Add suppressor text in SummaryProvider of Sound when it exists.

When suppressor exists for the sound effect, the sound summary
should show "muted by ...", not the "Ring volume at ..."

Bug: 31461022
Test: make -j40 RunSettingsRoboTests
Change-Id: I5d6895a7a330c993aac40bdca3bb1c79f8b7fbfe

src/com/android/settings/notification/SuppressorHelper.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2016 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.notification;
+
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.pm.PackageManager;
+import android.content.pm.ServiceInfo;
+import android.support.annotation.VisibleForTesting;
+import android.util.Log;
+
+public class SuppressorHelper {
+    private static final String TAG = "SuppressorHelper";
+
+    public static String getSuppressionText(Context context, ComponentName suppressor) {
+        return suppressor != null ?
+                context.getString(com.android.internal.R.string.muted_by,
+                        getSuppressorCaption(context, suppressor)) : null;
+    }
+
+    @VisibleForTesting
+    static String getSuppressorCaption(Context context, ComponentName suppressor) {
+        final PackageManager pm = context.getPackageManager();
+        try {
+            final ServiceInfo info = pm.getServiceInfo(suppressor, 0);
+            if (info != null) {
+                final CharSequence seq = info.loadLabel(pm);
+                if (seq != null) {
+                    final String str = seq.toString().trim();
+                    if (str.length() > 0) {
+                        return str;
+                    }
+                }
+            }
+        } catch (Throwable e) {
+            Log.w(TAG, "Error loading suppressor caption", e);
+        }
+        return suppressor.getPackageName();
+    }
+
+}