Add an error page for HTTP 404 error pages without bodies.

chrome/browser/extensions/api/web_navigation/web_navigation_apitest.cc

 // Copyright (c) 2012 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 <list>
 #include <set>
 
 #include "base/files/scoped_temp_dir.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
@@ skipping 312 matching lines @@
     if (throttle)
       throttles->push_back(throttle);
   }
 
  private:
   scoped_refptr<TestNavigationListener> test_navigation_listener_;
 
   DISALLOW_COPY_AND_ASSIGN(TestResourceDispatcherHostDelegate);
 };
 
+// Handles requests for URLs with paths of "/test*" sent to the test server, so
+// tests request a URL that receives a non-error response.
+std::unqiue_ptr<net::test_server::HttpResponse> HandleTestRequest(
+    const net::test_server::HttpRequest& request) {
+  if (!base::StartsWithASCII(request.relative_url, "/test"))
+    return nullptr;
+  std::unique_ptr<net::test_server::BasicHttpResponse> response(
+      new net::test_server::BasicHttpResponse());
+  response->set_content("This space intentionally left blank.");
+  return std::move(response);
+}
+
 }  // namespace
 
 class WebNavigationApiTest : public ExtensionApiTest {
  public:
-  WebNavigationApiTest() {}
+  WebNavigationApiTest() {
+    embedded_test_server()->RegisterRequestHandler(
+        base::Bind(&HandleTestRequest));
+  }
   ~WebNavigationApiTest() override {}
 
   void SetUpInProcessBrowserTestFixture() override {
     ExtensionApiTest::SetUpInProcessBrowserTestFixture();
 
     FrameNavigationState::set_allow_extension_scheme(true);
 
     base::CommandLine::ForCurrentProcess()->AppendSwitch(
         switches::kAllowLegacyExtensionManifests);
 
@@ skipping 424 matching lines @@
           "extensions/api_test/webnavigation/crash/b.html",
       embedded_test_server()->port()));
   ui_test_utils::NavigateToURL(browser(), url);
 
   ASSERT_TRUE(catcher.GetNextResult()) << catcher.message();
 }
 
 #endif
 
 }  // namespace extensions