[Offline pages] Introduction of MarkAttemptStartedTask with tests

components/offline_pages/background/request_coordinator.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_
 #define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_
 
 #include <memory>
 #include <set>
 
@@ skipping 247 matching lines @@
   // Callback from the request picker when no more requests are in the queue.
   // The parameter is a signal for what (if any) conditions to schedule future
   // processing for.
   void RequestNotPicked(bool non_user_requested_tasks_remaining);
 
   void HandleWatchdogTimeout();
 
   // Cancels an in progress pre-rendering, and updates state appropriately.
   void StopPrerendering(Offliner::RequestStatus stop_status);
 
+  // Marks attempt on the request and sends it to offliner in continuation.
   void SendRequestToOffliner(const SavePageRequest& request);

[Pete Williamson, 2016/10/14 17:02:35]

Should this be another task to both mark started and send to offliner? 
(Apologies if that is part of the design, and you just haven't coded it yet).

[dougarnett, 2016/10/14 20:12:31]

But I don't think this does any other queue/store operations besides MarkStarted
so seems good to just have the queue Task cover the db transaction-ish scope but
not more.

[fgorski, 2016/10/14 20:37:19]

No, because right now we are not planning to serialize everything the request
coordinator is doing, only the database access (through request queue). If as a
result of offlining we are getting into situation where something needs to be
written, will will call request queue from there to schedule a relevant task.
And I think Doug provides similar explanation here.

 
+  // Continuation of |SendRequestToOffliner| after the request is marked as
+  // started.
+  void StartOffliner(int64_t request_id,
+                     const std::string& client_namespace,
+                     std::unique_ptr<UpdateRequestsResult> update_result);
+
   // Called by the offliner when an offlining request is completed. (and by
   // tests).
   void OfflinerDoneCallback(const SavePageRequest& request,
                             Offliner::RequestStatus status);
 
   void TryNextRequest();
 
   // If there is an active request in the list, cancel that request.
   bool CancelActiveRequestIfItMatches(const std::vector<int64_t>& request_ids);
 
@@ skipping 85 matching lines @@
   base::TimeDelta offliner_timeout_;
   // Allows us to pass a weak pointer to callbacks.
   base::WeakPtrFactory<RequestCoordinator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RequestCoordinator);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_