Improve the page download:

components/offline_pages/background/request_coordinator.cc

Index: components/offline_pages/background/request_coordinator.cc
diff --git a/components/offline_pages/background/request_coordinator.cc b/components/offline_pages/background/request_coordinator.cc
index c4d602e0aecdb5a67c671041ef82a39b9c130300..087be6fa282ab13431bbe9e88b9f980e9117a73a 100644
--- a/components/offline_pages/background/request_coordinator.cc
+++ b/components/offline_pages/background/request_coordinator.cc
@@ -638,12 +638,22 @@ void RequestCoordinator::OfflinerDoneCallback(const SavePageRequest& request,
 }
 
 void RequestCoordinator::EnableForOffliner(int64_t request_id) {
-    disabled_requests_.erase(request_id);
-    // If we are not busy, start processing right away.
-    StartProcessingIfConnected();
+  // Since the recent tab helper might call multiple times, ignore subsequent
+  // calls for a particular request_id.
+  if (disabled_requests_.find(request_id) == disabled_requests_.end())
+    return;
+  disabled_requests_.erase(request_id);
+  // If we are not busy, start processing right away.
+  StartProcessingIfConnected();
 }
 
 void RequestCoordinator::MarkRequestCompleted(int64_t request_id) {
+  // Since the recent tab helper might call multiple times, ignore subsequent
+  // calls for a particular request_id.
+  if (disabled_requests_.find(request_id) == disabled_requests_.end())
+    return;
+  disabled_requests_.erase(request_id);
+
   // Remove the request, but send out SUCCEEDED instead of removed.
   std::vector<int64_t> request_ids { request_id };
     queue_->RemoveRequests(