headless: Remove old load observer API

headless/lib/headless_browser_browsertest.cc

 // Copyright 2016 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 <memory>
 
+#include "base/strings/stringprintf.h"
 #include "content/public/test/browser_test.h"
 #include "headless/public/headless_browser.h"
 #include "headless/public/headless_web_contents.h"
 #include "headless/test/headless_browser_test.h"
 #include "net/test/spawned_test_server/spawned_test_server.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace headless {
 
@@ skipping 57 matching lines @@
   EXPECT_TRUE(WaitForLoad(web_contents));
   EXPECT_EQ(static_cast<size_t>(1), browser()->GetAllWebContents().size());
   EXPECT_EQ(web_contents, browser()->GetAllWebContents()[0]);
   web_contents->Close();
   EXPECT_TRUE(browser()->GetAllWebContents().empty());
 }
 
 IN_PROC_BROWSER_TEST_F(HeadlessBrowserTest, SetHostResolverRules) {
   EXPECT_TRUE(embedded_test_server()->Start());
   HeadlessBrowser::Options::Builder builder;
-  builder.SetHostResolverRules("MAP not-an-actual-domain.tld 127.0.0.1");
+  builder.SetHostResolverRules(
+      base::StringPrintf("MAP not-an-actual-domain.tld 127.0.0.1:%d",
+                         embedded_test_server()->host_port_pair().port()));
   SetBrowserOptions(builder.Build());
 
   // Load a page which doesn't actually exist, but which is turned into a valid
   // address by our host resolver rules.
   HeadlessWebContents* web_contents = browser()->CreateWebContents(
       GURL("http://not-an-actual-domain.tld/hello.html"), gfx::Size(800, 600));
   EXPECT_TRUE(WaitForLoad(web_contents));
 }
 
 }  // namespace headless