, SliceData> mSliceDataCache;
 
+    private final KeyValueListParser mParser;
+
     final Set<Uri> mRegisteredUris = new ArraySet<>();
 
     public SettingsSliceProvider() {
         super(READ_SEARCH_INDEXABLES);
+        mParser = new KeyValueListParser(',');
     }
 
     @Override
@@ -352,4 +358,32 @@ public class SettingsSliceProvider extends SliceProvider {
         SliceBroadcastRelay.registerReceiver(getContext(), sliceUri, SliceBroadcastReceiver.class,
                 intentFilter);
     }
+
+    @VisibleForTesting
+    Set<String> getBlockedKeys() {
+        final String value = Settings.Global.getString(getContext().getContentResolver(),
+                Settings.Global.BLOCKED_SLICES);
+        final Set<String> set = new ArraySet<>();
+
+        try {
+            mParser.setString(value);
+        } catch (IllegalArgumentException e) {
+            Log.e(TAG, "Bad Settings Slices Whitelist flags", e);
+            return set;
+        }
+
+        final String[] parsedValues = parseStringArray(value);
+        Collections.addAll(set, parsedValues);
+        return set;
+    }
+
+    private String[] parseStringArray(String value) {
+        if (value != null) {
+            String[] parts = value.split(":");
+            if (parts.length > 0) {
+                return parts;
+            }
+        }
+        return new String[0];
+    }
 }