Fix the Download Notifications for Offline Pages to indicate bytes loaded.

components/offline_pages/core/background/request_coordinator.cc

Index: components/offline_pages/core/background/request_coordinator.cc
diff --git a/components/offline_pages/core/background/request_coordinator.cc b/components/offline_pages/core/background/request_coordinator.cc
index f729bc51c35847bd78afb582e0817cc89fbc4f80..cc80a3424d2d6ade6e83c8a159104717fdc12ca0 100644
--- a/components/offline_pages/core/background/request_coordinator.cc
+++ b/components/offline_pages/core/background/request_coordinator.cc
@@ -883,6 +883,8 @@ void RequestCoordinator::StartOffliner(
   if (offliner_->LoadAndSave(
           update_result->updated_items.at(0),
           base::Bind(&RequestCoordinator::OfflinerDoneCallback,
+                     weak_ptr_factory_.GetWeakPtr()),
+          base::Bind(&RequestCoordinator::OfflinerProgressCallback,
                      weak_ptr_factory_.GetWeakPtr()))) {
     base::TimeDelta timeout;
     if (processing_state_ == ProcessingWindowState::SCHEDULED_WINDOW) {
@@ -934,6 +936,14 @@ void RequestCoordinator::OfflinerDoneCallback(const SavePageRequest& request,
     scheduler_callback_.Run(true);
 }
 
+void RequestCoordinator::OfflinerProgressCallback(
+    const SavePageRequest& request,
+    int64_t received_bytes) {
+  DVLOG(2) << "offliner progress, received bytes: " << received_bytes;
+  DCHECK(received_bytes >= 0);
+  NotifyNetworkProgress(request, received_bytes);
+}
+
 void RequestCoordinator::UpdateRequestForCompletedAttempt(
     const SavePageRequest& request,
     Offliner::RequestStatus status) {
@@ -1066,6 +1076,12 @@ void RequestCoordinator::NotifyChanged(const SavePageRequest& request) {
     observer.OnChanged(request);
 }
 
+void RequestCoordinator::NotifyNetworkProgress(const SavePageRequest& request,
+                                               int64_t received_bytes) {
+  for (Observer& observer : observers_)
+    observer.OnNetworkProgress(request, received_bytes);
+}
+
 ClientPolicyController* RequestCoordinator::GetPolicyController() {
   return policy_controller_.get();
 }