Allow TestURLLoaderFactory::SimulateResponse's mock responses to fail

This CL makes the TestURLLoaderFactory::SimulateResponse API more flexible in the following ways:

- it starts to actually use the |net_error| parameter (to build the URLLoaderCompletionatus
  instance)
- it adds an extra (also optional) net::HttpStatusCode parameter, so that
  one can more easily mock failing responses.
- one can see it in action in [1].

[1] https://crrev.com/c/1114998/components/autofill/core/browser/autofill_download_manager_unittest.cc#283

Bug: 773295
Cq-Include-Trybots: luci.chromium.try:linux_mojo
Change-Id: Iba4edf640b3ff82e035ffbe26c3066d404f18ce7
Reviewed-on: https://chromium-review.googlesource.com/1120916
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Reviewed-by: Antonio Gomes <tonikitoo@igalia.com>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571635}

services/network/test/test_url_loader_factory.cc

@@ -133,9 +133,10 @@ bool TestURLLoaderFactory::CreateLoaderAndStartInternal(
 void TestURLLoaderFactory::SimulateResponse(
     TestURLLoaderFactory::PendingRequest request,
     std::string content,
-    int net_error) {
-  network::URLLoaderCompletionStatus status(net::OK);
-  ResourceResponseHead head = CreateResourceResponseHead(net::HTTP_OK);
+    int net_error,
+    net::HttpStatusCode http_status) {
+  network::URLLoaderCompletionStatus status(net_error);
+  ResourceResponseHead head = CreateResourceResponseHead(http_status);
   status.decoded_body_length = content.size();
   SimulateResponseImpl(request.client.get(), TestURLLoaderFactory::Redirects(),
                        head, content, status);

services/network/test/test_url_loader_factory.h

@@ -78,7 +78,8 @@ class TestURLLoaderFactory : public mojom::URLLoaderFactory {
   // pending_requests(). Prefer using AddResponse.
   static void SimulateResponse(PendingRequest request,
                                std::string content,
-                               int net_error = net::OK);
+                               int net_error = net::OK,
+                               net::HttpStatusCode status = net::HTTP_OK);
 
   static ResourceResponseHead CreateResourceResponseHead(
       net::HttpStatusCode http_status);