Increase limitless prefetch start delay to 20s, up from 5s.

Testing Offline Prefetch in reduced mode manually requires a bit more
time.

Bug: 933358
Change-Id: Iea9e52fda62bbf7fc2251fe3ca8eef2d110f4889
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1626495
Commit-Queue: Carlos Knippschild <carlosk@chromium.org>
Auto-Submit: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Carlos Knippschild <carlosk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666471}

chrome/android/java/src/org/chromium/chrome/browser/offlinepages/prefetch/PrefetchBackgroundTaskScheduler.java

@@ -20,7 +20,7 @@ import org.chromium.components.background_task_scheduler.TaskInfo;
 @JNINamespace("offline_pages::prefetch")
 public class PrefetchBackgroundTaskScheduler {
     public static final long DEFAULT_START_DELAY_SECONDS = 15 * 60;
-    public static final long LIMITLESS_START_DELAY_SECONDS = 5;
+    public static final long LIMITLESS_START_DELAY_SECONDS = 20;
 
     /**
      * Schedules the default 'NWake' task for the prefetching service. This task will normally be