PROTOTYPE: PlzNavigate: use a Mojo data pipe to stream navigation data to the renderer.

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 2b9d783dc2f095bfb18439cbf41a802a624a32c9..910f533cde646b973f6685ba434842872c38f20e 100644
--- a/content/child/web_url_loader_impl.cc
+++ b/content/child/web_url_loader_impl.cc
@@ -289,6 +289,10 @@ void SetSecurityStyleAndDetails(const GURL& url,
 
 }  // namespace
 
+StreamOverrideParameters::StreamOverrideParameters() : browser_request_id(-1) {}
+
+StreamOverrideParameters::~StreamOverrideParameters() {}
+
 // This inner class exists since the WebURLLoader may be deleted while inside a
 // call to WebURLLoaderClient.  Refcounting is to keep the context from being
 // deleted if it may have work to do after calling into the client.
@@ -542,25 +546,32 @@ void WebURLLoaderImpl::Context::Start(const WebURLRequest& request,
   scoped_refptr<ResourceRequestBody> request_body =
       GetRequestBodyForWebURLRequest(request).get();
 
-  // 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.
-  if (stream_override_.get()) {
-    CHECK(IsBrowserSideNavigationEnabled());
-    DCHECK(!sync_load_response);
-    DCHECK_NE(WebURLRequest::FrameTypeNone, request.getFrameType());
-    request_info.resource_body_stream_url = stream_override_->stream_url;
-  }
-
   if (sync_load_response) {
+    DCHECK(!stream_override_);
     resource_dispatcher_->StartSync(
         request_info, request_body.get(), sync_load_response);
     return;
   }
 
+  // PlzNavigate: during navigation, the browser should have sent a consumer
+  // handle for a Mojo data pipe along with the respective browser generated
+  // request id. The network request has already been made by the browser.
+  mojo::ScopedDataPipeConsumerHandle mojo_data_pipe_handle;
+  int browser_request_id = -1;
+  if (stream_override_) {
+    CHECK(IsBrowserSideNavigationEnabled());
+    DCHECK(!sync_load_response);
+    DCHECK_NE(WebURLRequest::FrameTypeNone, request.getFrameType());
+    DCHECK(stream_override_->mojo_handle.is_valid());
+    DCHECK_LT(stream_override_->browser_request_id, -1);
+    mojo_data_pipe_handle = std::move(stream_override_->mojo_handle);
+    browser_request_id = stream_override_->browser_request_id;
+  }
+
   request_id_ = resource_dispatcher_->StartAsync(
       request_info, request_body.get(),
-      make_scoped_ptr(new WebURLLoaderImpl::RequestPeerImpl(this)));
+      make_scoped_ptr(new WebURLLoaderImpl::RequestPeerImpl(this)),
+      std::move(mojo_data_pipe_handle), browser_request_id);
 }
 
 void WebURLLoaderImpl::Context::SetWebTaskRunner(