[Offline pages]: Implement background loader to save on last retry, and record last retry success U…

chrome/browser/android/offline_pages/prerendering_offliner.cc

Index: chrome/browser/android/offline_pages/prerendering_offliner.cc
diff --git a/chrome/browser/android/offline_pages/prerendering_offliner.cc b/chrome/browser/android/offline_pages/prerendering_offliner.cc
index db341ef4c87b63951480215df3ff2f69ab5334b3..78886327ae233f284f7cd61227ba8914f728286c 100644
--- a/chrome/browser/android/offline_pages/prerendering_offliner.cc
+++ b/chrome/browser/android/offline_pages/prerendering_offliner.cc
@@ -38,6 +38,7 @@ PrerenderingOffliner::PrerenderingOffliner(
       offline_page_model_(offline_page_model),
       pending_request_(nullptr),
       is_low_end_device_(base::SysInfo::IsLowEndDevice()),
+      saved_on_last_retry_(false),
       app_listener_(nullptr),
       weak_ptr_factory_(this) {}
 
@@ -158,12 +159,16 @@ void PrerenderingOffliner::OnSavePageDone(
   // Determine status and run the completion callback.
   Offliner::RequestStatus save_status;
   if (save_result == SavePageResult::SUCCESS) {
-    save_status = RequestStatus::SAVED;
+    if (saved_on_last_retry_)
+      save_status = RequestStatus::SAVED_ON_LAST_RETRY;
+    else
+      save_status = RequestStatus::SAVED;
   } else {
     // TODO(dougarnett): Consider reflecting some recommendation to retry the
     // request based on specific save error cases.
     save_status = RequestStatus::SAVE_FAILED;
   }
+  saved_on_last_retry_ = false;

[fgorski, 2017/04/17 17:48:59]

Would a single prerendering offliner be used for multiple snapshots? If so is
this covering all cases when this field has to be reset to false?

Otherwise, in case it does not take multiple snapshots, why bother resetting the
value?

[chili, 2017/04/17 19:37:52]

Good point. Added an additional clearing when we first LoadAndSave a page. The
PrerenderingOffliner is used across multiple snapshots.

   completion_callback_.Run(request, save_status);
 }
 
@@ -268,6 +273,7 @@ bool PrerenderingOffliner::HandleTimeout(const SavePageRequest& request) {
         (request.started_attempt_count() + 1 >= policy_->GetMaxStartedTries() ||
          request.completed_attempt_count() + 1 >=
              policy_->GetMaxCompletedTries())) {
+      saved_on_last_retry_ = true;
       GetOrCreateLoader()->StartSnapshot();
       return true;
     }