Fix SitePerProcessBrowserTest.ProcessTransferAfterError to not requiring modifying the mock HostRes…

content/browser/loader/navigation_url_loader_network_service.h

Index: content/browser/loader/navigation_url_loader_network_service.h
diff --git a/content/browser/loader/navigation_url_loader_network_service.h b/content/browser/loader/navigation_url_loader_network_service.h
index 8223c83a19c38b904289d94383e03bd10ec8fb3b..f284a5723361b8680a69419f4cf2af2395122e2f 100644
--- a/content/browser/loader/navigation_url_loader_network_service.h
+++ b/content/browser/loader/navigation_url_loader_network_service.h
@@ -8,6 +8,7 @@
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "content/browser/loader/navigation_url_loader.h"
+#include "content/common/content_export.h"
 #include "content/common/url_loader.mojom.h"
 #include "content/common/url_loader_factory.mojom.h"
 #include "content/public/browser/ssl_status.h"
@@ -39,6 +40,10 @@ class NavigationURLLoaderNetworkService : public NavigationURLLoader,
       NavigationURLLoaderDelegate* delegate);
   ~NavigationURLLoaderNetworkService() override;
 
+  // Overrides the URLLoaderFactory for the next request.
+  static CONTENT_EXPORT void OverrideURLLoaderFactoryForTesting(
+      mojom::URLLoaderFactoryPtr url_loader_factory);
+
   // NavigationURLLoader implementation:
   void FollowRedirect() override;
   void ProceedWithResponse() override;