network service: pass PlzNavigate resulting data via mojo data pipe

content/child/web_url_loader_impl.cc

Index: content/child/web_url_loader_impl.cc
diff --git a/content/child/web_url_loader_impl.cc b/content/child/web_url_loader_impl.cc
index 3b31280df50f09dca65106223818b3b9d3ec91b1..944693b41d45609e917985ebf65163a13e9fe78c 100644
--- a/content/child/web_url_loader_impl.cc
+++ b/content/child/web_url_loader_impl.cc
@@ -602,11 +602,16 @@ void WebURLLoaderImpl::Context::Start(const WebURLRequest& request,
   // PlzNavigate: during navigation, the renderer should request a stream which
   // contains the body of the response. The network request has already been
   // made by the browser.
+  mojo::ScopedDataPipeConsumerHandle consumer_handle;
   if (stream_override_.get()) {
     CHECK(IsBrowserSideNavigationEnabled());
     DCHECK(!sync_load_response);
     DCHECK_NE(WebURLRequest::kFrameTypeNone, request.GetFrameType());
-    resource_request->resource_body_stream_url = stream_override_->stream_url;
+    if (stream_override_->consumer_handle.is_valid()) {
+      consumer_handle = std::move(stream_override_->consumer_handle);
+    } else {
+      resource_request->resource_body_stream_url = stream_override_->stream_url;
+    }
   }
 
   // PlzNavigate: Invalid renderer main resource requests are rejected by the
@@ -641,7 +646,8 @@ void WebURLLoaderImpl::Context::Start(const WebURLRequest& request,
       std::move(resource_request), request.RequestorID(), task_runner_,
       extra_data->frame_origin(),
       base::MakeUnique<WebURLLoaderImpl::RequestPeerImpl>(this),
-      request.GetLoadingIPCType(), url_loader_factory_);
+      request.GetLoadingIPCType(), url_loader_factory_,
+      std::move(consumer_handle));
 
   if (defers_loading_ != NOT_DEFERRING)
     resource_dispatcher_->SetDefersLoading(request_id_, true);
@@ -808,6 +814,9 @@ void WebURLLoaderImpl::Context::OnReceivedData(
   if (!client_)
     return;
 
+  if (stream_override_.get())
+    stream_override_->total_transferred += data_length;

[jam, 2017/04/12 18:13:45]

I don't understand this block and the one below. Mainly, why isn't this needed
previously with just the mojo URL loading, and why we need it when we turn on
data pipe?

[scottmg, 2017/04/12 18:42:41]

I didn't understand why this was needed either. I'll debug a bit to figure out
what's going on here.

[jam, 2017/04/12 20:36:32]

(per chat) please add this comment, or something like it, cause this was not
intuitive :)

Since ResourceDispatcher::ContinueForNavigation called OnComplete immediately,
it didn't have the size of the resource immediately. So as data is read off the
data pipe, keep track of how much we're reading.




Also, to avoid changing behavior for non-network-service path, only do this
block and below when stream_url.is_empty() (i.e. using the data pipe).

+
   TRACE_EVENT_WITH_FLOW0(
       "loading", "WebURLLoaderImpl::Context::OnReceivedData",
       this, TRACE_EVENT_FLAG_FLOW_IN | TRACE_EVENT_FLAG_FLOW_OUT);
@@ -850,6 +859,12 @@ void WebURLLoaderImpl::Context::OnCompletedRequest(
     const base::TimeTicks& completion_time,
     int64_t total_transfer_size,
     int64_t encoded_body_size) {
+  if (stream_override_.get()) {
+    // XXX This is wrong.
+    total_transfer_size = stream_override_->total_transferred;
+    encoded_body_size = stream_override_->total_transferred;
+  }
+
   if (ftp_listing_delegate_) {
     ftp_listing_delegate_->OnCompletedRequest();
     ftp_listing_delegate_.reset(NULL);