Bring back the URLLoader from the old Mandoline network service.

content/network/network_context.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_NETWORK_NETWORK_CONTEXT_H_
+#define CONTENT_NETWORK_NETWORK_CONTEXT_H_
+
+#include <stdint.h>
+
+#include <memory>
+#include <set>
+
+#include "base/macros.h"
+#include "content/common/content_export.h"
+
+namespace net {
+class URLRequestContext;
+}
+
+namespace content {
+class URLLoaderImpl;
+
+class CONTENT_EXPORT NetworkContext {
+ public:
+  NetworkContext();
+  ~NetworkContext();
+
+  net::URLRequestContext* url_request_context() {
+    return url_request_context_.get();
+  }
+
+  // These are called by individual url loaders as they are being created and
+  // destroyed.
+  void RegisterURLLoader(URLLoaderImpl* url_loader);
+  void DeregisterURLLoader(URLLoaderImpl* url_loader);
+
+ private:
+  class MojoNetLog;
+  std::unique_ptr<MojoNetLog> net_log_;
+
+  std::unique_ptr<net::URLRequestContext> url_request_context_;
+
+  // URLLoaderImpls register themselves with the NetworkContext so that they can
+  // be cleaned up when the NetworkContext goes away. This is needed as
+  // net::URLRequests held by URLLoaderImpls have to be gone when
+  // net::URLRequestContext (held by NetworkContext) is destroyed.
+  std::set<URLLoaderImpl*> url_loaders_;
+
+  // Set when entering the destructor, in order to avoid manipulations of the
+  // |url_loaders_| (as a url_loader might delete itself in Cleanup()).
+  bool in_shutdown_;
+
+  DISALLOW_COPY_AND_ASSIGN(NetworkContext);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_NETWORK_NETWORK_CONTEXT_H_