Fix URLLoaderClientImpl to correctly handle deferring

URLLoaderClientImpl should check for both is_deferred flag and for any
pending messages in the DeferredMessage queue (NeedsStoringMessages)
when handling messages. We already use NeedsStoringMessages check when
handling certain messages. This cl also adds this check for the remaining
types: ResponseBody and TransferSizeUpdates.

Change-Id: Iac710721f23a7bd60340956b03dcbeae8eee338d
Reviewed-on: https://chromium-review.googlesource.com/1207251Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589130}

content/renderer/loader/url_loader_client_impl.cc

@@ -285,7 +285,7 @@ void URLLoaderClientImpl::OnReceiveCachedMetadata(
 }
 
 void URLLoaderClientImpl::OnTransferSizeUpdated(int32_t transfer_size_diff) {
-  if (is_deferred_) {
+  if (NeedsStoringMessage()) {
     accumulated_transfer_size_diff_during_deferred_ += transfer_size_diff;
   } else {
     resource_dispatcher_->OnTransferSizeUpdated(request_id_,
@@ -307,7 +307,7 @@ void URLLoaderClientImpl::OnStartLoadingResponseBody(
   body_consumer_ = new URLResponseBodyConsumer(
       request_id_, resource_dispatcher_, std::move(body), task_runner_);
 
-  if (is_deferred_) {
+  if (NeedsStoringMessage()) {
     body_consumer_->SetDefersLoading();
     return;
   }