[Android O] Initialize channels on first launch/upgrade

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

Index: chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsInitializer.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsInitializer.java b/chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsInitializer.java
index 040d7881d4ac5fd996636a08e0de21689e38fc1a..bfece56a43c9a77a906d897bd9477810edaa6f3c 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsInitializer.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/notifications/ChannelsInitializer.java
@@ -35,6 +35,11 @@ public class ChannelsInitializer {
     // Map defined in static inner class so it's only initialized lazily.
     @TargetApi(Build.VERSION_CODES.N) // for NotificationManager.IMPORTANCE_* constants
     private static class PredefinedChannels {
+        /**
+         * The set of predefined channels to be initialized on startup.
+         * {@link ChannelsUpdater#CHANNELS_VERSION} must be incremented every time an entry is

[Peter Beverloo, 2017/04/11 19:08:29]

Maybe consider making this a static member of ChannelsInitializer? This file has
the list of things that have to change when adding or removing a channel, so
it'd localize the needed changes.

[awdf, 2017/04/12 13:58:15]

Done.

+         * modified, removed or added to this map.
+         */
         private static final Map<String, Channel> MAP;
         static {
             Map<String, Channel> map = new HashMap<>();
@@ -68,6 +73,18 @@ public class ChannelsInitializer {
         mNotificationManager = notificationManagerProxy;
     }
 
+    public void initializeStartupChannels() {
+        for (@ChannelId String channelId : PredefinedChannels.MAP.keySet()) {
+            ensureInitialized(channelId);
+        }
+    }
+
+    void deleteAllChannels() {
+        for (String channelId : mNotificationManager.getNotificationChannelIds()) {
+            mNotificationManager.deleteNotificationChannel(channelId);
+        }
+    }
+
     /**
      * Ensures the given channel has been created on the notification manager so a notification
      * can be safely posted to it. This should only be used for channels that are predefined in
@@ -93,7 +110,7 @@ public class ChannelsInitializer {
      */
     public static class Channel {
         @ChannelId
-        final String mId;
+        public final String mId;
         final int mNameResId;
         final int mImportance;
         @ChannelGroupId