Ensure all content_browsertests call the host resolver in SetUpOnMainThread and not after.

content/test/browser_test_utils_browsertest.cc

 // Copyright 2014 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 "base/macros.h"
 #include "content/public/browser/navigation_handle.h"
 #include "content/public/browser/resource_request_details.h"
 #include "content/public/test/browser_test_utils.h"
 #include "content/public/test/content_browser_test.h"
 #include "content/public/test/content_browser_test_utils.h"
@@ skipping 29 matching lines @@
  private:
   GURL redirect_url_;
   GURL navigation_url_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationObserver);
 };
 
 class CrossSiteRedirectorBrowserTest : public ContentBrowserTest {
  public:
   CrossSiteRedirectorBrowserTest() {}
+
+  void SetUpOnMainThread() override {
+    // Map all hosts to localhost and setup the EmbeddedTestServer for
+    // redirects.
+    host_resolver()->AddRule("*", "127.0.0.1");
+  }
 };
 
 IN_PROC_BROWSER_TEST_F(CrossSiteRedirectorBrowserTest,
                        VerifyCrossSiteRedirectURL) {
-  // Map all hosts to localhost and setup the EmbeddedTestServer for redirects.
-  host_resolver()->AddRule("*", "127.0.0.1");
   SetupCrossSiteRedirector(embedded_test_server());
   ASSERT_TRUE(embedded_test_server()->Start());
 
   // Navigate to http://localhost:<port>/cross-site/foo.com/title2.html and
   // ensure that the redirector forwards the navigation to
   // http://foo.com:<port>/title2.html
   NavigationObserver observer(shell()->web_contents());
   NavigateToURL(
       shell(),
       embedded_test_server()->GetURL("/cross-site/foo.com/title2.html"));
 
   // The expectation is that the cross-site redirector will take the
   // hostname supplied in the URL and rewrite the URL. Build the
   // expected URL to ensure navigation was properly redirected.
   GURL::Replacements replace_host;
   GURL expected_url(embedded_test_server()->GetURL("/title2.html"));
   replace_host.SetHostStr("foo.com");
   expected_url = expected_url.ReplaceComponents(replace_host);
 
   EXPECT_EQ(expected_url, observer.navigation_url());
   EXPECT_EQ(observer.redirect_url(), observer.navigation_url());
 }
 
 }  // namespace content