Introduce SystemNetworkContextManager.

chrome/browser/net/system_network_context_manager.cc

+// 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.
+
+#include "chrome/browser/net/system_network_context_manager.h"
+
+#include "base/feature_list.h"
+#include "base/logging.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/network_service_instance.h"
+#include "content/public/common/content_features.h"
+#include "content/public/common/service_names.mojom.h"
+#include "mojo/public/cpp/bindings/associated_interface_ptr.h"
+
+namespace {
+
+content::mojom::NetworkContextParamsPtr CreateNetworkContextParams() {
+  // TODO(mmenke): Set up parameters here (No cache, in memory cookie store,
+  // etc).
+  return content::mojom::NetworkContextParams::New();
+}
+
+}  // namespace
+
+base::LazyInstance<SystemNetworkContextManager>::Leaky
+    g_system_network_context_manager = LAZY_INSTANCE_INITIALIZER;
+
+content::mojom::NetworkContext* SystemNetworkContextManager::Context() {
+  return GetInstance()->GetContext();
+}
+
+void SystemNetworkContextManager::SetUp(
+    content::mojom::NetworkContextRequest* network_context_request,
+    content::mojom::NetworkContextParamsPtr* network_context_params) {
+  DCHECK(!GetInstance()->io_thread_network_context_);
+  *network_context_request =
+      mojo::MakeRequest(&GetInstance()->io_thread_network_context_);
+  *network_context_params = CreateNetworkContextParams();
+}
+
+SystemNetworkContextManager* SystemNetworkContextManager::GetInstance() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  return g_system_network_context_manager.Pointer();
+}
+
+SystemNetworkContextManager::SystemNetworkContextManager() {}
+
+SystemNetworkContextManager::~SystemNetworkContextManager() {}
+
+content::mojom::NetworkContext* SystemNetworkContextManager::GetContext() {
+  if (!base::FeatureList::IsEnabled(features::kNetworkService)) {
+    // SetUp should already have been called.
+    DCHECK(io_thread_network_context_);
+    return io_thread_network_context_.get();
+  }
+
+  if (!network_service_network_context_) {
+    content::GetNetworkService()->CreateNetworkContext(
+        MakeRequest(&network_service_network_context_),
+        CreateNetworkContextParams());
+  }
+  return network_service_network_context_.get();
+}