[Android O] Only delete legacy notification channels on upgrade

chrome/android/junit/src/org/chromium/chrome/browser/notifications/ChannelDefinitionsTest.java

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.notifications;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.everyItem;
+import static org.hamcrest.Matchers.isIn;
+import static org.hamcrest.Matchers.not;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.BlockJUnit4ClassRunner;
+
+/**
+ * Java unit tests for ChannelDefinitions.
+ */
+@RunWith(BlockJUnit4ClassRunner.class)
+public class ChannelDefinitionsTest {
+    @Test
+    public void testNoOverlapBetweenStartupAndLegacyChannelIds() throws Exception {
+        ChannelDefinitions channelDefinitions = new ChannelDefinitions();
+        assertThat(channelDefinitions.getStartupChannelIds(),
+                everyItem(not(isIn(channelDefinitions.getLegacyChannelIds()))));
+    }
+}