Introduce SystemNetworkContextManager.

chrome/browser/net/system_network_context_manager.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 CHROME_BROWSER_NET_SYSTEM_NETWORK_CONTEXT_MANAGER_H_
+#define CHROME_BROWSER_NET_SYSTEM_NETWORK_CONTEXT_MANAGER_H_
+
+#include <memory>
+
+#include "base/lazy_instance.h"
+#include "base/macros.h"
+#include "content/public/common/network_service.mojom.h"
+
+// Global object that lives on the UI thread. Responsible for creating and
+// managing access to the system NetworkContext. This NetworkContext is intended
+// for requests not associated with a profile. It stores no data on disk, and
+// has no HTTP cache, but it does have ephemeral cookie and channel ID stores.
+// It also does not have access to HTTP proxy auth information the user has
+// entered or that comes from extensions, and similarly, has no
+// extension-provided per-profile proxy configuration information.
+//
+// The "system" NetworkContext will either share a URLRequestContext with
+// IOThread's SystemURLRequestContext (If the OOP NetworkService is disabled) or

[jam, 2017/07/08 01:30:08]

nit: here and below, I think OOP is not necessary as in my other comments right?
i.e. once we enable network service, even if it's running in-process then the
NetworkService path would be taken

[mmenke, 2017/07/10 15:52:22]

I've removed all instances of OOP (I now refer to it as the network service [No
caps], and in a couple places try to make the distinction between the IOThread's
NetworkService and the actual network service clear.

+// be an independent NetworkContext in the OOP NetworkService.
+//
+// This class is intended to eventually replace IOThread. Handling the two cases
+// differently allows this to be used in production without breaking anything or
+// requiring two separate paths, while IOThread consumers slowly transition over
+// to being compatible with an OOP NetworkService.
+class SystemNetworkContextManager {
+ public:
+  // Initializes |network_context_params| as needed to set up a system
+  // NetworkContext. If the OOP NetworkService is disabled,
+  // |network_context_request| will be for the NetworkContext used by the
+  // SystemNetworkContextManager. Otherwise, this method can still be used to
+  // help set up the IOTHread's in-process URLRequestContext, and
+  // |network_context_request| will still be populated, but the associated
+  // NetworkContext will not be used by the SystemNetworkContextManager.
+  //
+  // Must be called before the system NetworkContext is first used.
+  static void SetUp(
+      content::mojom::NetworkContextRequest* network_context_request,
+      content::mojom::NetworkContextParamsPtr* network_context_params);
+
+  // Returns the System NetworkContext. May only be called after Initialize().

[kinuko, 2017/07/10 08:10:33]

Wasn't sure what this Initialize points to, do you mean SetUp?

[mmenke, 2017/07/10 15:52:22]

Done, thanks (Renamed the method itself once I move initialization into
GetContext() in the network service case)

+  static content::mojom::NetworkContext* Context();
+
+ private:
+  static SystemNetworkContextManager* GetInstance();
+
+  friend struct base::LazyInstanceTraitsBase<SystemNetworkContextManager>;
+
+  SystemNetworkContextManager();
+  ~SystemNetworkContextManager();
+
+  // Gets the system NetworkContext, creating it if needed.
+  content::mojom::NetworkContext* GetContext();
+
+  // The NetworkContext used by the |SystemNetworkContextManager|. If the OOP
+  // NetworkService is enabled, it's a NetworkContext using that NetworkService.
+  // If it's not enabled, it's a NetworkContext wrapping the IOThread's
+  // SystemURLRequestContext.
+  content::mojom::NetworkContextPtr system_network_context_;
+
+  // When the OOP NetworkService is enabled, this is a NetworkContext that wraps
+  // the IOThread's SystemURLRequestContext, and is never used after
+  // initialization. It's nullptr, otherwise.
+  content::mojom::NetworkContextPtr io_thread_network_context_;
+
+  DISALLOW_COPY_AND_ASSIGN(SystemNetworkContextManager);
+};
+
+#endif  // CHROME_BROWSER_NET_SYSTEM_NETWORK_CONTEXT_MANAGER_H_