[Android O] Refactor channel initialization

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

Index: chrome/android/java/src/org/chromium/chrome/browser/notifications/NotificationBuilderForO.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/notifications/NotificationBuilderForO.java b/chrome/android/java/src/org/chromium/chrome/browser/notifications/NotificationBuilderForO.java
index 2daa053716ff1592fcba69f894c8d72d35d86602..b207b3a5e00d6b7df3b0e73f7d81530baa83e409 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/notifications/NotificationBuilderForO.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/notifications/NotificationBuilderForO.java
@@ -6,13 +6,11 @@ package org.chromium.chrome.browser.notifications;
 
 import android.annotation.TargetApi;
 import android.app.Notification;
-import android.app.NotificationManager;
 import android.content.Context;
 
 import org.chromium.base.BuildInfo;
 import org.chromium.base.Log;
 
-import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 
@@ -23,77 +21,17 @@ import java.lang.reflect.Method;
 public class NotificationBuilderForO extends NotificationBuilder {
     private static final String TAG = "NotifBuilderForO";
 
-    public NotificationBuilderForO(Context context, String channelId, String channelName,
-            String channelGroupId, String channelGroupName) {
+    public NotificationBuilderForO(Context context, @ChannelsInitializer.ChannelId String channelId,
+            ChannelsInitializer channelsInitializer) {
         super(context);
         assert BuildInfo.isAtLeastO();
-        NotificationManager notificationManager =
-                (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
-        /*
-        The code in the try-block uses reflection in order to compile as it calls APIs newer than
-        our target version of Android. The equivalent code without reflection is as follows:
-
-            notificationManager.createNotificationChannelGroup(
-                    new NotificationChannelGroup(channelGroupId, channelGroupName));
-            NotificationChannel channel = new NotificationChannel(
-                    channelId, channelName, importance);
-            channel.setGroup(channelGroupId);
-            channel.setShowBadge(false);
-            notificationManager.createNotificationChannel(channel);
-            notificationBuilder.setChannel(channelId);
-
-        Note this whole class can be removed once we target O, and channels may be set
-        inline where notifications are created, using the pattern above.
-
-        In the longer term we may wish to initialize our channels in response to BOOT_COMPLETED or
-        ACTION_PACKAGE_REPLACED, as per Android guidelines.
-         */
+        channelsInitializer.ensureInitialized(channelId);
+        // TODO(crbug.com/707804) Stop using reflection once compileSdkVersion is high enough.
         try {
-            // Create channel group
-            Class<?> channelGroupClass = Class.forName("android.app.NotificationChannelGroup");
-            Constructor<?> channelGroupConstructor =
-                    channelGroupClass.getDeclaredConstructor(String.class, CharSequence.class);
-            Object channelGroup =
-                    channelGroupConstructor.newInstance(channelGroupId, channelGroupName);
-
-            // Register channel group
-            Method createNotificationChannelGroupMethod = notificationManager.getClass().getMethod(
-                    "createNotificationChannelGroup", channelGroupClass);
-            createNotificationChannelGroupMethod.invoke(notificationManager, channelGroup);
-
-            // Create channel
-            Class<?> channelClass = Class.forName("android.app.NotificationChannel");
-            Constructor<?> channelConstructor = channelClass.getDeclaredConstructor(
-                    String.class, CharSequence.class, int.class);
-            Object channel = channelConstructor.newInstance(
-                    channelId, channelName, getChannelImportance(channelId));
-
-            // Set group on channel
-            Method setGroupMethod = channelClass.getMethod("setGroup", String.class);
-            setGroupMethod.invoke(channel, channelGroupId);
-
-            // Set channel to not badge on app icon
-            Method setShowBadgeMethod = channelClass.getMethod("setShowBadge", boolean.class);
-            setShowBadgeMethod.invoke(channel, false);
-
-            // Register channel
-            Method createNotificationChannelMethod = notificationManager.getClass().getMethod(
-                    "createNotificationChannel", channelClass);
-            createNotificationChannelMethod.invoke(notificationManager, channel);
-
-            // Set channel on builder
-            Method setChannelMethod =
-                    Notification.Builder.class.getMethod("setChannel", String.class);
-            setChannelMethod.invoke(mBuilder, channelId);
-        } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException
-                | InstantiationException | InvocationTargetException e) {
-            Log.e(TAG, "Error initializing notification builder:", e);
+            Method setChannel = Notification.Builder.class.getMethod("setChannel", String.class);
+            setChannel.invoke(mBuilder, channelId);
+        } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
+            Log.e(TAG, "Error setting channel on notification builder:", e);
         }
     }
-
-    private static int getChannelImportance(String channelId) {
-        return NotificationConstants.CHANNEL_ID_SITES.equals(channelId)
-                ? NotificationManager.IMPORTANCE_DEFAULT
-                : NotificationManager.IMPORTANCE_LOW;
-    }
 }