[Android O] Initialize notification channels on OS upgrade

chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsUpdater.java

Index: chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsUpdater.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsUpdater.java b/chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsUpdater.java
index 8a7a1a95eceb3acdf8c70d5c9811495737877357..eb4b2567aaa8749d69285c478aaaea079c8ca63e 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsUpdater.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsUpdater.java
@@ -5,8 +5,10 @@
 package org.chromium.chrome.browser.notifications;
 
 import android.app.NotificationManager;
+import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.SharedPreferences;
+import android.os.AsyncTask;
 
 import org.chromium.base.BuildInfo;
 import org.chromium.base.ContextUtils;
@@ -56,6 +58,18 @@ public class ChannelsUpdater {
                 && mSharedPreferences.getInt(CHANNELS_VERSION_KEY, -1) != mChannelsVersion;
     }
 
+    public void updateChannelsInBackground(final BroadcastReceiver.PendingResult result) {
+        new AsyncTask<Void, Void, Void>() {
+            @Override
+            protected Void doInBackground(Void... params) {
+                updateChannels();
+                result.finish();
+                return null;
+            }
+        }
+                .executeOnExecutor(AsyncTask.SERIAL_EXECUTOR);
+    }
+
     public void updateChannels() {
         if (!mIsAtLeastO) return;
         assert mChannelsInitializer != null;