Hide SettingsSlice provider

Explicitly set the Settings SliceBroadcastReceiver to
be non-exported and remove the intent-filter.

Add a second provider: SliceRelayReceiver to receive
broadcasts from SysUI to alert Settings to potential
changes to bound Settings Slices. The new receiver is
exported, but only notifies changes to Settings, and
doesn't make any changes itself.

Change-Id: I80d070f7636614135ebe4f57a16f12a3eb6dee81
Fixes: 111330641
Test: boot, robolectric, Slicebrowser

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package com.android.settings.slices;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.net.Uri;
+import android.text.TextUtils;
+import com.android.settingslib.SliceBroadcastRelay;
+
+/**
+ * Receives broadcasts to notify that Settings Slices are potentially stale.
+ */
+public class SliceRelayReceiver extends BroadcastReceiver {
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        final String uriString = intent.getStringExtra(SliceBroadcastRelay.EXTRA_URI);
+        if (!TextUtils.isEmpty(uriString)) {
+            final Uri uri = Uri.parse(uriString);
+            context.getContentResolver().notifyChange(uri, null /* observer */);
+        }
+    }
+}