[Android O] Upstreaming notification channels code

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
new file mode 100644
index 0000000000000000000000000000000000000000..724daddaa352e04d6b2e817af02197fdd7e2ba4d
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+++ b/chrome/android/java/src/org/chromium/chrome/browser/notifications/NotificationBuilderForO.java
@@ -0,0 +1,99 @@
+// 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 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;
+
+/**
+ * Builder to be used on Android O until we target O and these APIs are in the support library.
+ */
+@TargetApi(26 /* Build.VERSION_CODES.O */)
+public class NotificationBuilderForO extends NotificationBuilder {
+    private static final String TAG = "NotifBuilderForO";
+
+    public NotificationBuilderForO(Context context, String channelId, String channelName,
+            String channelGroupId, String channelGroupName) {
+        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.
+         */
+        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);
+        }
+    }
+
+    private static int getChannelImportance(String channelId) {
+        return NotificationConstants.CATEGORY_ID_SITES.equals(channelId)
+                ? NotificationManager.IMPORTANCE_DEFAULT
+                : NotificationManager.IMPORTANCE_LOW;
+    }
+}