[Android O] Refactor channel definitions into new class

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadNotificationService.java

Index: chrome/android/java/src/org/chromium/chrome/browser/download/DownloadNotificationService.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadNotificationService.java b/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadNotificationService.java
index 11100df5566dfe242e4a0806984ce3a5b7a7fdf3..1b367f6651c8c806616a446c31aaad099d94b8be 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadNotificationService.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadNotificationService.java
@@ -46,7 +46,7 @@ import org.chromium.chrome.browser.download.items.OfflineContentAggregatorNotifi
 import org.chromium.chrome.browser.init.BrowserParts;
 import org.chromium.chrome.browser.init.ChromeBrowserInitializer;
 import org.chromium.chrome.browser.init.EmptyBrowserParts;
-import org.chromium.chrome.browser.notifications.ChannelsInitializer;
+import org.chromium.chrome.browser.notifications.ChannelDefinitions;
 import org.chromium.chrome.browser.notifications.ChromeNotificationBuilder;
 import org.chromium.chrome.browser.notifications.NotificationBuilderFactory;
 import org.chromium.chrome.browser.notifications.NotificationConstants;
@@ -363,7 +363,7 @@ public class DownloadNotificationService extends Service {
         ChromeNotificationBuilder builder =
                 NotificationBuilderFactory
                         .createChromeNotificationBuilder(
-                                true /* preferCompat */, ChannelsInitializer.CHANNEL_ID_DOWNLOADS)
+                                true /* preferCompat */, ChannelDefinitions.CHANNEL_ID_DOWNLOADS)
                         .setContentTitle(
                                 context.getString(R.string.download_notification_summary_title))
                         .setSubText(context.getString(R.string.menu_downloads))
@@ -1090,7 +1090,7 @@ public class DownloadNotificationService extends Service {
         ChromeNotificationBuilder builder =
                 NotificationBuilderFactory
                         .createChromeNotificationBuilder(
-                                true /* preferCompat */, ChannelsInitializer.CHANNEL_ID_DOWNLOADS)
+                                true /* preferCompat */, ChannelDefinitions.CHANNEL_ID_DOWNLOADS)
                         .setContentTitle(
                                 DownloadUtils.getAbbreviatedFileName(title, MAX_FILE_NAME_LENGTH))
                         .setSmallIcon(iconId)