[WebAPK] Don't set channel ID of a notification via reflection.

In this CL, we use Notification.Builder.recoverBuilder() to create a Builder
from the notification sent by Chrome, and reset the notification's channel
ID when necessary.

Bug: 700228
Change-Id: I34cfa00ee2cb93935053020da487242709fbb36e
Reviewed-on: https://chromium-review.googlesource.com/810984
Commit-Queue: Xi Han <hanxi@chromium.org>
Reviewed-by: Anita Woodruff <awdf@chromium.org>
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522196}

chrome/android/webapk/shell_apk/shell_apk_version.gni

@@ -6,7 +6,7 @@
 # (including AndroidManifest.xml) is updated. This version should be incremented
 # prior to uploading a new ShellAPK to the WebAPK Minting Server.
 # Does not affect Chrome.apk
-template_shell_apk_version = 36
+template_shell_apk_version = 37
 
 # The ShellAPK version expected by Chrome. Chrome will try to update the WebAPK
 # if the WebAPK's ShellAPK version is less than |expected_shell_apk_version|.

chrome/android/webapk/shell_apk/src/org/chromium/webapk/shell_apk/WebApkServiceImplWrapper.java

@@ -4,11 +4,13 @@
 
 package org.chromium.webapk.shell_apk;
 
+import android.annotation.TargetApi;
 import android.app.Notification;
 import android.app.NotificationChannel;
 import android.app.NotificationManager;
 import android.content.Context;
 import android.os.Binder;
+import android.os.Build;
 import android.os.IBinder;
 import android.os.Parcel;
 import android.os.RemoteException;
@@ -80,10 +82,12 @@ public class WebApkServiceImplWrapper extends IWebApkApi.Stub {
     @Override
     @SuppressWarnings("NewApi")
     public void notifyNotification(String platformTag, int platformID, Notification notification) {
-        // We always rewrite the notification channel id to the WebAPK's default channel id on O+.
+        // The WebApkServiceImplWrapper was introduced at the same time when WebAPKs target SDK 26.
+        // That means, we don't need to check whether the target SDK is less than 26 in a WebAPK
+        // that has a WebApkServiceImplWrapper class.
         if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
             ensureNotificationChannelExists();
-            if (!setNotificationChannelId(notification)) return;
+            notification = rebuildNotificationWithChannelId(mContext, notification);
         }
         delegateNotifyNotification(platformTag, platformID, notification);
     }
@@ -144,22 +148,13 @@ public class WebApkServiceImplWrapper extends IWebApkApi.Stub {
         return false;
     }
 
-    /** Sets the notification channel of the given notification object via reflection. */
-    private boolean setNotificationChannelId(Notification notification) {
-        try {
-            // Now that WebAPKs target SDK 26, we need to set a channel id to display the
-            // notification properly on O+. We set the channel id via reflection because the
-            // notification is already built (and therefore supposedly immutable) when received from
-            // Chrome. This is unavoidable because Notification.Builder is not parcelable.
-            Field channelId = notification.getClass().getDeclaredField("mChannelId");
-            channelId.setAccessible(true);
-            channelId.set(notification, DEFAULT_NOTIFICATION_CHANNEL_ID);
-            return true;
-        } catch (Exception e) {
-            e.printStackTrace();
-        }
-
-        return false;
+    /** Rebuilds a notification with channel ID from the given notification object. */
+    @TargetApi(Build.VERSION_CODES.O)
+    private static Notification rebuildNotificationWithChannelId(
+            Context context, Notification notification) {
+        Notification.Builder builder = Notification.Builder.recoverBuilder(context, notification);
+        builder.setChannelId(DEFAULT_NOTIFICATION_CHANNEL_ID);
+        return builder.build();
     }
 
     /** Calls the delegate's {@link notifyNotification} method via reflection. */