[Android O] Refactor channel definitions into new class

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 afd4d32337f028750832e7c60e551eb28b295299..526295fdd6e8206b691920b2edc36338ea76d3c0 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
@@ -4,100 +4,26 @@
 
 package org.chromium.chrome.browser.notifications;
 
-import android.annotation.TargetApi;
-import android.app.NotificationManager;
-import android.os.Build;
-import android.support.annotation.StringDef;
-
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
-
 /**
  * Initializes our notification channels.
  */
 public class ChannelsInitializer {
-    /**
-     * Version number identifying the current set of channels. This must be incremented whenever
-     * any channels are added or removed from the set of channels created in
-     * {@link ChannelsInitializer#initializeStartupChannels()}
-     */
-    static final int CHANNELS_VERSION = 0;
-
-    // To define a new channel, add the channel ID to this StringDef and add a new entry to
-    // PredefinedChannels.MAP below with the appropriate channel parameters.
-    @StringDef({CHANNEL_ID_BROWSER, CHANNEL_ID_DOWNLOADS, CHANNEL_ID_INCOGNITO, CHANNEL_ID_MEDIA,
-            CHANNEL_ID_SITES})
-    @Retention(RetentionPolicy.SOURCE)
-    public @interface ChannelId {}
-    public static final String CHANNEL_ID_BROWSER = "browser";
-    public static final String CHANNEL_ID_DOWNLOADS = "downloads";
-    public static final String CHANNEL_ID_INCOGNITO = "incognito";
-    public static final String CHANNEL_ID_MEDIA = "media";
-    public static final String CHANNEL_ID_SITES = "sites";
-
-    @StringDef({CHANNEL_GROUP_ID_GENERAL})
-    @Retention(RetentionPolicy.SOURCE)
-    private @interface ChannelGroupId {}
-    static final String CHANNEL_GROUP_ID_GENERAL = "general";
-
-    // 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. CHANNELS_VERSION must be
-         * incremented every time an entry is modified, removed or added to this map.
-         */
-        private static final Map<String, Channel> MAP;
-        static {
-            Map<String, Channel> map = new HashMap<>();
-            map.put(CHANNEL_ID_BROWSER,
-                    new Channel(CHANNEL_ID_BROWSER,
-                            org.chromium.chrome.R.string.notification_category_browser,
-                            NotificationManager.IMPORTANCE_LOW, CHANNEL_GROUP_ID_GENERAL));
-            map.put(CHANNEL_ID_DOWNLOADS,
-                    new Channel(CHANNEL_ID_DOWNLOADS,
-                            org.chromium.chrome.R.string.notification_category_downloads,
-                            NotificationManager.IMPORTANCE_LOW, CHANNEL_GROUP_ID_GENERAL));
-            map.put(CHANNEL_ID_INCOGNITO,
-                    new Channel(CHANNEL_ID_INCOGNITO,
-                            org.chromium.chrome.R.string.notification_category_incognito,
-                            NotificationManager.IMPORTANCE_LOW, CHANNEL_GROUP_ID_GENERAL));
-            map.put(CHANNEL_ID_MEDIA,
-                    new Channel(CHANNEL_ID_MEDIA,
-                            org.chromium.chrome.R.string.notification_category_media,
-                            NotificationManager.IMPORTANCE_LOW, CHANNEL_GROUP_ID_GENERAL));
-            map.put(CHANNEL_ID_SITES,
-                    new Channel(CHANNEL_ID_SITES,
-                            org.chromium.chrome.R.string.notification_category_sites,
-                            NotificationManager.IMPORTANCE_DEFAULT, CHANNEL_GROUP_ID_GENERAL));
-            MAP = Collections.unmodifiableMap(map);
-        }
-    }
-
-    // Map defined in static inner class so it's only initialized lazily.
-    private static class PredefinedChannelGroups {
-        private static final Map<String, ChannelGroup> MAP;
-        static {
-            Map<String, ChannelGroup> map = new HashMap<>();
-            map.put(CHANNEL_GROUP_ID_GENERAL,
-                    new ChannelGroup(CHANNEL_GROUP_ID_GENERAL,
-                            org.chromium.chrome.R.string.notification_category_group_general));
-            MAP = Collections.unmodifiableMap(map);
-        }
-    }
 
     private final NotificationManagerProxy mNotificationManager;
+    private final ChannelDefinitions mChannelDefinitions;
 
-    public ChannelsInitializer(NotificationManagerProxy notificationManagerProxy) {
+    public ChannelsInitializer(NotificationManagerProxy notificationManagerProxy,
+            ChannelDefinitions channelDefinitions) {
         mNotificationManager = notificationManagerProxy;
+        mChannelDefinitions = channelDefinitions;
     }
 
+    /**
+     * Creates all the channels on the notification manager that we want to appear in our
+     * channel settings from first launch onwards.
+     */
     public void initializeStartupChannels() {
-        // CHANNELS_VERSION must be incremented if the set of channels initialized here changes.
-        for (@ChannelId String channelId : PredefinedChannels.MAP.keySet()) {
+        for (String channelId : mChannelDefinitions.getStartupChannelIds()) {
             ensureInitialized(channelId);
         }
     }
@@ -111,54 +37,21 @@ public class ChannelsInitializer {
     /**
      * 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
-     * ChannelsInitializer.
+     * {@link ChannelDefinitions.PredefinedChannels}.
      *
      * Calling this is a (potentially lengthy) no-op if the channel has already been created.
      *
      * @param channelId The ID of the channel to be initialized.
      */
-    public void ensureInitialized(@ChannelId String channelId) {
-        if (!PredefinedChannels.MAP.containsKey(channelId)) {
+    public void ensureInitialized(@ChannelDefinitions.ChannelId String channelId) {
+        ChannelDefinitions.Channel channel = mChannelDefinitions.getChannelFromId(channelId);
+        if (channel == null) {
             throw new IllegalStateException("Could not initialize channel: " + channelId);
         }
-        Channel channel = PredefinedChannels.MAP.get(channelId);
         // Channel group must be created before the channel.
         mNotificationManager.createNotificationChannelGroup(
-                PredefinedChannelGroups.MAP.get(channel.mGroupId));
+                mChannelDefinitions.getChannelGroupFromId(channel));
         mNotificationManager.createNotificationChannel(channel);
     }
 
-    /**
-     * Helper class containing notification channel properties.
-     */
-    public static class Channel {
-        @ChannelId
-        public final String mId;
-        final int mNameResId;
-        final int mImportance;
-        @ChannelGroupId
-        final String mGroupId;
-
-        Channel(@ChannelId String id, int nameResId, int importance,
-                @ChannelGroupId String groupId) {
-            this.mId = id;
-            this.mNameResId = nameResId;
-            this.mImportance = importance;
-            this.mGroupId = groupId;
-        }
-    }
-
-    /**
-     * Helper class containing notification channel group properties.
-     */
-    public static class ChannelGroup {
-        @ChannelGroupId
-        final String mId;
-        final int mNameResId;
-
-        ChannelGroup(@ChannelGroupId String id, int nameResId) {
-            this.mId = id;
-            this.mNameResId = nameResId;
-        }
-    }
 }