Split the RequestPicker task into two separate tasks.

components/offline_pages/background/BUILD.gn

Index: components/offline_pages/background/BUILD.gn
diff --git a/components/offline_pages/background/BUILD.gn b/components/offline_pages/background/BUILD.gn
index 06a074f5918d3df7099120827a113818a3d25b18..fd5ab2f096a5f332d84a037c32cfc1236adfd907 100644
--- a/components/offline_pages/background/BUILD.gn
+++ b/components/offline_pages/background/BUILD.gn
@@ -12,6 +12,10 @@ static_library("background_offliner") {
     "add_request_task.h",
     "change_requests_state_task.cc",
     "change_requests_state_task.h",
+    "cleanup_task.cc",
+    "cleanup_task.h",
+    "cleanup_task_factory.cc",
+    "cleanup_task_factory.h",
     "connection_notifier.cc",
     "connection_notifier.h",
     "device_conditions.h",
@@ -28,10 +32,10 @@ static_library("background_offliner") {
     "offliner.h",
     "offliner_factory.h",
     "offliner_policy.h",
+    "offliner_policy_utils.cc",
+    "offliner_policy_utils.h",
     "pick_request_task.cc",
     "pick_request_task.h",
-    "pick_request_task_factory.cc",
-    "pick_request_task_factory.h",
     "remove_requests_task.cc",
     "remove_requests_task.h",
     "request_coordinator.cc",
@@ -91,6 +95,7 @@ source_set("unit_tests") {
   sources = [
     "add_request_task_unittest.cc",
     "change_requests_state_task_unittest.cc",
+    "cleanup_task_unittest.cc",
     "get_requests_task_unittest.cc",
     "initialize_store_task_unittest.cc",
     "mark_attempt_aborted_task_unittest.cc",