[Offline Prefetch] Create a new JobScheduler task to wake up for net activity.

chrome/browser/BUILD.gn

Index: chrome/browser/BUILD.gn
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index ae72f49f6e45a0fb751eb180b1fae3d4aaf3655e..3160335915bf5498c6f6d3024931a42d0a71f7c4 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -2897,6 +2897,8 @@ split_static_library("browser") {
       "android/offline_pages/offliner_factory.h",
       "android/offline_pages/offliner_helper.cc",
       "android/offline_pages/offliner_helper.h",
+      "android/offline_pages/prefetch/prefetch_background_task.cc",
+      "android/offline_pages/prefetch/prefetch_background_task.h",
       "android/offline_pages/prerender_adapter.cc",
       "android/offline_pages/prerender_adapter.h",
       "android/offline_pages/prerendering_loader.cc",
@@ -4169,6 +4171,7 @@ if (is_android) {
       "../android/java/src/org/chromium/chrome/browser/offlinepages/SavePageRequest.java",
       "../android/java/src/org/chromium/chrome/browser/offlinepages/downloads/OfflinePageDownloadBridge.java",
       "../android/java/src/org/chromium/chrome/browser/offlinepages/downloads/OfflinePageNotificationBridge.java",
+      "../android/java/src/org/chromium/chrome/browser/offlinepages/prefetch/PrefetchBackgroundTask.java",
       "../android/java/src/org/chromium/chrome/browser/omnibox/AnswersImage.java",
       "../android/java/src/org/chromium/chrome/browser/omnibox/AutocompleteController.java",
       "../android/java/src/org/chromium/chrome/browser/omnibox/OmniboxPrerender.java",