feat: migrate protocol module to NetworkService (Part 4) (#18084)

* Parse stream protocol handler

* Pipe node stream to mojo

* Merge the parser for headers

* Add ToDict helper to simplify code

* Simplify dispatching logic

* Add an experimental API for returning any type of response

* Fix subscribing event

* URL loaders' lifetime is independent of the factory

* HandleError helper is no longer needed

* Rename "SendResponse" => "StartLoading" to follow naming conventions

* Delete when connection error happens

* Fix cpplint warning

atom/browser/net/node_stream_loader.h

@@ -0,0 +1,77 @@
+// Copyright (c) 2019 GitHub, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#ifndef ATOM_BROWSER_NET_NODE_STREAM_LOADER_H_
+#define ATOM_BROWSER_NET_NODE_STREAM_LOADER_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "services/network/public/mojom/url_loader.mojom.h"
+#include "v8/include/v8.h"
+
+namespace mate {
+class Arguments;
+}
+
+namespace atom {
+
+class NodeStreamLoader : public network::mojom::URLLoader {
+ public:
+  NodeStreamLoader(network::ResourceResponseHead head,
+                   network::mojom::URLLoaderRequest loader,
+                   network::mojom::URLLoaderClientPtr client,
+                   v8::Isolate* isolate,
+                   v8::Local<v8::Object> emitter);
+
+ private:
+  ~NodeStreamLoader() override;
+
+  using EventCallback = base::RepeatingCallback<void(mate::Arguments* args)>;
+
+  // URLLoader:
+  void FollowRedirect(const std::vector<std::string>& removed_headers,
+                      const net::HttpRequestHeaders& modified_headers,
+                      const base::Optional<GURL>& new_url) override {}
+  void ProceedWithResponse() override {}
+  void SetPriority(net::RequestPriority priority,
+                   int32_t intra_priority_value) override {}
+  void PauseReadingBodyFromNet() override {}
+  void ResumeReadingBodyFromNet() override {}
+
+  // JS bindings.
+  void On(const char* event, EventCallback callback);
+  void OnData(mate::Arguments* args);
+  void OnEnd(mate::Arguments* args);
+  void OnError(mate::Arguments* args);
+
+  // This class manages its own lifetime and should delete itself when the
+  // connection is lost or finished.
+  //
+  // The code is updated with `content::FileURLLoader`.
+  void OnConnectionError();
+  void MaybeDeleteSelf();
+
+  mojo::Binding<network::mojom::URLLoader> binding_;
+  network::mojom::URLLoaderClientPtr client_;
+
+  v8::Isolate* isolate_;
+  v8::Global<v8::Object> emitter_;
+
+  // Pipes for communicating between Node and NetworkService.
+  mojo::ScopedDataPipeProducerHandle producer_;
+
+  // Store the V8 callbacks to unsubscribe them later.
+  std::map<std::string, v8::Global<v8::Value>> handlers_;
+
+  base::WeakPtrFactory<NodeStreamLoader> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(NodeStreamLoader);
+};
+
+}  // namespace atom
+
+#endif  // ATOM_BROWSER_NET_NODE_STREAM_LOADER_H_