Test for navigating back to navigation that posts to a cross-site 307 redirect.

content/public/test/browser_test_utils.h

Index: content/public/test/browser_test_utils.h
diff --git a/content/public/test/browser_test_utils.h b/content/public/test/browser_test_utils.h
index 6b2adffa3bf69b7ba6ad4f2e961b0e8ad9277de4..a0f3dd8c9805be461f5ee3dce822a2486a4afe3a 100644
--- a/content/public/test/browser_test_utils.h
+++ b/content/public/test/browser_test_utils.h
@@ -264,6 +264,12 @@ void FetchHistogramsFromChildProcesses();
 // "/cross-site/hostname/rest/of/path" to redirect the request to
 // "<scheme>://hostname:<port>/rest/of/path", where <scheme> and <port>
 // are the values for the instance of EmbeddedTestServer.
+//
+// By default, redirection will be done using HTTP 302 response, but in some
+// cases (e.g. to preserve HTTP method and POST body across redirects as
+// prescribed by https://tools.ietf.org/html/rfc7231#section-6.4.7) a test might
+// want to use HTTP 307 response instead.  This can be accomplished by replacing
+// "/cross-site/" URL substring above with "/cross-site-307/".
 void SetupCrossSiteRedirector(net::EmbeddedTestServer* embedded_test_server);
 
 // Waits for an interstitial page to attach to given web contents.