Fix botguard crosstool test failure

Bug:
In url_request_context.cc, we reset proxy_resolution_service_. However,
in http_network_session, we store the original proxy_resolution_service_.
From url_request_context.cc, if we delete the orignal proxy_resolution_service
and create a new object, http_network_session may still try to access
the orignal object. This will trigger the heap-use-after-free error.

b/346555722

cobalt/network/url_request_context.cc

@@ -317,11 +317,17 @@ std::unique_ptr<net::URLRequest> URLRequestContext::CreateRequest(
 void URLRequestContext::SetProxy(const std::string& proxy_rules) {
   net::ProxyConfig proxy_config = CreateCustomProxyConfig(proxy_rules);
   // ProxyService takes ownership of the ProxyConfigService.
-  url_request_context_->set_proxy_resolution_service(
-      net::ConfiguredProxyResolutionService::CreateUsingSystemProxyResolver(
-          std::make_unique<ProxyConfigService>(proxy_config),
-          net::NetLog::Get(),
-          /*quick_check_enabled=*/true));
+  auto proxy_config_service =
+      std::make_unique<ProxyConfigService>(proxy_config);
+  net::ConfiguredProxyResolutionService* proxy_configured_resolution_service =
+      nullptr;
+  bool success = url_request_context_->proxy_resolution_service()
+                     ->CastToConfiguredProxyResolutionService(
+                         &proxy_configured_resolution_service);
+  if (success) {
+    proxy_configured_resolution_service->ResetConfigService(
+        std::move(proxy_config_service));
+  }
 }
 
 void URLRequestContext::SetEnableQuic(bool enable_quic) {

net/proxy_resolution/configured_proxy_resolution_service.cc

@@ -791,6 +791,25 @@ ConfiguredProxyResolutionService::ConfiguredProxyResolutionService(
   config_service_->AddObserver(this);
 }
 
+#if defined(STARBOARD)
+void ConfiguredProxyResolutionService::ResetConfigService(
+    std::unique_ptr<ProxyConfigService> new_proxy_config_service) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  State previous_state = ResetProxyConfig(true);
+
+  // Release the old configuration service.
+  if (config_service_.get())
+    config_service_->RemoveObserver(this);
+
+  // Set the new configuration service.
+  config_service_.reset(new_proxy_config_service.release());
+  config_service_->AddObserver(this);
+
+  if (previous_state != STATE_NONE)
+    ApplyProxyConfigIfAvailable();
+}
+#endif
+
 // static
 std::unique_ptr<ConfiguredProxyResolutionService>
 ConfiguredProxyResolutionService::CreateUsingSystemProxyResolver(

net/proxy_resolution/configured_proxy_resolution_service.h

@@ -177,6 +177,11 @@ class NET_EXPORT ConfiguredProxyResolutionService
   // ProxyResolutionService
   base::Value::Dict GetProxyNetLogValues() override;
 
+#if defined(STARBOARD)
+  void ResetConfigService(
+      std::unique_ptr<ProxyConfigService> new_proxy_config_service);
+#endif
+
   // ProxyResolutionService
   [[nodiscard]] bool CastToConfiguredProxyResolutionService(
       ConfiguredProxyResolutionService** configured_proxy_resolution_service)

net/url_request/url_request_context.h

@@ -134,10 +134,6 @@ class NET_EXPORT URLRequestContext final {
   ProxyResolutionService* proxy_resolution_service() const {
     return proxy_resolution_service_.get();
   }
-#if defined(STARBOARD)
-  void set_proxy_resolution_service(
-      std::unique_ptr<ProxyResolutionService> proxy_resolution_service);
-#endif
 
   ProxyDelegate* proxy_delegate() const { return proxy_delegate_.get(); }
 
@@ -261,10 +257,8 @@ class NET_EXPORT URLRequestContext final {
   void set_net_log(NetLog* net_log);
   void set_host_resolver(std::unique_ptr<HostResolver> host_resolver);
   void set_cert_verifier(std::unique_ptr<CertVerifier> cert_verifier);
-#if !defined(STARBOARD)
   void set_proxy_resolution_service(
       std::unique_ptr<ProxyResolutionService> proxy_resolution_service);
-#endif
   void set_proxy_delegate(std::unique_ptr<ProxyDelegate> proxy_delegate);
   void set_ssl_config_service(std::unique_ptr<SSLConfigService> service);
   void set_http_auth_handler_factory(