[Offline pages] Introduction of MarkAttemptStartedTask with tests

components/offline_pages/background/request_queue.cc

Index: components/offline_pages/background/request_queue.cc
diff --git a/components/offline_pages/background/request_queue.cc b/components/offline_pages/background/request_queue.cc
index b491824edebd3870ab479ec1973d939f3bb0115e..d3f48d2a9a238de19cbeeb9d37b4fe2e1bace2e1 100644
--- a/components/offline_pages/background/request_queue.cc
+++ b/components/offline_pages/background/request_queue.cc
@@ -8,6 +8,7 @@
 #include "base/location.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/offline_pages/background/change_requests_state_task.h"
+#include "components/offline_pages/background/mark_attempt_started_task.h"
 #include "components/offline_pages/background/remove_requests_task.h"
 #include "components/offline_pages/background/request_queue_store.h"
 #include "components/offline_pages/background/save_page_request.h"
@@ -159,6 +160,13 @@ void RequestQueue::ChangeRequestsState(
   task_queue_.AddTask(std::move(task));
 }
 
+void RequestQueue::MarkAttemptStarted(int64_t request_id,
+                                      const UpdateCallback& callback) {
+  std::unique_ptr<Task> task(
+      new MarkAttemptStartedTask(store_.get(), request_id, callback));
+  task_queue_.AddTask(std::move(task));
+}
+
 void RequestQueue::PurgeRequests(const PurgeRequestsCallback& callback) {}
 
 }  // namespace offline_pages